Animals Planet

In 1758, the Swedish botanist and zoologistCarl Linnaeuspublished in hisSystema Naturae, the two-word naming of species (binomial nomenclature).Canisis theLatinword meaning "dog",[15]and under thisgenus, he listed the domestic dog, thewolf, and thegolden jackal. He classified the domestic dog asCanis familiarisand, on the next page, classified the grey wolf asCanis lupus.[2]Linnaeus considered the dog to be a separate species from the wolf because of its upturning tail (cauda recurvata), which is not found in any othercanid.[16] In 1999, a study ofmitochondrial DNA(mtDNA) indicated that the domestic dog may have originated from the grey wolf, with thedingoandNew Guinea singing dogbreeds having developed at a time when human communities were more isolated from each other.[17]In the third edition ofMammal Species of the Worldpublished in 2005, themammalogistW. Christopher Wozencraftlisted under the wolfCanis lupusits wild subspecies and proposed two additional subspecies, which formed the domestic dog clade:familiaris, as named by Linnaeus in 1758 and,dingonamed by Meyer in 1793. Wozencraft includedhallstromi(the New Guinea singing dog) as another name (junior synonym) for the dingo. Wozencraft referred to the mtDNA study as one of the guides informing his decision.[3]Mammalogists have noted the inclusion offamiliarisanddingotogether under the "domestic dog" clade[18]with some debating it.[19] In 2019, a workshop hosted by theIUCN/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to beferalCanis familiarisand therefore did not assess them for theIUCN Red List of Threatened Species.[4] Evolution Main article:Evolution of the wolf  Location of a dog'scarnassials; the inside of the 4th upperpremolaraligns with the outside of the 1st lowermolar, working like scissor blades TheCretaceous–Paleogene extinction eventoccurred 65 million years ago and brought an end to the dinosaurs and the appearance of the first carnivorans.[20]The namecarnivoranis given to a member of the orderCarnivora. Carnivorans possess a common arrangement of teeth calledcarnassials, in which the first lowermolarand the last upperpremolarpossess blade-like enamelcrownsthat act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether as in seals, sea lions, and walruses. Today, not all carnivorans arecarnivores, such as the insect-eatingAardwolf.[5] The carnivoran ancestors of the dog-likecaniformsand the cat-likefeliformsbegan their separate evolutionary paths just after the end of the dinosaurs. The first members of the dog familyCanidaeappeared 40 million years ago,[21]of which only its subfamily theCaninaesurvives today in the form of the wolf-like and fox-like canines. Within the Caninae, the first members of genusCanisappeared six million years ago,[15]the ancestors of modern domestic dogs, wolves,coyotes, and golden jackals. Domestication Main article:Domestication of the dog The earliest remains generally accepted to be those of a domesticated dog were discovered inBonn-Oberkassel, Germany. Contextual, isotopic, genetic, and morphological evidence shows that this dog was not a local wolf.[22]The dog was dated to 14,223 years ago and was found buried along with a man and a woman, all three having been sprayed with redhematitepowder and buried under large, thick basalt blocks. The dog had died ofcanine distemper.[23]Earlier remains dating back to 30,000 years ago have been described asPaleolithic dogs, but their status as dogs or wolves remains debated[24]because considerablemorphologicaldiversity existed among wolves during theLate Pleistocene.[1] This timing indicates that the dog was the first species to be domesticated[9][8]in the time ofhunter–gatherers,[7]which predates agriculture.[1]DNA sequencesshow that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from themodern wolflineage.[6][7]Most dogs form a sister group to the remains of a LatePleistocene wolffound in theKessleroch cavenearThayngenin the canton ofSchaffhausen,Switzerland, which dates to 14,500 years ago. Themost recent common ancestorof both is estimated to be from 32,100 years ago.[25]This indicates that an extinct Late Pleistocene wolf may have been the ancestor of the dog,[8][1][26]with the modern wolf being the dog's nearest living relative.[8] The dog is a classic example of a domestic animal that likely travelled acommensalpathway into domestication.[24][27]The questions of when and where dogs were first domesticated have taxed geneticists and archaeologists for decades.[9]Genetic studies suggest a domestication process commencing over 25,000 years ago, in one or several wolf populations in either Europe, the high Arctic, or eastern Asia.[10]In 2021, aliterature reviewof the current evidenceinfersthat the dog was domesticated inSiberia23,000 years ago byancient North Siberians, then later dispersed eastward into the Americas and westward across Eurasia.[22] Breeds Main article:Dog breed Further information:Dog type  Dog breeds show a range ofphenotypic variation Dogs are the most variable mammal on earth with around 450 globally recognizeddog breeds.[10]In theVictorian era, directed humanselectiondeveloped the moderndog breeds, which resulted in a vast range of phenotypes.[8]Most breeds were derived from small numbers of founders within the last 200 years,[8][10]and since then dogs have undergone rapidphenotypicchange and were formed into today's modern breeds due toartificial selectionimposed by humans. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour.[8]Their behavioural traits include guarding, herding, and hunting,[8]retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression,[10]which demonstrates the functional and behavioral diversity of dogs.[8]As a result, present day dogs are the most abundant carnivore species and are dispersed around the world.[10]The most striking example of this dispersal is that of the numerous modern breeds of European lineage during theVictorian era.[7] Biology Anatomy Main article:Dog anatomy Skeleton  A lateral view of a dog skeleton All healthy dogs, regardless of their size and type, have an identicalskeletalstructure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types.[28][29]The dog's skeleton is well adapted for running; thevertebraeon the neck and back have extensions for powerful back muscles to connect to, the long ribs provide plenty of room for the heart and lungs, and the shoulders are unattached to the skeleton allowing great flexibility.[28][29] Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog's skeleton greatly enhanced in size for larger types asmastiffsand miniaturised for smaller types such asterriers;dwarfismhas been selectively utilised for some types where short legs are advantageous such asdachshundsandcorgis.[29]Most dogs naturally have 26 vertebrae in their tails, but some withnaturally short tailshave as few as three.[28] The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types.[29][30]The three basic skull shapes are the elongated dolichocephalic type as seen insighthounds, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls.[29][30] Senses Further information:Dog anatomy §Senses A dog's senses include vision, hearing, smell, taste, touch, and sensitivity to Earth's magnetic field. Another study has suggested that dogs can see Earth's magnetic field.[31] Coat Main article:Dog coat  Dogs display wide variation in coat type, density, length, color, and composition Thecoatsof domestic dogs are of two varieties: "double" being familiar with dogs (as well as wolves) originating from colder climates, made up of a coarseguard hairand a softdown hair, or "single", with the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" of white fur on their chest or underside.[32]Premature graying can occur in dogs from as early as one year of age; this is associated withimpulsive behaviors,anxiety behaviors, fear of noise, and fear of unfamiliar people or animals.[33] Tail There are many different shapes fordog tails: straight, straight up, sickle, curled, or corkscrew. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be crucial in getting along with others. In some hunting dogs the tail is traditionallydockedto avoid injuries. Health Main article:Dog health Some breeds of dogs are prone to specific genetic ailments such aselbowandhip dysplasia,blindness,deafness,pulmonic stenosis,cleft palate, andtrick knees. Two severe medical conditions significantly affecting dogs arepyometra, affectingunspayedfemales of all breeds and ages, andGastric dilatation volvulus(bloat), which affects larger breeds or deep-chested dogs. Both of these are acute conditions and can kill rapidly. Dogs are also susceptible to parasites such asfleas,ticks,mites,hookworms,tapeworms,roundworms, andheartworms, which is aroundwormspecies that lives in the hearts of dogs. Several human foods and household ingestibles are toxic to dogs, includingchocolate solids, causingtheobromine poisoning,onionsandgarlic, causingthiosulphate,sulfoxideordisulfidepoisoning,grapesandraisins,macadamia nuts, andxylitol.[34]The nicotine in tobacco can also be dangerous to dogs. Signs of ingestion can include copious vomiting (e.g., from eating cigar butts) ordiarrhea. Some other symptoms are abdominal pain, loss of coordination, collapse, or death.[35][pageneeded] Dogs are also vulnerable to some of the same health conditions as humans, includingdiabetes,dentalandheart disease,epilepsy,cancer,hypothyroidism, andarthritis. Lifespan Further information:Aging in dogs The typical lifespan of dogs varies widely among breeds, but for most, the median longevity (the age at which half the dogs in a population have died and half are still alive) ranges from 10 to 13 years.[36][37]The median longevity ofmixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[36][37][38]For dogs in England, increased body weight has been found to be negatively correlated with longevity (i.e., the heavier the dog, the shorter its lifespan), andmixed-breed dogslive on average 1.2 years longer thanpurebred dogs.[39] Reproduction Main article:Canine reproduction  A female dog nursing newborn puppies. In domestic dogs,sexual maturityhappens around six months to one year for both males and females, although this can be delayed until up to two years of age for some large breeds, and is the time at which female dogs will have their firstestrous cycle. They will experience subsequent estrous cycles semiannually, during which the body prepares forpregnancy. At the peak of the cycle, females will become estrous, mentally and physically receptive tocopulation. Because theovasurvive and can be fertilized for a week after ovulation, more than one male can sire the same litter.[12] Fertilization typically occurs two to five days after ovulation; 14–16 days after ovulation, the embryo attaches to the uterus and after seven to eight more days, a heartbeat is detectable.[40][41] Dogs bear their litters roughly 58 to 68 days afterfertilization,[12][42]with an average of 63 days, although the length of gestation can vary. An average litter consists of about sixpuppies.[43] Neutering Neuteringrefers to the sterilization of animals, usually byremoving the male's testiclesor the female'sovariesanduterus, to eliminate the ability to procreate and reducesex drive. Because ofdogs' overpopulationin some countries, many animal control agencies, such as theAmerican Society for the Prevention of Cruelty to Animals(ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized.[44] According to theHumane Society of the United States, three to four million dogs and cats areeuthanizedeach year.[45]Many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down.[46] Neutering reduces problems caused byhypersexuality, especially in male dogs.[47]Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs.[48][pageneeded]However, neutering increases the risk ofurinary incontinencein female dogs[49]andprostate cancerin males[50]andosteosarcoma,hemangiosarcoma,cruciate ligamentrupture, obesity, anddiabetes mellitusin either sex.[51] Inbreeding depression A common breeding practice for pet dogs is mating between close relatives (e.g., between half and full siblings).[52]Inbreeding depressionis considered to be due mainly to the expression of homozygous deleterious recessive mutations.[53]Outcrossing between unrelated individuals, including dogs of different breeds, results in the beneficial masking of deleterious recessive mutations in progeny.[54] In a study of seven dog breeds (theBernese Mountain Dog,Basset Hound,Cairn Terrier,Brittany,German Shepherd Dog,Leonberger, andWest Highland White Terrier), it was found that inbreeding decreases litter size and survival.[55]Another analysis of data on 42,855Dachshundlitters found that as theinbreeding coefficientincreased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression.[56]In a study ofBoxerlitters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.[57] Behavior Main article:Dog behavior See also:Dog behavior §Behavior compared with other canids Dog behavior is the internally coordinated responses (actions or inactions) of the domestic dog (individuals or groups) to internal and external stimuli.[58]As the oldest domesticated species, dogs' minds inevitably have been shaped by millennia of contact with humans. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans more than any other species and they are uniquely attuned to human behaviors.[13]Behavioral scientists have uncovered a surprising set of social-cognitive abilities in domestic dogs. These abilities are not possessed by the dog's closest canine relatives or other highly intelligent mammals, such asgreat apes, but rather parallel to children's social-cognitive skills.[59] Unlike other domestic species selected for production-related traits, dogs were initially selected for their behaviors.[60][61]In 2016, a study found that only 11 fixed genes showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect thecatecholamine synthesispathway, with the majority of the genes affecting the fight-or-flight response[61][62](i.e., selection for tameness) and emotional processing.[61]Dogs generally show reduced fear and aggression compared with wolves.[61][63]Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and later in breed formation.[61]Traits of high sociability and lack of fear in dogs may include genetic modifications related toWilliams-Beuren syndromein humans, which causehypersociabilityat the expense of problem-solving ability.[64] Intelligence Main article:Dog intelligence Dog intelligence is the dog's ability to perceive information and retain it as knowledge for applying to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills. A study withRico, aBorder Collie, showed that he knew the labels of over 200 different items. He inferred the names of novel things by exclusion learning and correctly retrieved those new items immediately and four weeks after the initial exposure. A study of another Border Collie, Chaser, documented his learning and memory capabilities. He had learned the names and could associate by verbal command over 1,000 words.[65]Dogs can read and react appropriately to human body language such as gesturing and pointing and human voice commands. One study of canine cognitive abilities found that dogs' capabilities are no more exceptional than those of other animals, such ashorses,chimpanzees, orcats.[66]One limited study of 18 household dogs found that they lacked spatial memory, and were more focussed on the "what" of a task rather than the "where".[67] Dogs demonstrate atheory of mindby engaging in deception.[68]An experimental study showed compelling evidence that Australiandingoscan outperform domestic dogs in non-social problem-solving, indicating that domestic dogs may have lost much of their original problem-solving abilities once they joined humans.[69]Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an unsolvable version of the same problem look at the human, while socialized wolves do not.[70] Communication Main article:Dog communication  Dog sounds 0:15 A dog making noises and barking Problems playing this file? Seemedia help. Dog communication is how dogs convey information to other dogs, understand messages from humans and translate the information that dogs are transmitting.[71]: xii Communication behaviors of dogs include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs), and gustatory communication (scents, pheromones, and taste). Humans communicate to dogs by using vocalization, hand signals, and body posture. Ecology Population The dog is probably the most widely abundant largecarnivoranliving in the human environment.[72][73]In 2013, the estimated global dog population was between 700 million[74]and 987 million.[75]About 20% of dogs live as pets in developed countries.[76]In the developing world, dogs are more commonly feral or communally owned, with pet dogs uncommon. Most of these dogs live their lives as scavengers and have never been owned by humans, with one study showing their most common response when approached by strangers is to run away (52%) or respond aggressively (11%).[77]Little is known about these dogs, or the dogs in developed countries that are feral, strays, or are in shelters because the great majority of modern research on dog cognition has focused on pet dogs living in human homes.[78] Competitors and predators Although dogs are the most abundant and widely distributed terrestrial carnivores, feral andfree-ranging dogs' potentialto compete with other large carnivores is limited by their strong association with humans.[72]For example, a review of the studies in dogs' competitive effects onsympatriccarnivores did not mention any research on competition between dogs and wolves.[79][80]Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups.[79][81] Wolves kill dogs wherever they are found together.[82]In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs to the extent that they have to be beaten off or killed.[83]Although the numbers of dogs killed each year are relatively low, it induces a fear of wolves entering villages and farmyards to take dogs and losses of dogs to wolves have led to demands for more liberal wolf hunting regulations.[79] Coyotesandbig catshave also been known to attack dogs. In particular,leopardsare known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size.[84]Siberian tigersin theAmur Riverregion have killed dogs in the middle of villages. This indicates that the dogs were targeted. Amur tigers will not tolerate wolves as competitors within their territories, and the tigers could be considering dogs in the same way.[85]Striped hyenasare known to kill dogs in their range.[86] Diet See also:Dog food  AGolden Retrievergnawing on a pig's foot Dogs have been described asomnivores.[12][87][88]Compared to wolves, dogs from agricultural societies haveextra copies of amylaseand other genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet.[11]Similar to humans, some dog breeds produce amylase in theirsalivaand are classified as having a high starch diet.[89]However, more like cats and less like other omnivores, dogs can only producebile acidwithtaurineand they cannot producevitamin D, which they obtain from animal flesh. Also more like cats, dogs requirearginineto maintain its nitrogen balance. These nutritional requirements place dogs halfway between carnivores and omnivores.[90] Range As a domesticated or semi-domesticated animal, the dog is nearly universal among human societies. Notable exceptions once included: TheAboriginal Tasmanians, who were separated from Australia before the arrival ofdingoson that continent TheAndamanese peoples, who were isolated whenrising sea levelscovered the land bridge to Myanmar TheFuegians, who instead domesticated theFuegian dog, a different canid species Individual Pacific islands whose maritime settlers did not bring dogs, or where dogs died out after original settlement, notably theMariana Islands,[91]Palau[92]and most of theCaroline Islandswith exceptions such asFais IslandandNukuoro,[93]theMarshall Islands,[94]theGilbert Islands,[94]New Caledonia,[95]Vanuatu,[95][96]Tonga,[96]Marquesas,[96]Mangaiain theCook Islands,Rapa ItiinFrench Polynesia,Easter Island,[96]theChatham Islands[97]andPitcairn Island(settled by theBountymutineers, who killed off their dogs to escape discovery by passing ships).[98] Dogs were introduced toAntarcticaassled dogs, but were later outlawed by international agreement due to the possible risk of spreading infections.[99] Roles with humans Domestic dogs inherited complex behaviors, such asbite inhibition, from their wolf ancestors, which would have beenpack hunterswith a complex body language. These sophisticated forms of social cognition and communication may account for their trainability, playfulness and ability to fit into human households and social situations. These attributes have given dogs a relationship with humans that has enabled them to become one of the most successful animals today.[100] The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such ashunting,herding,pulling loads,protection,assisting policeand themilitary,companionshipandaiding disabled individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogsare also a source of meat.[101][102] Pets  Siberian Huskiesarepack animalsthat still enjoy some human companionship It is estimated that three-quarters of the world's dog population lives in the developing world as feral, village, or community dogs, with pet dogs uncommon.[103][pageneeded] "The most widespread form of interspecies bonding occurs between humans and dogs"[104]and the keeping of dogs as companions, particularly by elites, has a long history.[14]Pet dog populations grew significantly afterWorld War IIas suburbanization increased.[14]In the 1950s and 1960s, dogs were kept outside more often than they tend to be today[105](the expression "in the doghouse" - recorded since 1932[106]- to describe exclusion from the group implies a distance between thedoghouseand the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the pet dog's role, such as the increased role of dogs in the emotional support of their human guardians.[107][pageneeded]People and their dogs have become increasingly integrated and implicated in each other's lives[108][pageneeded]to the point where pet dogs actively shape how a family and home are experienced.[109] There have been two significant trends occurring within the second half of the 20th century in pet dogs' changing status. The first has been"commodification", shaping it to conform to social expectations of personality and behavior.[109]The second has been the broadening of the family's concept and the home to include dogs-as-dogs within everyday routines and practices.[109] A vast range of commodity forms aims to transform a pet dog into an ideal companion.[110]The list of goods, services, and places available is enormous: from dog perfumes, couture, furniture and housing to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches and dog hotels, airlines and cemeteries.[110]Dog training books, classes, and television programs proliferated as the process of commodifying the pet dog continued.[111] The majority of contemporary dog owners describe their pet as part of the family, although some ambivalence about the relationship is evident in the popular reconceptualization of the dog-human family as a pack.[109]Some dog trainers, such as on the television programDog Whisperer, have promoted adominance modelof dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions.[112]The idea of the "alpha dog" trying to be dominant is based on a disproved theory about wolf packs.[113][114]Pet dogs play an active role in family life; for example, a study of conversations in dog-human families showed how family members use the dog as a resource, talking to the dog, or talking through the dog; to mediate their interactions with each other.[115] Increasingly, human family-members engage in activities centered on the dog's perceived needs and interests, or in which the dog is an integral partner, such asdog dancinganddog yoga.[110] According to statistics published by theAmerican Pet Products Manufacturers Associationin the National Pet Owner Survey in 2009–2010, an estimated 77.5million people in the United States have pet dogs.[116]The same source shows that nearly 40% of American households own at least one dog, of which 67% own just one dog, 25% two dogs and nearly 9% more than two dogs. There does not seem to be anygender preferenceamong dogs as pets, as the statistical data reveal an equal number of male and female pet dogs. Although several programs promotepet adoption, less than one-fifth of the owned dogs come fromshelters.[116] A study usingmagnetic resonance imaging(MRI) to compare humans and dogs showed that dogs have the same response to voices and use the same parts of the brain as humans do. This gives dogs the ability to recognize human emotional sounds, making them friendly social pets to humans.[117] Workers Dogs have lived and worked with humans in many roles. In addition to dogs' role as companion animals, dogs have been bred for herding livestock (collies,sheepdogs),[118][pageneeded][12]hunting (hounds, pointers)[119][pageneeded]and rodent control (terriers).[12]Other types ofworking dogsincludesearch and rescue dogs,[120]detection dogstrained to detectillicit drugs[121]orchemical weapons;[122]guard dogs; dogs who assist fishermen with the use of nets; and dogs that pull loads.[12]In 1957, the dogLaikabecame the first animal to be launched intoEarth orbit, aboard theSoviets'Sputnik 2; she died during the flight.[123][124] Various kinds ofservice dogsandassistance dogs, includingguide dogs,hearing dogs,mobility assistance dogsandpsychiatric service dogs, assist individuals with disabilities.[125][126]Some dogs owned by people with epilepsy have been shown to alert their handler when the handler shows signs of an impending seizure, sometimes well in advance of onset, allowing the guardian to seek safety, medication, or medical care.[127] Athletes and models See also:Conformation show People often enter their dogs in competitions, such as breed-conformation shows orsports, including racing, sledding and agility competitions. In conformation shows, also referred to as breed shows, a judge familiar with the specific dog breed evaluates individual purebred dogs for conformity with their established breed type as described in the breed standard. As the breed standard only deals with the dog's externally observable qualities (such as appearance, movement and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows. Food Main article:Dog meat Dog meat is consumed in someEast Asiancountries, includingKorea,[128][pageneeded]China,[101]Vietnam[102]and thePhilippines,[129]which dates back to antiquity.[130]Based on limited data, it is estimated that 13–16million dogs are killed and consumed in Asia every year.[131]In China, debates have ensued over banning the consumption of dog meat.[132]Following the Sui and Tang dynasties of the first millennium, however, people living on northern China's plains began to eschew eating dogs, which is likely due to Buddhism and Islam's spread, two religions that forbade the consumption of certain animals, including the dog. As members of the upper classes shunned dog meat, it gradually became a social taboo to eat it, even though the general population continued to consume it for centuries afterward.[133]Dog meat is also consumed in some parts of Switzerland.[134]Other cultures, such asPolynesiaandpre-Columbian Mexico, also consumed dog meat in their history. Dog fat is also reportedly believed to be beneficial for the lungs in some parts of Poland[135][136]and Central Asia.[137][138]Proponents of eating dog meat have argued that placing a distinction between livestock and dogs is Western hypocrisy and that there is no difference in eating different animals' meat.[139][140][141][142] In Korea, the primary dog breed raised for meat, theNureongi, differs from those breeds raised for pets that Koreans may keep in their homes.[143] The most popular Korean dog dish is calledbosintang, a spicy stew meant to balance the body's heat during the summer months. Followers of the custom claim this is done to ensure good health by balancing one'sgi, or the body's vital energy. A 19th-century version of bosintang explains that the dish is prepared by boiling dog meat withscallionsand chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still prevalent in Korea with a segment of the population, dog is not as widely consumed as beef, pork and chicken.[143] Health risks Further information:Dog bite,Canine vector-borne disease, andDog bite prevention In 2018, theWHOreported that 59,000 people died globally fromrabies, with 59.6% in Asia and 36.4% in Africa. Rabies is a disease for which dogs are the most important vector.[144]Significant dog bites affect tens of millions of people globally each year. Children in mid-to-late childhood are the largest percentage bitten by dogs, with a greater risk of injury to the head and neck. They are more likely to need medical treatment and have the highest death rate.[145]Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.[146] In theU.S.,catsand dogs are a factor in more than 86,000 falls each year.[147]It has been estimated that around 2% of dog-related injuries treated in U.K. hospitals are domestic accidents. The same study found that while dog involvement in road traffic accidents was difficult to quantify, dog-associated road accidents involving injury more commonly involved two-wheeled vehicles.[148] Toxocara canis(dogroundworm) eggs in dog feces can causetoxocariasis. In the United States, about 10,000 cases ofToxocarainfection are reported in humans each year, and almost 14% of the U.S. population is infected.[149]Untreated toxocariasis can cause retinal damage and decreased vision.[150]Dog feces can also containhookwormsthat causecutaneous larva migransin humans.[151][152] Health benefits  Walking a dog Dogs suffer from the same common disorders as humans; these include cancer, diabetes, heart disease and neurologic disorders. Their pathology is similar to humans, as is their response to treatment and their outcomes. Researchers are identifying the genes associated with dog diseases similar to human disorders, but lack mouse models to find cures for both dogs and humans. The genes involved in canine obsessive-compulsive disorders led to the detection of four genes in humans' related pathways.[10] The scientific evidence is mixed as to whether a dog's companionship can enhance human physical health and psychological well-being.[153]Studies suggesting that there are benefits to physical health and psychological well-being[154]have been criticized for being poorly controlled.[155]It found that "the health of elderly people is related to their health habits and social supports but not to their ownership of, or attachment to, a companion animal." Earlier studies have shown that people who keep pet dogs or cats exhibit better mental and physical health than those who do not, making fewer visits to the doctor and being less likely to be on medication than non-guardians.[156] A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."[153]In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition. This effect was sustained in those with dogs through to the end of the study.[157] People with pet dogs took considerably more physical exercise than those with cats and those without pets. The results provide evidence that keeping pets may have positive effects on human health and behavior and that for guardians of dogs, these effects are relatively long-term.[157]Pet guardianship has also been associated with increased coronary artery disease survival. Human guardians are significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs.[158]The association between dog ownership and adult physical activity levels has been reviewed by several authors.[159][160] The health benefits of dogs can result from contact with dogs in general, not solely from having dogs as pets. For example, when in a pet dog's presence, people show reductions in cardiovascular, behavioral and psychological indicators of anxiety.[161]Other health benefits are gained from exposure to immune-stimulating microorganisms, which can protect against allergies and autoimmune diseases according to thehygiene hypothesis. The benefits of contact with a dog also include social support, as dogs cannot only provide companionship and social support themselves but also act as facilitators of social interactions between humans.[162]One study indicated that wheelchair users experience more positive social interactions with strangers when accompanied by a dog than when they are not.[163]In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners.[164] Using dogs and other animals as a part of therapy dates back to the late 18th century, when animals were introduced into mental institutions to help socialize patients with mental disorders.[165]Animal-assisted intervention research has shown that animal-assisted therapy with a dog can increase social behaviors, such as smiling and laughing, among people with Alzheimer's disease.[166]One study demonstrated that children with ADHD and conduct disorders who participated in an education program with dogs and other animals showed increased attendance, increased knowledge and skill objectives and decreased antisocial and violent behavior compared with those not in an animal-assisted program.[167] Cultural importance Main articles:Cultural depictions of dogsandDogs in religion Further information:List of fictional dogs  Cerberus, with the gluttons inDante'sThird Circle of Hell.William Blake. Dogs were depicted to symbolizeguidance,protection,loyalty,fidelity,faithfulness,alertness, andlove.[168]In ancientMesopotamia, from theOld Babylonian perioduntil theNeo-Babylonian, dogs were the symbol ofNinisina, the goddess of healing and medicine,[169]and her worshippers frequently dedicated small models of seated dogs to her.[169]In theNeo-Assyrianand Neo-Babylonian periods, dogs were used as emblems of magical protection.[169]InChina,KoreaandJapan, dogs are viewed as kind protectors.[170] In mythology, dogs often serve as pets or as watchdogs.[170]Stories of dogs guarding the gates of the underworld recur throughout Indo-European mythologies[171][172]and may originate fromProto-Indo-European religion.[171][172]InGreek mythology,Cerberusis a three-headed,dragon-tailed watchdog who guards the gates ofHades.[170]Dogs are also associated with the Greek goddessHecate.[173]InNorse mythology, a bloody, four-eyed dog calledGarmrguardsHelheim.[170]InPersian mythology, two four-eyed dogs guard theChinvat Bridge.[170]InWelsh mythology,Annwnis guarded byCŵn Annwn.[170]InHindu mythology,Yama, the god of death, owns two watchdogs who have four eyes. They are said to watch over the gates ofNaraka.[174]A black dog is also considered to be thevahana(vehicle) ofBhairava(an incarnation of Shiva).[175] InChristianity, dogs represent faithfulness.[170]Within theRoman Catholicdenomination specifically, the iconography ofSaint Dominicincludes a dog, after the hallow's mother dreamt of a dog springing from her womb and becoming pregnant shortly after that.[176]As such, theDominican Order(Ecclesiastical Latin:Domini canis) means "dog of the Lord" or "hound of the Lord" (Ecclesiastical Latin:Domini canis).[176]In Christian folklore, achurch grimoften takes the form of a black dog to guard Christian churches and theirchurchyardsfromsacrilege.[177]Jewish lawdoes not prohibit keeping dogs and other pets.[178]Jewish law requires Jews to feed dogs (and other animals that they own) before themselves and make arrangements for feeding them before obtaining them.[178]The view on dogs inIslamis mixed, with some schools of thought viewing it as unclean,[170]althoughKhaled Abou El Fadlstates that this view is based on "pre-Islamic Arab mythology" and "a tradition to be falsely attributed to the Prophet."[179]Therefore, Sunni Malaki and Hanafi jurists permit the trade of and keeping of dogs as pets.[180]

Owlsarebirdsfrom theorderStrigiformes(/ˈstrɪdʒəfɔːrmiːz/), which includes over 200 species of mostlysolitaryandnocturnalbirds of preytypified by an upright stance, a large, broad head,binocular vision,binaural hearing, sharp talons, andfeathersadapted for silent flight. Exceptions include the diurnalnorthern hawk-owland the gregariousburrowing owl. Owl Temporal range:Late Paleoceneto recent60–0Ma PreꞒ Ꞓ O S D C P T J K Pg N LeftStrigidae:Tawny owl(Strix aluco),Eurasian eagle-owl(Bubo bubo),Little owl(Athene noctua),Northern saw-whet owl(Aegolius acadicus); RightTytonidae:Barn owl(Tyto alba),Lesser sooty owl(Tyto multipunctata),Tasmanian masked owl(Tyto novaehollandiae castanops),Sri Lanka bay owl(Phodilus assimilis).Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:AvesClade:TelluravesOrder:Strigiformes Wagler, 1830Families Strigidae Tytonidae Ogygoptyngidae(fossil) Palaeoglaucidae(fossil) Protostrigidae(fossil) Sophiornithidae(fossil) Range of the owl, all species.Synonyms StrigidaesensuSibley & Ahlquist Owls hunt mostly smallmammals,insects, and other birds, although a few species specialize in huntingfish. They are found in all regions of the Earth except the polar ice caps and some remote islands. Owls are divided into twofamilies: thetrue (or typical) owlfamily, Strigidae, and thebarn-owlfamily, Tytonidae. A group of owls is called a "parliament". Crow is a black cluar bird.

Thegoatordomestic goat(Capra hircus) is adomesticatedspecies ofgoat-antelopetypically kept aslivestock. It wasdomesticatedfrom thewild goat(C. aegagrus) ofSouthwest AsiaandEastern Europe. The goat is a member of the animal familyBovidaeand the tribeCaprini, meaning it is closely related to thesheep. There are over 300 distinctbreedsof goat.[1]It is one of the oldest domesticated species of animal, according to archaeological evidence that its earliest domestication occurred in Iran at 10,000 calibrated calendar years ago. Domestic goat Temporal range:0.01–0Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ Neolithic–Recent Apygmy goaton atree stump Conservation status Domesticated Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:ArtiodactylaFamily:BovidaeSubfamily:CaprinaeTribe:CapriniGenus:CapraSpecies: C.hircus Binomial nameCapra hircus Linnaeus,1758 Synonyms Capra aegagrus hircusLinnaeus,1758 Capra depressaLinnaeus,1758 Capra mambricaLinnaeus,1758 Capra reversaLinnaeus,1758 Goat-herding is an ancient tradition that is still important in places such as Egypt. Goats have been used formilk,meat,fur, andskinsacross much of the world.[3]Milk from goats is often turned intogoat cheese. Female goats are referred to asdoesornannies,intactmales are calledbucksorbillies, and juvenile goats of both sexes are calledkids.Castratedmales are calledwethers. While the wordshircineandcaprineboth refer to anything having a goat-like quality,hircineis used most often to emphasize the distinct smell of domestic goats. In 2011, there were more than 924 million goats living in the world, according to theUNFood and Agriculture Organization.

Thegoatordomestic goat(Capra hircus) is adomesticatedspecies ofgoat-antelopetypically kept aslivestock. It wasdomesticatedfrom thewild goat(C. aegagrus) ofSouthwest AsiaandEastern Europe. The goat is a member of the animal familyBovidaeand the tribeCaprini, meaning it is closely related to thesheep. There are over 300 distinctbreedsof goat.[1]It is one of the oldest domesticated species of animal, according to archaeological evidence that its earliest domestication occurred in Iran at 10,000 calibrated calendar years ago. Domestic goat Temporal range:0.01–0Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ Neolithic–Recent Apygmy goaton atree stump Conservation status Domesticated Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:ArtiodactylaFamily:BovidaeSubfamily:CaprinaeTribe:CapriniGenus:CapraSpecies: C.hircus Binomial nameCapra hircus Linnaeus,1758 Synonyms Capra aegagrus hircusLinnaeus,1758 Capra depressaLinnaeus,1758 Capra mambricaLinnaeus,1758 Capra reversaLinnaeus,1758 Goat-herding is an ancient tradition that is still important in places such as Egypt. Goats have been used formilk,meat,fur, andskinsacross much of the world.[3]Milk from goats is often turned intogoat cheese. Female goats are referred to asdoesornannies,intactmales are calledbucksorbillies, and juvenile goats of both sexes are calledkids.Castratedmales are calledwethers. While the wordshircineandcaprineboth refer to anything having a goat-like quality,hircineis used most often to emphasize the distinct smell of domestic goats. In 2011, there were more than 924 million goats living in the world, according to theUNFood and Agriculture Organization.

In 1758, the Swedish botanist and zoologistCarl Linnaeuspublished in hisSystema Naturae, the two-word naming of species (binomial nomenclature).Canisis theLatinword meaning "dog",[15]and under thisgenus, he listed the domestic dog, thewolf, and thegolden jackal. He classified the domestic dog asCanis familiarisand, on the next page, classified the grey wolf asCanis lupus.[2]Linnaeus considered the dog to be a separate species from the wolf because of its upturning tail (cauda recurvata), which is not found in any othercanid.[16] In 1999, a study ofmitochondrial DNA(mtDNA) indicated that the domestic dog may have originated from the grey wolf, with thedingoandNew Guinea singing dogbreeds having developed at a time when human communities were more isolated from each other.[17]In the third edition ofMammal Species of the Worldpublished in 2005, themammalogistW. Christopher Wozencraftlisted under the wolfCanis lupusits wild subspecies and proposed two additional subspecies, which formed the domestic dog clade:familiaris, as named by Linnaeus in 1758 and,dingonamed by Meyer in 1793. Wozencraft includedhallstromi(the New Guinea singing dog) as another name (junior synonym) for the dingo. Wozencraft referred to the mtDNA study as one of the guides informing his decision.[3]Mammalogists have noted the inclusion offamiliarisanddingotogether under the "domestic dog" clade[18]with some debating it.[19] In 2019, a workshop hosted by theIUCN/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to beferalCanis familiarisand therefore did not assess them for theIUCN Red List of Threatened Species.[4] Evolution Main article:Evolution of the wolf  Location of a dog'scarnassials; the inside of the 4th upperpremolaraligns with the outside of the 1st lowermolar, working like scissor blades TheCretaceous–Paleogene extinction eventoccurred 65 million years ago and brought an end to the dinosaurs and the appearance of the first carnivorans.[20]The namecarnivoranis given to a member of the orderCarnivora. Carnivorans possess a common arrangement of teeth calledcarnassials, in which the first lowermolarand the last upperpremolarpossess blade-like enamelcrownsthat act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether as in seals, sea lions, and walruses. Today, not all carnivorans arecarnivores, such as the insect-eatingAardwolf.[5] The carnivoran ancestors of the dog-likecaniformsand the cat-likefeliformsbegan their separate evolutionary paths just after the end of the dinosaurs. The first members of the dog familyCanidaeappeared 40 million years ago,[21]of which only its subfamily theCaninaesurvives today in the form of the wolf-like and fox-like canines. Within the Caninae, the first members of genusCanisappeared six million years ago,[15]the ancestors of modern domestic dogs, wolves,coyotes, and golden jackals. Domestication Main article:Domestication of the dog The earliest remains generally accepted to be those of a domesticated dog were discovered inBonn-Oberkassel, Germany. Contextual, isotopic, genetic, and morphological evidence shows that this dog was not a local wolf.[22]The dog was dated to 14,223 years ago and was found buried along with a man and a woman, all three having been sprayed with redhematitepowder and buried under large, thick basalt blocks. The dog had died ofcanine distemper.[23]Earlier remains dating back to 30,000 years ago have been described asPaleolithic dogs, but their status as dogs or wolves remains debated[24]because considerablemorphologicaldiversity existed among wolves during theLate Pleistocene.[1] This timing indicates that the dog was the first species to be domesticated[9][8]in the time ofhunter–gatherers,[7]which predates agriculture.[1]DNA sequencesshow that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from themodern wolflineage.[6][7]Most dogs form a sister group to the remains of a LatePleistocene wolffound in theKessleroch cavenearThayngenin the canton ofSchaffhausen,Switzerland, which dates to 14,500 years ago. Themost recent common ancestorof both is estimated to be from 32,100 years ago.[25]This indicates that an extinct Late Pleistocene wolf may have been the ancestor of the dog,[8][1][26]with the modern wolf being the dog's nearest living relative.[8] The dog is a classic example of a domestic animal that likely travelled acommensalpathway into domestication.[24][27]The questions of when and where dogs were first domesticated have taxed geneticists and archaeologists for decades.[9]Genetic studies suggest a domestication process commencing over 25,000 years ago, in one or several wolf populations in either Europe, the high Arctic, or eastern Asia.[10]In 2021, aliterature reviewof the current evidenceinfersthat the dog was domesticated inSiberia23,000 years ago byancient North Siberians, then later dispersed eastward into the Americas and westward across Eurasia.[22] Breeds Main article:Dog breed Further information:Dog type  Dog breeds show a range ofphenotypic variation Dogs are the most variable mammal on earth with around 450 globally recognizeddog breeds.[10]In theVictorian era, directed humanselectiondeveloped the moderndog breeds, which resulted in a vast range of phenotypes.[8]Most breeds were derived from small numbers of founders within the last 200 years,[8][10]and since then dogs have undergone rapidphenotypicchange and were formed into today's modern breeds due toartificial selectionimposed by humans. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour.[8]Their behavioural traits include guarding, herding, and hunting,[8]retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression,[10]which demonstrates the functional and behavioral diversity of dogs.[8]As a result, present day dogs are the most abundant carnivore species and are dispersed around the world.[10]The most striking example of this dispersal is that of the numerous modern breeds of European lineage during theVictorian era.[7] Biology Anatomy Main article:Dog anatomy Skeleton  A lateral view of a dog skeleton All healthy dogs, regardless of their size and type, have an identicalskeletalstructure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types.[28][29]The dog's skeleton is well adapted for running; thevertebraeon the neck and back have extensions for powerful back muscles to connect to, the long ribs provide plenty of room for the heart and lungs, and the shoulders are unattached to the skeleton allowing great flexibility.[28][29] Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog's skeleton greatly enhanced in size for larger types asmastiffsand miniaturised for smaller types such asterriers;dwarfismhas been selectively utilised for some types where short legs are advantageous such asdachshundsandcorgis.[29]Most dogs naturally have 26 vertebrae in their tails, but some withnaturally short tailshave as few as three.[28] The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types.[29][30]The three basic skull shapes are the elongated dolichocephalic type as seen insighthounds, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls.[29][30] Senses Further information:Dog anatomy §Senses A dog's senses include vision, hearing, smell, taste, touch, and sensitivity to Earth's magnetic field. Another study has suggested that dogs can see Earth's magnetic field.[31] Coat Main article:Dog coat  Dogs display wide variation in coat type, density, length, color, and composition Thecoatsof domestic dogs are of two varieties: "double" being familiar with dogs (as well as wolves) originating from colder climates, made up of a coarseguard hairand a softdown hair, or "single", with the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" of white fur on their chest or underside.[32]Premature graying can occur in dogs from as early as one year of age; this is associated withimpulsive behaviors,anxiety behaviors, fear of noise, and fear of unfamiliar people or animals.[33] Tail There are many different shapes fordog tails: straight, straight up, sickle, curled, or corkscrew. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be crucial in getting along with others. In some hunting dogs the tail is traditionallydockedto avoid injuries. Health Main article:Dog health Some breeds of dogs are prone to specific genetic ailments such aselbowandhip dysplasia,blindness,deafness,pulmonic stenosis,cleft palate, andtrick knees. Two severe medical conditions significantly affecting dogs arepyometra, affectingunspayedfemales of all breeds and ages, andGastric dilatation volvulus(bloat), which affects larger breeds or deep-chested dogs. Both of these are acute conditions and can kill rapidly. Dogs are also susceptible to parasites such asfleas,ticks,mites,hookworms,tapeworms,roundworms, andheartworms, which is aroundwormspecies that lives in the hearts of dogs. Several human foods and household ingestibles are toxic to dogs, includingchocolate solids, causingtheobromine poisoning,onionsandgarlic, causingthiosulphate,sulfoxideordisulfidepoisoning,grapesandraisins,macadamia nuts, andxylitol.[34]The nicotine in tobacco can also be dangerous to dogs. Signs of ingestion can include copious vomiting (e.g., from eating cigar butts) ordiarrhea. Some other symptoms are abdominal pain, loss of coordination, collapse, or death.[35][pageneeded] Dogs are also vulnerable to some of the same health conditions as humans, includingdiabetes,dentalandheart disease,epilepsy,cancer,hypothyroidism, andarthritis. Lifespan Further information:Aging in dogs The typical lifespan of dogs varies widely among breeds, but for most, the median longevity (the age at which half the dogs in a population have died and half are still alive) ranges from 10 to 13 years.[36][37]The median longevity ofmixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[36][37][38]For dogs in England, increased body weight has been found to be negatively correlated with longevity (i.e., the heavier the dog, the shorter its lifespan), andmixed-breed dogslive on average 1.2 years longer thanpurebred dogs.[39] Reproduction Main article:Canine reproduction  A female dog nursing newborn puppies. In domestic dogs,sexual maturityhappens around six months to one year for both males and females, although this can be delayed until up to two years of age for some large breeds, and is the time at which female dogs will have their firstestrous cycle. They will experience subsequent estrous cycles semiannually, during which the body prepares forpregnancy. At the peak of the cycle, females will become estrous, mentally and physically receptive tocopulation. Because theovasurvive and can be fertilized for a week after ovulation, more than one male can sire the same litter.[12] Fertilization typically occurs two to five days after ovulation; 14–16 days after ovulation, the embryo attaches to the uterus and after seven to eight more days, a heartbeat is detectable.[40][41] Dogs bear their litters roughly 58 to 68 days afterfertilization,[12][42]with an average of 63 days, although the length of gestation can vary. An average litter consists of about sixpuppies.[43] Neutering Neuteringrefers to the sterilization of animals, usually byremoving the male's testiclesor the female'sovariesanduterus, to eliminate the ability to procreate and reducesex drive. Because ofdogs' overpopulationin some countries, many animal control agencies, such as theAmerican Society for the Prevention of Cruelty to Animals(ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized.[44] According to theHumane Society of the United States, three to four million dogs and cats areeuthanizedeach year.[45]Many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down.[46] Neutering reduces problems caused byhypersexuality, especially in male dogs.[47]Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs.[48][pageneeded]However, neutering increases the risk ofurinary incontinencein female dogs[49]andprostate cancerin males[50]andosteosarcoma,hemangiosarcoma,cruciate ligamentrupture, obesity, anddiabetes mellitusin either sex.[51] Inbreeding depression A common breeding practice for pet dogs is mating between close relatives (e.g., between half and full siblings).[52]Inbreeding depressionis considered to be due mainly to the expression of homozygous deleterious recessive mutations.[53]Outcrossing between unrelated individuals, including dogs of different breeds, results in the beneficial masking of deleterious recessive mutations in progeny.[54] In a study of seven dog breeds (theBernese Mountain Dog,Basset Hound,Cairn Terrier,Brittany,German Shepherd Dog,Leonberger, andWest Highland White Terrier), it was found that inbreeding decreases litter size and survival.[55]Another analysis of data on 42,855Dachshundlitters found that as theinbreeding coefficientincreased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression.[56]In a study ofBoxerlitters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.[57] Behavior Main article:Dog behavior See also:Dog behavior §Behavior compared with other canids Dog behavior is the internally coordinated responses (actions or inactions) of the domestic dog (individuals or groups) to internal and external stimuli.[58]As the oldest domesticated species, dogs' minds inevitably have been shaped by millennia of contact with humans. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans more than any other species and they are uniquely attuned to human behaviors.[13]Behavioral scientists have uncovered a surprising set of social-cognitive abilities in domestic dogs. These abilities are not possessed by the dog's closest canine relatives or other highly intelligent mammals, such asgreat apes, but rather parallel to children's social-cognitive skills.[59] Unlike other domestic species selected for production-related traits, dogs were initially selected for their behaviors.[60][61]In 2016, a study found that only 11 fixed genes showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect thecatecholamine synthesispathway, with the majority of the genes affecting the fight-or-flight response[61][62](i.e., selection for tameness) and emotional processing.[61]Dogs generally show reduced fear and aggression compared with wolves.[61][63]Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and later in breed formation.[61]Traits of high sociability and lack of fear in dogs may include genetic modifications related toWilliams-Beuren syndromein humans, which causehypersociabilityat the expense of problem-solving ability.[64] Intelligence Main article:Dog intelligence Dog intelligence is the dog's ability to perceive information and retain it as knowledge for applying to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills. A study withRico, aBorder Collie, showed that he knew the labels of over 200 different items. He inferred the names of novel things by exclusion learning and correctly retrieved those new items immediately and four weeks after the initial exposure. A study of another Border Collie, Chaser, documented his learning and memory capabilities. He had learned the names and could associate by verbal command over 1,000 words.[65]Dogs can read and react appropriately to human body language such as gesturing and pointing and human voice commands. One study of canine cognitive abilities found that dogs' capabilities are no more exceptional than those of other animals, such ashorses,chimpanzees, orcats.[66]One limited study of 18 household dogs found that they lacked spatial memory, and were more focussed on the "what" of a task rather than the "where".[67] Dogs demonstrate atheory of mindby engaging in deception.[68]An experimental study showed compelling evidence that Australiandingoscan outperform domestic dogs in non-social problem-solving, indicating that domestic dogs may have lost much of their original problem-solving abilities once they joined humans.[69]Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an unsolvable version of the same problem look at the human, while socialized wolves do not.[70] Communication Main article:Dog communication  Dog sounds 0:15 A dog making noises and barking Problems playing this file? Seemedia help. Dog communication is how dogs convey information to other dogs, understand messages from humans and translate the information that dogs are transmitting.[71]: xii Communication behaviors of dogs include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs), and gustatory communication (scents, pheromones, and taste). Humans communicate to dogs by using vocalization, hand signals, and body posture. Ecology Population The dog is probably the most widely abundant largecarnivoranliving in the human environment.[72][73]In 2013, the estimated global dog population was between 700 million[74]and 987 million.[75]About 20% of dogs live as pets in developed countries.[76]In the developing world, dogs are more commonly feral or communally owned, with pet dogs uncommon. Most of these dogs live their lives as scavengers and have never been owned by humans, with one study showing their most common response when approached by strangers is to run away (52%) or respond aggressively (11%).[77]Little is known about these dogs, or the dogs in developed countries that are feral, strays, or are in shelters because the great majority of modern research on dog cognition has focused on pet dogs living in human homes.[78] Competitors and predators Although dogs are the most abundant and widely distributed terrestrial carnivores, feral andfree-ranging dogs' potentialto compete with other large carnivores is limited by their strong association with humans.[72]For example, a review of the studies in dogs' competitive effects onsympatriccarnivores did not mention any research on competition between dogs and wolves.[79][80]Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups.[79][81] Wolves kill dogs wherever they are found together.[82]In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs to the extent that they have to be beaten off or killed.[83]Although the numbers of dogs killed each year are relatively low, it induces a fear of wolves entering villages and farmyards to take dogs and losses of dogs to wolves have led to demands for more liberal wolf hunting regulations.[79] Coyotesandbig catshave also been known to attack dogs. In particular,leopardsare known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size.[84]Siberian tigersin theAmur Riverregion have killed dogs in the middle of villages. This indicates that the dogs were targeted. Amur tigers will not tolerate wolves as competitors within their territories, and the tigers could be considering dogs in the same way.[85]Striped hyenasare known to kill dogs in their range.[86] Diet See also:Dog food  AGolden Retrievergnawing on a pig's foot Dogs have been described asomnivores.[12][87][88]Compared to wolves, dogs from agricultural societies haveextra copies of amylaseand other genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet.[11]Similar to humans, some dog breeds produce amylase in theirsalivaand are classified as having a high starch diet.[89]However, more like cats and less like other omnivores, dogs can only producebile acidwithtaurineand they cannot producevitamin D, which they obtain from animal flesh. Also more like cats, dogs requirearginineto maintain its nitrogen balance. These nutritional requirements place dogs halfway between carnivores and omnivores.[90] Range As a domesticated or semi-domesticated animal, the dog is nearly universal among human societies. Notable exceptions once included: TheAboriginal Tasmanians, who were separated from Australia before the arrival ofdingoson that continent TheAndamanese peoples, who were isolated whenrising sea levelscovered the land bridge to Myanmar TheFuegians, who instead domesticated theFuegian dog, a different canid species Individual Pacific islands whose maritime settlers did not bring dogs, or where dogs died out after original settlement, notably theMariana Islands,[91]Palau[92]and most of theCaroline Islandswith exceptions such asFais IslandandNukuoro,[93]theMarshall Islands,[94]theGilbert Islands,[94]New Caledonia,[95]Vanuatu,[95][96]Tonga,[96]Marquesas,[96]Mangaiain theCook Islands,Rapa ItiinFrench Polynesia,Easter Island,[96]theChatham Islands[97]andPitcairn Island(settled by theBountymutineers, who killed off their dogs to escape discovery by passing ships).[98] Dogs were introduced toAntarcticaassled dogs, but were later outlawed by international agreement due to the possible risk of spreading infections.[99] Roles with humans Domestic dogs inherited complex behaviors, such asbite inhibition, from their wolf ancestors, which would have beenpack hunterswith a complex body language. These sophisticated forms of social cognition and communication may account for their trainability, playfulness and ability to fit into human households and social situations. These attributes have given dogs a relationship with humans that has enabled them to become one of the most successful animals today.[100] The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such ashunting,herding,pulling loads,protection,assisting policeand themilitary,companionshipandaiding disabled individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogsare also a source of meat.[101][102] Pets  Siberian Huskiesarepack animalsthat still enjoy some human companionship It is estimated that three-quarters of the world's dog population lives in the developing world as feral, village, or community dogs, with pet dogs uncommon.[103][pageneeded] "The most widespread form of interspecies bonding occurs between humans and dogs"[104]and the keeping of dogs as companions, particularly by elites, has a long history.[14]Pet dog populations grew significantly afterWorld War IIas suburbanization increased.[14]In the 1950s and 1960s, dogs were kept outside more often than they tend to be today[105](the expression "in the doghouse" - recorded since 1932[106]- to describe exclusion from the group implies a distance between thedoghouseand the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the pet dog's role, such as the increased role of dogs in the emotional support of their human guardians.[107][pageneeded]People and their dogs have become increasingly integrated and implicated in each other's lives[108][pageneeded]to the point where pet dogs actively shape how a family and home are experienced.[109] There have been two significant trends occurring within the second half of the 20th century in pet dogs' changing status. The first has been"commodification", shaping it to conform to social expectations of personality and behavior.[109]The second has been the broadening of the family's concept and the home to include dogs-as-dogs within everyday routines and practices.[109] A vast range of commodity forms aims to transform a pet dog into an ideal companion.[110]The list of goods, services, and places available is enormous: from dog perfumes, couture, furniture and housing to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches and dog hotels, airlines and cemeteries.[110]Dog training books, classes, and television programs proliferated as the process of commodifying the pet dog continued.[111] The majority of contemporary dog owners describe their pet as part of the family, although some ambivalence about the relationship is evident in the popular reconceptualization of the dog-human family as a pack.[109]Some dog trainers, such as on the television programDog Whisperer, have promoted adominance modelof dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions.[112]The idea of the "alpha dog" trying to be dominant is based on a disproved theory about wolf packs.[113][114]Pet dogs play an active role in family life; for example, a study of conversations in dog-human families showed how family members use the dog as a resource, talking to the dog, or talking through the dog; to mediate their interactions with each other.[115] Increasingly, human family-members engage in activities centered on the dog's perceived needs and interests, or in which the dog is an integral partner, such asdog dancinganddog yoga.[110] According to statistics published by theAmerican Pet Products Manufacturers Associationin the National Pet Owner Survey in 2009–2010, an estimated 77.5million people in the United States have pet dogs.[116]The same source shows that nearly 40% of American households own at least one dog, of which 67% own just one dog, 25% two dogs and nearly 9% more than two dogs. There does not seem to be anygender preferenceamong dogs as pets, as the statistical data reveal an equal number of male and female pet dogs. Although several programs promotepet adoption, less than one-fifth of the owned dogs come fromshelters.[116] A study usingmagnetic resonance imaging(MRI) to compare humans and dogs showed that dogs have the same response to voices and use the same parts of the brain as humans do. This gives dogs the ability to recognize human emotional sounds, making them friendly social pets to humans.[117] Workers Dogs have lived and worked with humans in many roles. In addition to dogs' role as companion animals, dogs have been bred for herding livestock (collies,sheepdogs),[118][pageneeded][12]hunting (hounds, pointers)[119][pageneeded]and rodent control (terriers).[12]Other types ofworking dogsincludesearch and rescue dogs,[120]detection dogstrained to detectillicit drugs[121]orchemical weapons;[122]guard dogs; dogs who assist fishermen with the use of nets; and dogs that pull loads.[12]In 1957, the dogLaikabecame the first animal to be launched intoEarth orbit, aboard theSoviets'Sputnik 2; she died during the flight.[123][124] Various kinds ofservice dogsandassistance dogs, includingguide dogs,hearing dogs,mobility assistance dogsandpsychiatric service dogs, assist individuals with disabilities.[125][126]Some dogs owned by people with epilepsy have been shown to alert their handler when the handler shows signs of an impending seizure, sometimes well in advance of onset, allowing the guardian to seek safety, medication, or medical care.[127] Athletes and models See also:Conformation show People often enter their dogs in competitions, such as breed-conformation shows orsports, including racing, sledding and agility competitions. In conformation shows, also referred to as breed shows, a judge familiar with the specific dog breed evaluates individual purebred dogs for conformity with their established breed type as described in the breed standard. As the breed standard only deals with the dog's externally observable qualities (such as appearance, movement and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows. Food Main article:Dog meat Dog meat is consumed in someEast Asiancountries, includingKorea,[128][pageneeded]China,[101]Vietnam[102]and thePhilippines,[129]which dates back to antiquity.[130]Based on limited data, it is estimated that 13–16million dogs are killed and consumed in Asia every year.[131]In China, debates have ensued over banning the consumption of dog meat.[132]Following the Sui and Tang dynasties of the first millennium, however, people living on northern China's plains began to eschew eating dogs, which is likely due to Buddhism and Islam's spread, two religions that forbade the consumption of certain animals, including the dog. As members of the upper classes shunned dog meat, it gradually became a social taboo to eat it, even though the general population continued to consume it for centuries afterward.[133]Dog meat is also consumed in some parts of Switzerland.[134]Other cultures, such asPolynesiaandpre-Columbian Mexico, also consumed dog meat in their history. Dog fat is also reportedly believed to be beneficial for the lungs in some parts of Poland[135][136]and Central Asia.[137][138]Proponents of eating dog meat have argued that placing a distinction between livestock and dogs is Western hypocrisy and that there is no difference in eating different animals' meat.[139][140][141][142] In Korea, the primary dog breed raised for meat, theNureongi, differs from those breeds raised for pets that Koreans may keep in their homes.[143] The most popular Korean dog dish is calledbosintang, a spicy stew meant to balance the body's heat during the summer months. Followers of the custom claim this is done to ensure good health by balancing one'sgi, or the body's vital energy. A 19th-century version of bosintang explains that the dish is prepared by boiling dog meat withscallionsand chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still prevalent in Korea with a segment of the population, dog is not as widely consumed as beef, pork and chicken.[143] Health risks Further information:Dog bite,Canine vector-borne disease, andDog bite prevention In 2018, theWHOreported that 59,000 people died globally fromrabies, with 59.6% in Asia and 36.4% in Africa. Rabies is a disease for which dogs are the most important vector.[144]Significant dog bites affect tens of millions of people globally each year. Children in mid-to-late childhood are the largest percentage bitten by dogs, with a greater risk of injury to the head and neck. They are more likely to need medical treatment and have the highest death rate.[145]Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.[146] In theU.S.,catsand dogs are a factor in more than 86,000 falls each year.[147]It has been estimated that around 2% of dog-related injuries treated in U.K. hospitals are domestic accidents. The same study found that while dog involvement in road traffic accidents was difficult to quantify, dog-associated road accidents involving injury more commonly involved two-wheeled vehicles.[148] Toxocara canis(dogroundworm) eggs in dog feces can causetoxocariasis. In the United States, about 10,000 cases ofToxocarainfection are reported in humans each year, and almost 14% of the U.S. population is infected.[149]Untreated toxocariasis can cause retinal damage and decreased vision.[150]Dog feces can also containhookwormsthat causecutaneous larva migransin humans.[151][152] Health benefits  Walking a dog Dogs suffer from the same common disorders as humans; these include cancer, diabetes, heart disease and neurologic disorders. Their pathology is similar to humans, as is their response to treatment and their outcomes. Researchers are identifying the genes associated with dog diseases similar to human disorders, but lack mouse models to find cures for both dogs and humans. The genes involved in canine obsessive-compulsive disorders led to the detection of four genes in humans' related pathways.[10] The scientific evidence is mixed as to whether a dog's companionship can enhance human physical health and psychological well-being.[153]Studies suggesting that there are benefits to physical health and psychological well-being[154]have been criticized for being poorly controlled.[155]It found that "the health of elderly people is related to their health habits and social supports but not to their ownership of, or attachment to, a companion animal." Earlier studies have shown that people who keep pet dogs or cats exhibit better mental and physical health than those who do not, making fewer visits to the doctor and being less likely to be on medication than non-guardians.[156] A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."[153]In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition. This effect was sustained in those with dogs through to the end of the study.[157] People with pet dogs took considerably more physical exercise than those with cats and those without pets. The results provide evidence that keeping pets may have positive effects on human health and behavior and that for guardians of dogs, these effects are relatively long-term.[157]Pet guardianship has also been associated with increased coronary artery disease survival. Human guardians are significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs.[158]The association between dog ownership and adult physical activity levels has been reviewed by several authors.[159][160] The health benefits of dogs can result from contact with dogs in general, not solely from having dogs as pets. For example, when in a pet dog's presence, people show reductions in cardiovascular, behavioral and psychological indicators of anxiety.[161]Other health benefits are gained from exposure to immune-stimulating microorganisms, which can protect against allergies and autoimmune diseases according to thehygiene hypothesis. The benefits of contact with a dog also include social support, as dogs cannot only provide companionship and social support themselves but also act as facilitators of social interactions between humans.[162]One study indicated that wheelchair users experience more positive social interactions with strangers when accompanied by a dog than when they are not.[163]In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners.[164] Using dogs and other animals as a part of therapy dates back to the late 18th century, when animals were introduced into mental institutions to help socialize patients with mental disorders.[165]Animal-assisted intervention research has shown that animal-assisted therapy with a dog can increase social behaviors, such as smiling and laughing, among people with Alzheimer's disease.[166]One study demonstrated that children with ADHD and conduct disorders who participated in an education program with dogs and other animals showed increased attendance, increased knowledge and skill objectives and decreased antisocial and violent behavior compared with those not in an animal-assisted program.[167] Cultural importance Main articles:Cultural depictions of dogsandDogs in religion Further information:List of fictional dogs  Cerberus, with the gluttons inDante'sThird Circle of Hell.William Blake. Dogs were depicted to symbolizeguidance,protection,loyalty,fidelity,faithfulness,alertness, andlove.[168]In ancientMesopotamia, from theOld Babylonian perioduntil theNeo-Babylonian, dogs were the symbol ofNinisina, the goddess of healing and medicine,[169]and her worshippers frequently dedicated small models of seated dogs to her.[169]In theNeo-Assyrianand Neo-Babylonian periods, dogs were used as emblems of magical protection.[169]InChina,KoreaandJapan, dogs are viewed as kind protectors.[170] In mythology, dogs often serve as pets or as watchdogs.[170]Stories of dogs guarding the gates of the underworld recur throughout Indo-European mythologies[171][172]and may originate fromProto-Indo-European religion.[171][172]InGreek mythology,Cerberusis a three-headed,dragon-tailed watchdog who guards the gates ofHades.[170]Dogs are also associated with the Greek goddessHecate.[173]InNorse mythology, a bloody, four-eyed dog calledGarmrguardsHelheim.[170]InPersian mythology, two four-eyed dogs guard theChinvat Bridge.[170]InWelsh mythology,Annwnis guarded byCŵn Annwn.[170]InHindu mythology,Yama, the god of death, owns two watchdogs who have four eyes. They are said to watch over the gates ofNaraka.[174]A black dog is also considered to be thevahana(vehicle) ofBhairava(an incarnation of Shiva).[175] InChristianity, dogs represent faithfulness.[170]Within theRoman Catholicdenomination specifically, the iconography ofSaint Dominicincludes a dog, after the hallow's mother dreamt of a dog springing from her womb and becoming pregnant shortly after that.[176]As such, theDominican Order(Ecclesiastical Latin:Domini canis) means "dog of the Lord" or "hound of the Lord" (Ecclesiastical Latin:Domini canis).[176]In Christian folklore, achurch grimoften takes the form of a black dog to guard Christian churches and theirchurchyardsfromsacrilege.[177]Jewish lawdoes not prohibit keeping dogs and other pets.[178]Jewish law requires Jews to feed dogs (and other animals that they own) before themselves and make arrangements for feeding them before obtaining them.[178]The view on dogs inIslamis mixed, with some schools of thought viewing it as unclean,[170]althoughKhaled Abou El Fadlstates that this view is based on "pre-Islamic Arab mythology" and "a tradition to be falsely attributed to the Prophet."[179]Therefore, Sunni Malaki and Hanafi jurists permit the trade of and keeping of dogs as pets.[180]

In 1758, the Swedish botanist and zoologistCarl Linnaeuspublished in hisSystema Naturae, the two-word naming of species (binomial nomenclature).Canisis theLatinword meaning "dog",[15]and under thisgenus, he listed the domestic dog, thewolf, and thegolden jackal. He classified the domestic dog asCanis familiarisand, on the next page, classified the grey wolf asCanis lupus.[2]Linnaeus considered the dog to be a separate species from the wolf because of its upturning tail (cauda recurvata), which is not found in any othercanid.[16] In 1999, a study ofmitochondrial DNA(mtDNA) indicated that the domestic dog may have originated from the grey wolf, with thedingoandNew Guinea singing dogbreeds having developed at a time when human communities were more isolated from each other.[17]In the third edition ofMammal Species of the Worldpublished in 2005, themammalogistW. Christopher Wozencraftlisted under the wolfCanis lupusits wild subspecies and proposed two additional subspecies, which formed the domestic dog clade:familiaris, as named by Linnaeus in 1758 and,dingonamed by Meyer in 1793. Wozencraft includedhallstromi(the New Guinea singing dog) as another name (junior synonym) for the dingo. Wozencraft referred to the mtDNA study as one of the guides informing his decision.[3]Mammalogists have noted the inclusion offamiliarisanddingotogether under the "domestic dog" clade[18]with some debating it.[19] In 2019, a workshop hosted by theIUCN/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to beferalCanis familiarisand therefore did not assess them for theIUCN Red List of Threatened Species.[4] Evolution Main article:Evolution of the wolf  Location of a dog'scarnassials; the inside of the 4th upperpremolaraligns with the outside of the 1st lowermolar, working like scissor blades TheCretaceous–Paleogene extinction eventoccurred 65 million years ago and brought an end to the dinosaurs and the appearance of the first carnivorans.[20]The namecarnivoranis given to a member of the orderCarnivora. Carnivorans possess a common arrangement of teeth calledcarnassials, in which the first lowermolarand the last upperpremolarpossess blade-like enamelcrownsthat act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether as in seals, sea lions, and walruses. Today, not all carnivorans arecarnivores, such as the insect-eatingAardwolf.[5] The carnivoran ancestors of the dog-likecaniformsand the cat-likefeliformsbegan their separate evolutionary paths just after the end of the dinosaurs. The first members of the dog familyCanidaeappeared 40 million years ago,[21]of which only its subfamily theCaninaesurvives today in the form of the wolf-like and fox-like canines. Within the Caninae, the first members of genusCanisappeared six million years ago,[15]the ancestors of modern domestic dogs, wolves,coyotes, and golden jackals. Domestication Main article:Domestication of the dog The earliest remains generally accepted to be those of a domesticated dog were discovered inBonn-Oberkassel, Germany. Contextual, isotopic, genetic, and morphological evidence shows that this dog was not a local wolf.[22]The dog was dated to 14,223 years ago and was found buried along with a man and a woman, all three having been sprayed with redhematitepowder and buried under large, thick basalt blocks. The dog had died ofcanine distemper.[23]Earlier remains dating back to 30,000 years ago have been described asPaleolithic dogs, but their status as dogs or wolves remains debated[24]because considerablemorphologicaldiversity existed among wolves during theLate Pleistocene.[1] This timing indicates that the dog was the first species to be domesticated[9][8]in the time ofhunter–gatherers,[7]which predates agriculture.[1]DNA sequencesshow that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from themodern wolflineage.[6][7]Most dogs form a sister group to the remains of a LatePleistocene wolffound in theKessleroch cavenearThayngenin the canton ofSchaffhausen,Switzerland, which dates to 14,500 years ago. Themost recent common ancestorof both is estimated to be from 32,100 years ago.[25]This indicates that an extinct Late Pleistocene wolf may have been the ancestor of the dog,[8][1][26]with the modern wolf being the dog's nearest living relative.[8] The dog is a classic example of a domestic animal that likely travelled acommensalpathway into domestication.[24][27]The questions of when and where dogs were first domesticated have taxed geneticists and archaeologists for decades.[9]Genetic studies suggest a domestication process commencing over 25,000 years ago, in one or several wolf populations in either Europe, the high Arctic, or eastern Asia.[10]In 2021, aliterature reviewof the current evidenceinfersthat the dog was domesticated inSiberia23,000 years ago byancient North Siberians, then later dispersed eastward into the Americas and westward across Eurasia.[22] Breeds Main article:Dog breed Further information:Dog type  Dog breeds show a range ofphenotypic variation Dogs are the most variable mammal on earth with around 450 globally recognizeddog breeds.[10]In theVictorian era, directed humanselectiondeveloped the moderndog breeds, which resulted in a vast range of phenotypes.[8]Most breeds were derived from small numbers of founders within the last 200 years,[8][10]and since then dogs have undergone rapidphenotypicchange and were formed into today's modern breeds due toartificial selectionimposed by humans. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour.[8]Their behavioural traits include guarding, herding, and hunting,[8]retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression,[10]which demonstrates the functional and behavioral diversity of dogs.[8]As a result, present day dogs are the most abundant carnivore species and are dispersed around the world.[10]The most striking example of this dispersal is that of the numerous modern breeds of European lineage during theVictorian era.[7] Biology Anatomy Main article:Dog anatomy Skeleton  A lateral view of a dog skeleton All healthy dogs, regardless of their size and type, have an identicalskeletalstructure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types.[28][29]The dog's skeleton is well adapted for running; thevertebraeon the neck and back have extensions for powerful back muscles to connect to, the long ribs provide plenty of room for the heart and lungs, and the shoulders are unattached to the skeleton allowing great flexibility.[28][29] Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog's skeleton greatly enhanced in size for larger types asmastiffsand miniaturised for smaller types such asterriers;dwarfismhas been selectively utilised for some types where short legs are advantageous such asdachshundsandcorgis.[29]Most dogs naturally have 26 vertebrae in their tails, but some withnaturally short tailshave as few as three.[28] The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types.[29][30]The three basic skull shapes are the elongated dolichocephalic type as seen insighthounds, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls.[29][30] Senses Further information:Dog anatomy §Senses A dog's senses include vision, hearing, smell, taste, touch, and sensitivity to Earth's magnetic field. Another study has suggested that dogs can see Earth's magnetic field.[31] Coat Main article:Dog coat  Dogs display wide variation in coat type, density, length, color, and composition Thecoatsof domestic dogs are of two varieties: "double" being familiar with dogs (as well as wolves) originating from colder climates, made up of a coarseguard hairand a softdown hair, or "single", with the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" of white fur on their chest or underside.[32]Premature graying can occur in dogs from as early as one year of age; this is associated withimpulsive behaviors,anxiety behaviors, fear of noise, and fear of unfamiliar people or animals.[33] Tail There are many different shapes fordog tails: straight, straight up, sickle, curled, or corkscrew. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be crucial in getting along with others. In some hunting dogs the tail is traditionallydockedto avoid injuries. Health Main article:Dog health Some breeds of dogs are prone to specific genetic ailments such aselbowandhip dysplasia,blindness,deafness,pulmonic stenosis,cleft palate, andtrick knees. Two severe medical conditions significantly affecting dogs arepyometra, affectingunspayedfemales of all breeds and ages, andGastric dilatation volvulus(bloat), which affects larger breeds or deep-chested dogs. Both of these are acute conditions and can kill rapidly. Dogs are also susceptible to parasites such asfleas,ticks,mites,hookworms,tapeworms,roundworms, andheartworms, which is aroundwormspecies that lives in the hearts of dogs. Several human foods and household ingestibles are toxic to dogs, includingchocolate solids, causingtheobromine poisoning,onionsandgarlic, causingthiosulphate,sulfoxideordisulfidepoisoning,grapesandraisins,macadamia nuts, andxylitol.[34]The nicotine in tobacco can also be dangerous to dogs. Signs of ingestion can include copious vomiting (e.g., from eating cigar butts) ordiarrhea. Some other symptoms are abdominal pain, loss of coordination, collapse, or death.[35][pageneeded] Dogs are also vulnerable to some of the same health conditions as humans, includingdiabetes,dentalandheart disease,epilepsy,cancer,hypothyroidism, andarthritis. Lifespan Further information:Aging in dogs The typical lifespan of dogs varies widely among breeds, but for most, the median longevity (the age at which half the dogs in a population have died and half are still alive) ranges from 10 to 13 years.[36][37]The median longevity ofmixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[36][37][38]For dogs in England, increased body weight has been found to be negatively correlated with longevity (i.e., the heavier the dog, the shorter its lifespan), andmixed-breed dogslive on average 1.2 years longer thanpurebred dogs.[39] Reproduction Main article:Canine reproduction  A female dog nursing newborn puppies. In domestic dogs,sexual maturityhappens around six months to one year for both males and females, although this can be delayed until up to two years of age for some large breeds, and is the time at which female dogs will have their firstestrous cycle. They will experience subsequent estrous cycles semiannually, during which the body prepares forpregnancy. At the peak of the cycle, females will become estrous, mentally and physically receptive tocopulation. Because theovasurvive and can be fertilized for a week after ovulation, more than one male can sire the same litter.[12] Fertilization typically occurs two to five days after ovulation; 14–16 days after ovulation, the embryo attaches to the uterus and after seven to eight more days, a heartbeat is detectable.[40][41] Dogs bear their litters roughly 58 to 68 days afterfertilization,[12][42]with an average of 63 days, although the length of gestation can vary. An average litter consists of about sixpuppies.[43] Neutering Neuteringrefers to the sterilization of animals, usually byremoving the male's testiclesor the female'sovariesanduterus, to eliminate the ability to procreate and reducesex drive. Because ofdogs' overpopulationin some countries, many animal control agencies, such as theAmerican Society for the Prevention of Cruelty to Animals(ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized.[44] According to theHumane Society of the United States, three to four million dogs and cats areeuthanizedeach year.[45]Many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down.[46] Neutering reduces problems caused byhypersexuality, especially in male dogs.[47]Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs.[48][pageneeded]However, neutering increases the risk ofurinary incontinencein female dogs[49]andprostate cancerin males[50]andosteosarcoma,hemangiosarcoma,cruciate ligamentrupture, obesity, anddiabetes mellitusin either sex.[51] Inbreeding depression A common breeding practice for pet dogs is mating between close relatives (e.g., between half and full siblings).[52]Inbreeding depressionis considered to be due mainly to the expression of homozygous deleterious recessive mutations.[53]Outcrossing between unrelated individuals, including dogs of different breeds, results in the beneficial masking of deleterious recessive mutations in progeny.[54] In a study of seven dog breeds (theBernese Mountain Dog,Basset Hound,Cairn Terrier,Brittany,German Shepherd Dog,Leonberger, andWest Highland White Terrier), it was found that inbreeding decreases litter size and survival.[55]Another analysis of data on 42,855Dachshundlitters found that as theinbreeding coefficientincreased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression.[56]In a study ofBoxerlitters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.[57] Behavior Main article:Dog behavior See also:Dog behavior §Behavior compared with other canids Dog behavior is the internally coordinated responses (actions or inactions) of the domestic dog (individuals or groups) to internal and external stimuli.[58]As the oldest domesticated species, dogs' minds inevitably have been shaped by millennia of contact with humans. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans more than any other species and they are uniquely attuned to human behaviors.[13]Behavioral scientists have uncovered a surprising set of social-cognitive abilities in domestic dogs. These abilities are not possessed by the dog's closest canine relatives or other highly intelligent mammals, such asgreat apes, but rather parallel to children's social-cognitive skills.[59] Unlike other domestic species selected for production-related traits, dogs were initially selected for their behaviors.[60][61]In 2016, a study found that only 11 fixed genes showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect thecatecholamine synthesispathway, with the majority of the genes affecting the fight-or-flight response[61][62](i.e., selection for tameness) and emotional processing.[61]Dogs generally show reduced fear and aggression compared with wolves.[61][63]Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and later in breed formation.[61]Traits of high sociability and lack of fear in dogs may include genetic modifications related toWilliams-Beuren syndromein humans, which causehypersociabilityat the expense of problem-solving ability.[64] Intelligence Main article:Dog intelligence Dog intelligence is the dog's ability to perceive information and retain it as knowledge for applying to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills. A study withRico, aBorder Collie, showed that he knew the labels of over 200 different items. He inferred the names of novel things by exclusion learning and correctly retrieved those new items immediately and four weeks after the initial exposure. A study of another Border Collie, Chaser, documented his learning and memory capabilities. He had learned the names and could associate by verbal command over 1,000 words.[65]Dogs can read and react appropriately to human body language such as gesturing and pointing and human voice commands. One study of canine cognitive abilities found that dogs' capabilities are no more exceptional than those of other animals, such ashorses,chimpanzees, orcats.[66]One limited study of 18 household dogs found that they lacked spatial memory, and were more focussed on the "what" of a task rather than the "where".[67] Dogs demonstrate atheory of mindby engaging in deception.[68]An experimental study showed compelling evidence that Australiandingoscan outperform domestic dogs in non-social problem-solving, indicating that domestic dogs may have lost much of their original problem-solving abilities once they joined humans.[69]Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an unsolvable version of the same problem look at the human, while socialized wolves do not.[70] Communication Main article:Dog communication  Dog sounds 0:15 A dog making noises and barking Problems playing this file? Seemedia help. Dog communication is how dogs convey information to other dogs, understand messages from humans and translate the information that dogs are transmitting.[71]: xii Communication behaviors of dogs include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs), and gustatory communication (scents, pheromones, and taste). Humans communicate to dogs by using vocalization, hand signals, and body posture. Ecology Population The dog is probably the most widely abundant largecarnivoranliving in the human environment.[72][73]In 2013, the estimated global dog population was between 700 million[74]and 987 million.[75]About 20% of dogs live as pets in developed countries.[76]In the developing world, dogs are more commonly feral or communally owned, with pet dogs uncommon. Most of these dogs live their lives as scavengers and have never been owned by humans, with one study showing their most common response when approached by strangers is to run away (52%) or respond aggressively (11%).[77]Little is known about these dogs, or the dogs in developed countries that are feral, strays, or are in shelters because the great majority of modern research on dog cognition has focused on pet dogs living in human homes.[78] Competitors and predators Although dogs are the most abundant and widely distributed terrestrial carnivores, feral andfree-ranging dogs' potentialto compete with other large carnivores is limited by their strong association with humans.[72]For example, a review of the studies in dogs' competitive effects onsympatriccarnivores did not mention any research on competition between dogs and wolves.[79][80]Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups.[79][81] Wolves kill dogs wherever they are found together.[82]In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs to the extent that they have to be beaten off or killed.[83]Although the numbers of dogs killed each year are relatively low, it induces a fear of wolves entering villages and farmyards to take dogs and losses of dogs to wolves have led to demands for more liberal wolf hunting regulations.[79] Coyotesandbig catshave also been known to attack dogs. In particular,leopardsare known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size.[84]Siberian tigersin theAmur Riverregion have killed dogs in the middle of villages. This indicates that the dogs were targeted. Amur tigers will not tolerate wolves as competitors within their territories, and the tigers could be considering dogs in the same way.[85]Striped hyenasare known to kill dogs in their range.[86] Diet See also:Dog food  AGolden Retrievergnawing on a pig's foot Dogs have been described asomnivores.[12][87][88]Compared to wolves, dogs from agricultural societies haveextra copies of amylaseand other genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet.[11]Similar to humans, some dog breeds produce amylase in theirsalivaand are classified as having a high starch diet.[89]However, more like cats and less like other omnivores, dogs can only producebile acidwithtaurineand they cannot producevitamin D, which they obtain from animal flesh. Also more like cats, dogs requirearginineto maintain its nitrogen balance. These nutritional requirements place dogs halfway between carnivores and omnivores.[90] Range As a domesticated or semi-domesticated animal, the dog is nearly universal among human societies. Notable exceptions once included: TheAboriginal Tasmanians, who were separated from Australia before the arrival ofdingoson that continent TheAndamanese peoples, who were isolated whenrising sea levelscovered the land bridge to Myanmar TheFuegians, who instead domesticated theFuegian dog, a different canid species Individual Pacific islands whose maritime settlers did not bring dogs, or where dogs died out after original settlement, notably theMariana Islands,[91]Palau[92]and most of theCaroline Islandswith exceptions such asFais IslandandNukuoro,[93]theMarshall Islands,[94]theGilbert Islands,[94]New Caledonia,[95]Vanuatu,[95][96]Tonga,[96]Marquesas,[96]Mangaiain theCook Islands,Rapa ItiinFrench Polynesia,Easter Island,[96]theChatham Islands[97]andPitcairn Island(settled by theBountymutineers, who killed off their dogs to escape discovery by passing ships).[98] Dogs were introduced toAntarcticaassled dogs, but were later outlawed by international agreement due to the possible risk of spreading infections.[99] Roles with humans Domestic dogs inherited complex behaviors, such asbite inhibition, from their wolf ancestors, which would have beenpack hunterswith a complex body language. These sophisticated forms of social cognition and communication may account for their trainability, playfulness and ability to fit into human households and social situations. These attributes have given dogs a relationship with humans that has enabled them to become one of the most successful animals today.[100] The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such ashunting,herding,pulling loads,protection,assisting policeand themilitary,companionshipandaiding disabled individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogsare also a source of meat.[101][102] Pets  Siberian Huskiesarepack animalsthat still enjoy some human companionship It is estimated that three-quarters of the world's dog population lives in the developing world as feral, village, or community dogs, with pet dogs uncommon.[103][pageneeded] "The most widespread form of interspecies bonding occurs between humans and dogs"[104]and the keeping of dogs as companions, particularly by elites, has a long history.[14]Pet dog populations grew significantly afterWorld War IIas suburbanization increased.[14]In the 1950s and 1960s, dogs were kept outside more often than they tend to be today[105](the expression "in the doghouse" - recorded since 1932[106]- to describe exclusion from the group implies a distance between thedoghouseand the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the pet dog's role, such as the increased role of dogs in the emotional support of their human guardians.[107][pageneeded]People and their dogs have become increasingly integrated and implicated in each other's lives[108][pageneeded]to the point where pet dogs actively shape how a family and home are experienced.[109] There have been two significant trends occurring within the second half of the 20th century in pet dogs' changing status. The first has been"commodification", shaping it to conform to social expectations of personality and behavior.[109]The second has been the broadening of the family's concept and the home to include dogs-as-dogs within everyday routines and practices.[109] A vast range of commodity forms aims to transform a pet dog into an ideal companion.[110]The list of goods, services, and places available is enormous: from dog perfumes, couture, furniture and housing to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches and dog hotels, airlines and cemeteries.[110]Dog training books, classes, and television programs proliferated as the process of commodifying the pet dog continued.[111] The majority of contemporary dog owners describe their pet as part of the family, although some ambivalence about the relationship is evident in the popular reconceptualization of the dog-human family as a pack.[109]Some dog trainers, such as on the television programDog Whisperer, have promoted adominance modelof dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions.[112]The idea of the "alpha dog" trying to be dominant is based on a disproved theory about wolf packs.[113][114]Pet dogs play an active role in family life; for example, a study of conversations in dog-human families showed how family members use the dog as a resource, talking to the dog, or talking through the dog; to mediate their interactions with each other.[115] Increasingly, human family-members engage in activities centered on the dog's perceived needs and interests, or in which the dog is an integral partner, such asdog dancinganddog yoga.[110] According to statistics published by theAmerican Pet Products Manufacturers Associationin the National Pet Owner Survey in 2009–2010, an estimated 77.5million people in the United States have pet dogs.[116]The same source shows that nearly 40% of American households own at least one dog, of which 67% own just one dog, 25% two dogs and nearly 9% more than two dogs. There does not seem to be anygender preferenceamong dogs as pets, as the statistical data reveal an equal number of male and female pet dogs. Although several programs promotepet adoption, less than one-fifth of the owned dogs come fromshelters.[116] A study usingmagnetic resonance imaging(MRI) to compare humans and dogs showed that dogs have the same response to voices and use the same parts of the brain as humans do. This gives dogs the ability to recognize human emotional sounds, making them friendly social pets to humans.[117] Workers Dogs have lived and worked with humans in many roles. In addition to dogs' role as companion animals, dogs have been bred for herding livestock (collies,sheepdogs),[118][pageneeded][12]hunting (hounds, pointers)[119][pageneeded]and rodent control (terriers).[12]Other types ofworking dogsincludesearch and rescue dogs,[120]detection dogstrained to detectillicit drugs[121]orchemical weapons;[122]guard dogs; dogs who assist fishermen with the use of nets; and dogs that pull loads.[12]In 1957, the dogLaikabecame the first animal to be launched intoEarth orbit, aboard theSoviets'Sputnik 2; she died during the flight.[123][124] Various kinds ofservice dogsandassistance dogs, includingguide dogs,hearing dogs,mobility assistance dogsandpsychiatric service dogs, assist individuals with disabilities.[125][126]Some dogs owned by people with epilepsy have been shown to alert their handler when the handler shows signs of an impending seizure, sometimes well in advance of onset, allowing the guardian to seek safety, medication, or medical care.[127] Athletes and models See also:Conformation show People often enter their dogs in competitions, such as breed-conformation shows orsports, including racing, sledding and agility competitions. In conformation shows, also referred to as breed shows, a judge familiar with the specific dog breed evaluates individual purebred dogs for conformity with their established breed type as described in the breed standard. As the breed standard only deals with the dog's externally observable qualities (such as appearance, movement and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows. Food Main article:Dog meat Dog meat is consumed in someEast Asiancountries, includingKorea,[128][pageneeded]China,[101]Vietnam[102]and thePhilippines,[129]which dates back to antiquity.[130]Based on limited data, it is estimated that 13–16million dogs are killed and consumed in Asia every year.[131]In China, debates have ensued over banning the consumption of dog meat.[132]Following the Sui and Tang dynasties of the first millennium, however, people living on northern China's plains began to eschew eating dogs, which is likely due to Buddhism and Islam's spread, two religions that forbade the consumption of certain animals, including the dog. As members of the upper classes shunned dog meat, it gradually became a social taboo to eat it, even though the general population continued to consume it for centuries afterward.[133]Dog meat is also consumed in some parts of Switzerland.[134]Other cultures, such asPolynesiaandpre-Columbian Mexico, also consumed dog meat in their history. Dog fat is also reportedly believed to be beneficial for the lungs in some parts of Poland[135][136]and Central Asia.[137][138]Proponents of eating dog meat have argued that placing a distinction between livestock and dogs is Western hypocrisy and that there is no difference in eating different animals' meat.[139][140][141][142] In Korea, the primary dog breed raised for meat, theNureongi, differs from those breeds raised for pets that Koreans may keep in their homes.[143] The most popular Korean dog dish is calledbosintang, a spicy stew meant to balance the body's heat during the summer months. Followers of the custom claim this is done to ensure good health by balancing one'sgi, or the body's vital energy. A 19th-century version of bosintang explains that the dish is prepared by boiling dog meat withscallionsand chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still prevalent in Korea with a segment of the population, dog is not as widely consumed as beef, pork and chicken.[143] Health risks Further information:Dog bite,Canine vector-borne disease, andDog bite prevention In 2018, theWHOreported that 59,000 people died globally fromrabies, with 59.6% in Asia and 36.4% in Africa. Rabies is a disease for which dogs are the most important vector.[144]Significant dog bites affect tens of millions of people globally each year. Children in mid-to-late childhood are the largest percentage bitten by dogs, with a greater risk of injury to the head and neck. They are more likely to need medical treatment and have the highest death rate.[145]Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.[146] In theU.S.,catsand dogs are a factor in more than 86,000 falls each year.[147]It has been estimated that around 2% of dog-related injuries treated in U.K. hospitals are domestic accidents. The same study found that while dog involvement in road traffic accidents was difficult to quantify, dog-associated road accidents involving injury more commonly involved two-wheeled vehicles.[148] Toxocara canis(dogroundworm) eggs in dog feces can causetoxocariasis. In the United States, about 10,000 cases ofToxocarainfection are reported in humans each year, and almost 14% of the U.S. population is infected.[149]Untreated toxocariasis can cause retinal damage and decreased vision.[150]Dog feces can also containhookwormsthat causecutaneous larva migransin humans.[151][152] Health benefits  Walking a dog Dogs suffer from the same common disorders as humans; these include cancer, diabetes, heart disease and neurologic disorders. Their pathology is similar to humans, as is their response to treatment and their outcomes. Researchers are identifying the genes associated with dog diseases similar to human disorders, but lack mouse models to find cures for both dogs and humans. The genes involved in canine obsessive-compulsive disorders led to the detection of four genes in humans' related pathways.[10] The scientific evidence is mixed as to whether a dog's companionship can enhance human physical health and psychological well-being.[153]Studies suggesting that there are benefits to physical health and psychological well-being[154]have been criticized for being poorly controlled.[155]It found that "the health of elderly people is related to their health habits and social supports but not to their ownership of, or attachment to, a companion animal." Earlier studies have shown that people who keep pet dogs or cats exhibit better mental and physical health than those who do not, making fewer visits to the doctor and being less likely to be on medication than non-guardians.[156] A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."[153]In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition. This effect was sustained in those with dogs through to the end of the study.[157] People with pet dogs took considerably more physical exercise than those with cats and those without pets. The results provide evidence that keeping pets may have positive effects on human health and behavior and that for guardians of dogs, these effects are relatively long-term.[157]Pet guardianship has also been associated with increased coronary artery disease survival. Human guardians are significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs.[158]The association between dog ownership and adult physical activity levels has been reviewed by several authors.[159][160] The health benefits of dogs can result from contact with dogs in general, not solely from having dogs as pets. For example, when in a pet dog's presence, people show reductions in cardiovascular, behavioral and psychological indicators of anxiety.[161]Other health benefits are gained from exposure to immune-stimulating microorganisms, which can protect against allergies and autoimmune diseases according to thehygiene hypothesis. The benefits of contact with a dog also include social support, as dogs cannot only provide companionship and social support themselves but also act as facilitators of social interactions between humans.[162]One study indicated that wheelchair users experience more positive social interactions with strangers when accompanied by a dog than when they are not.[163]In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners.[164] Using dogs and other animals as a part of therapy dates back to the late 18th century, when animals were introduced into mental institutions to help socialize patients with mental disorders.[165]Animal-assisted intervention research has shown that animal-assisted therapy with a dog can increase social behaviors, such as smiling and laughing, among people with Alzheimer's disease.[166]One study demonstrated that children with ADHD and conduct disorders who participated in an education program with dogs and other animals showed increased attendance, increased knowledge and skill objectives and decreased antisocial and violent behavior compared with those not in an animal-assisted program.[167] Cultural importance Main articles:Cultural depictions of dogsandDogs in religion Further information:List of fictional dogs  Cerberus, with the gluttons inDante'sThird Circle of Hell.William Blake. Dogs were depicted to symbolizeguidance,protection,loyalty,fidelity,faithfulness,alertness, andlove.[168]In ancientMesopotamia, from theOld Babylonian perioduntil theNeo-Babylonian, dogs were the symbol ofNinisina, the goddess of healing and medicine,[169]and her worshippers frequently dedicated small models of seated dogs to her.[169]In theNeo-Assyrianand Neo-Babylonian periods, dogs were used as emblems of magical protection.[169]InChina,KoreaandJapan, dogs are viewed as kind protectors.[170] In mythology, dogs often serve as pets or as watchdogs.[170]Stories of dogs guarding the gates of the underworld recur throughout Indo-European mythologies[171][172]and may originate fromProto-Indo-European religion.[171][172]InGreek mythology,Cerberusis a three-headed,dragon-tailed watchdog who guards the gates ofHades.[170]Dogs are also associated with the Greek goddessHecate.[173]InNorse mythology, a bloody, four-eyed dog calledGarmrguardsHelheim.[170]InPersian mythology, two four-eyed dogs guard theChinvat Bridge.[170]InWelsh mythology,Annwnis guarded byCŵn Annwn.[170]InHindu mythology,Yama, the god of death, owns two watchdogs who have four eyes. They are said to watch over the gates ofNaraka.[174]A black dog is also considered to be thevahana(vehicle) ofBhairava(an incarnation of Shiva).[175] InChristianity, dogs represent faithfulness.[170]Within theRoman Catholicdenomination specifically, the iconography ofSaint Dominicincludes a dog, after the hallow's mother dreamt of a dog springing from her womb and becoming pregnant shortly after that.[176]As such, theDominican Order(Ecclesiastical Latin:Domini canis) means "dog of the Lord" or "hound of the Lord" (Ecclesiastical Latin:Domini canis).[176]In Christian folklore, achurch grimoften takes the form of a black dog to guard Christian churches and theirchurchyardsfromsacrilege.[177]Jewish lawdoes not prohibit keeping dogs and other pets.[178]Jewish law requires Jews to feed dogs (and other animals that they own) before themselves and make arrangements for feeding them before obtaining them.[178]The view on dogs inIslamis mixed, with some schools of thought viewing it as unclean,[170]althoughKhaled Abou El Fadlstates that this view is based on "pre-Islamic Arab mythology" and "a tradition to be falsely attributed to the Prophet."[179]Therefore, Sunni Malaki and Hanafi jurists permit the trade of and keeping of dogs as pets.[180]

In 1758, the Swedish botanist and zoologistCarl Linnaeuspublished in hisSystema Naturae, the two-word naming of species (binomial nomenclature).Canisis theLatinword meaning "dog",[15]and under thisgenus, he listed the domestic dog, thewolf, and thegolden jackal. He classified the domestic dog asCanis familiarisand, on the next page, classified the grey wolf asCanis lupus.[2]Linnaeus considered the dog to be a separate species from the wolf because of its upturning tail (cauda recurvata), which is not found in any othercanid.[16] In 1999, a study ofmitochondrial DNA(mtDNA) indicated that the domestic dog may have originated from the grey wolf, with thedingoandNew Guinea singing dogbreeds having developed at a time when human communities were more isolated from each other.[17]In the third edition ofMammal Species of the Worldpublished in 2005, themammalogistW. Christopher Wozencraftlisted under the wolfCanis lupusits wild subspecies and proposed two additional subspecies, which formed the domestic dog clade:familiaris, as named by Linnaeus in 1758 and,dingonamed by Meyer in 1793. Wozencraft includedhallstromi(the New Guinea singing dog) as another name (junior synonym) for the dingo. Wozencraft referred to the mtDNA study as one of the guides informing his decision.[3]Mammalogists have noted the inclusion offamiliarisanddingotogether under the "domestic dog" clade[18]with some debating it.[19] In 2019, a workshop hosted by theIUCN/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to beferalCanis familiarisand therefore did not assess them for theIUCN Red List of Threatened Species.[4] Evolution Main article:Evolution of the wolf  Location of a dog'scarnassials; the inside of the 4th upperpremolaraligns with the outside of the 1st lowermolar, working like scissor blades TheCretaceous–Paleogene extinction eventoccurred 65 million years ago and brought an end to the dinosaurs and the appearance of the first carnivorans.[20]The namecarnivoranis given to a member of the orderCarnivora. Carnivorans possess a common arrangement of teeth calledcarnassials, in which the first lowermolarand the last upperpremolarpossess blade-like enamelcrownsthat act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether as in seals, sea lions, and walruses. Today, not all carnivorans arecarnivores, such as the insect-eatingAardwolf.[5] The carnivoran ancestors of the dog-likecaniformsand the cat-likefeliformsbegan their separate evolutionary paths just after the end of the dinosaurs. The first members of the dog familyCanidaeappeared 40 million years ago,[21]of which only its subfamily theCaninaesurvives today in the form of the wolf-like and fox-like canines. Within the Caninae, the first members of genusCanisappeared six million years ago,[15]the ancestors of modern domestic dogs, wolves,coyotes, and golden jackals. Domestication Main article:Domestication of the dog The earliest remains generally accepted to be those of a domesticated dog were discovered inBonn-Oberkassel, Germany. Contextual, isotopic, genetic, and morphological evidence shows that this dog was not a local wolf.[22]The dog was dated to 14,223 years ago and was found buried along with a man and a woman, all three having been sprayed with redhematitepowder and buried under large, thick basalt blocks. The dog had died ofcanine distemper.[23]Earlier remains dating back to 30,000 years ago have been described asPaleolithic dogs, but their status as dogs or wolves remains debated[24]because considerablemorphologicaldiversity existed among wolves during theLate Pleistocene.[1] This timing indicates that the dog was the first species to be domesticated[9][8]in the time ofhunter–gatherers,[7]which predates agriculture.[1]DNA sequencesshow that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from themodern wolflineage.[6][7]Most dogs form a sister group to the remains of a LatePleistocene wolffound in theKessleroch cavenearThayngenin the canton ofSchaffhausen,Switzerland, which dates to 14,500 years ago. Themost recent common ancestorof both is estimated to be from 32,100 years ago.[25]This indicates that an extinct Late Pleistocene wolf may have been the ancestor of the dog,[8][1][26]with the modern wolf being the dog's nearest living relative.[8] The dog is a classic example of a domestic animal that likely travelled acommensalpathway into domestication.[24][27]The questions of when and where dogs were first domesticated have taxed geneticists and archaeologists for decades.[9]Genetic studies suggest a domestication process commencing over 25,000 years ago, in one or several wolf populations in either Europe, the high Arctic, or eastern Asia.[10]In 2021, aliterature reviewof the current evidenceinfersthat the dog was domesticated inSiberia23,000 years ago byancient North Siberians, then later dispersed eastward into the Americas and westward across Eurasia.[22] Breeds Main article:Dog breed Further information:Dog type  Dog breeds show a range ofphenotypic variation Dogs are the most variable mammal on earth with around 450 globally recognizeddog breeds.[10]In theVictorian era, directed humanselectiondeveloped the moderndog breeds, which resulted in a vast range of phenotypes.[8]Most breeds were derived from small numbers of founders within the last 200 years,[8][10]and since then dogs have undergone rapidphenotypicchange and were formed into today's modern breeds due toartificial selectionimposed by humans. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour.[8]Their behavioural traits include guarding, herding, and hunting,[8]retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression,[10]which demonstrates the functional and behavioral diversity of dogs.[8]As a result, present day dogs are the most abundant carnivore species and are dispersed around the world.[10]The most striking example of this dispersal is that of the numerous modern breeds of European lineage during theVictorian era.[7] Biology Anatomy Main article:Dog anatomy Skeleton  A lateral view of a dog skeleton All healthy dogs, regardless of their size and type, have an identicalskeletalstructure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types.[28][29]The dog's skeleton is well adapted for running; thevertebraeon the neck and back have extensions for powerful back muscles to connect to, the long ribs provide plenty of room for the heart and lungs, and the shoulders are unattached to the skeleton allowing great flexibility.[28][29] Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog's skeleton greatly enhanced in size for larger types asmastiffsand miniaturised for smaller types such asterriers;dwarfismhas been selectively utilised for some types where short legs are advantageous such asdachshundsandcorgis.[29]Most dogs naturally have 26 vertebrae in their tails, but some withnaturally short tailshave as few as three.[28] The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types.[29][30]The three basic skull shapes are the elongated dolichocephalic type as seen insighthounds, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls.[29][30] Senses Further information:Dog anatomy §Senses A dog's senses include vision, hearing, smell, taste, touch, and sensitivity to Earth's magnetic field. Another study has suggested that dogs can see Earth's magnetic field.[31] Coat Main article:Dog coat  Dogs display wide variation in coat type, density, length, color, and composition Thecoatsof domestic dogs are of two varieties: "double" being familiar with dogs (as well as wolves) originating from colder climates, made up of a coarseguard hairand a softdown hair, or "single", with the topcoat only. Breeds may have an occasional "blaze", stripe, or "star" of white fur on their chest or underside.[32]Premature graying can occur in dogs from as early as one year of age; this is associated withimpulsive behaviors,anxiety behaviors, fear of noise, and fear of unfamiliar people or animals.[33] Tail There are many different shapes fordog tails: straight, straight up, sickle, curled, or corkscrew. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be crucial in getting along with others. In some hunting dogs the tail is traditionallydockedto avoid injuries. Health Main article:Dog health Some breeds of dogs are prone to specific genetic ailments such aselbowandhip dysplasia,blindness,deafness,pulmonic stenosis,cleft palate, andtrick knees. Two severe medical conditions significantly affecting dogs arepyometra, affectingunspayedfemales of all breeds and ages, andGastric dilatation volvulus(bloat), which affects larger breeds or deep-chested dogs. Both of these are acute conditions and can kill rapidly. Dogs are also susceptible to parasites such asfleas,ticks,mites,hookworms,tapeworms,roundworms, andheartworms, which is aroundwormspecies that lives in the hearts of dogs. Several human foods and household ingestibles are toxic to dogs, includingchocolate solids, causingtheobromine poisoning,onionsandgarlic, causingthiosulphate,sulfoxideordisulfidepoisoning,grapesandraisins,macadamia nuts, andxylitol.[34]The nicotine in tobacco can also be dangerous to dogs. Signs of ingestion can include copious vomiting (e.g., from eating cigar butts) ordiarrhea. Some other symptoms are abdominal pain, loss of coordination, collapse, or death.[35][pageneeded] Dogs are also vulnerable to some of the same health conditions as humans, includingdiabetes,dentalandheart disease,epilepsy,cancer,hypothyroidism, andarthritis. Lifespan Further information:Aging in dogs The typical lifespan of dogs varies widely among breeds, but for most, the median longevity (the age at which half the dogs in a population have died and half are still alive) ranges from 10 to 13 years.[36][37]The median longevity ofmixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[36][37][38]For dogs in England, increased body weight has been found to be negatively correlated with longevity (i.e., the heavier the dog, the shorter its lifespan), andmixed-breed dogslive on average 1.2 years longer thanpurebred dogs.[39] Reproduction Main article:Canine reproduction  A female dog nursing newborn puppies. In domestic dogs,sexual maturityhappens around six months to one year for both males and females, although this can be delayed until up to two years of age for some large breeds, and is the time at which female dogs will have their firstestrous cycle. They will experience subsequent estrous cycles semiannually, during which the body prepares forpregnancy. At the peak of the cycle, females will become estrous, mentally and physically receptive tocopulation. Because theovasurvive and can be fertilized for a week after ovulation, more than one male can sire the same litter.[12] Fertilization typically occurs two to five days after ovulation; 14–16 days after ovulation, the embryo attaches to the uterus and after seven to eight more days, a heartbeat is detectable.[40][41] Dogs bear their litters roughly 58 to 68 days afterfertilization,[12][42]with an average of 63 days, although the length of gestation can vary. An average litter consists of about sixpuppies.[43] Neutering Neuteringrefers to the sterilization of animals, usually byremoving the male's testiclesor the female'sovariesanduterus, to eliminate the ability to procreate and reducesex drive. Because ofdogs' overpopulationin some countries, many animal control agencies, such as theAmerican Society for the Prevention of Cruelty to Animals(ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized.[44] According to theHumane Society of the United States, three to four million dogs and cats areeuthanizedeach year.[45]Many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down.[46] Neutering reduces problems caused byhypersexuality, especially in male dogs.[47]Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs.[48][pageneeded]However, neutering increases the risk ofurinary incontinencein female dogs[49]andprostate cancerin males[50]andosteosarcoma,hemangiosarcoma,cruciate ligamentrupture, obesity, anddiabetes mellitusin either sex.[51] Inbreeding depression A common breeding practice for pet dogs is mating between close relatives (e.g., between half and full siblings).[52]Inbreeding depressionis considered to be due mainly to the expression of homozygous deleterious recessive mutations.[53]Outcrossing between unrelated individuals, including dogs of different breeds, results in the beneficial masking of deleterious recessive mutations in progeny.[54] In a study of seven dog breeds (theBernese Mountain Dog,Basset Hound,Cairn Terrier,Brittany,German Shepherd Dog,Leonberger, andWest Highland White Terrier), it was found that inbreeding decreases litter size and survival.[55]Another analysis of data on 42,855Dachshundlitters found that as theinbreeding coefficientincreased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression.[56]In a study ofBoxerlitters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.[57] Behavior Main article:Dog behavior See also:Dog behavior §Behavior compared with other canids Dog behavior is the internally coordinated responses (actions or inactions) of the domestic dog (individuals or groups) to internal and external stimuli.[58]As the oldest domesticated species, dogs' minds inevitably have been shaped by millennia of contact with humans. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans more than any other species and they are uniquely attuned to human behaviors.[13]Behavioral scientists have uncovered a surprising set of social-cognitive abilities in domestic dogs. These abilities are not possessed by the dog's closest canine relatives or other highly intelligent mammals, such asgreat apes, but rather parallel to children's social-cognitive skills.[59] Unlike other domestic species selected for production-related traits, dogs were initially selected for their behaviors.[60][61]In 2016, a study found that only 11 fixed genes showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect thecatecholamine synthesispathway, with the majority of the genes affecting the fight-or-flight response[61][62](i.e., selection for tameness) and emotional processing.[61]Dogs generally show reduced fear and aggression compared with wolves.[61][63]Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and later in breed formation.[61]Traits of high sociability and lack of fear in dogs may include genetic modifications related toWilliams-Beuren syndromein humans, which causehypersociabilityat the expense of problem-solving ability.[64] Intelligence Main article:Dog intelligence Dog intelligence is the dog's ability to perceive information and retain it as knowledge for applying to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills. A study withRico, aBorder Collie, showed that he knew the labels of over 200 different items. He inferred the names of novel things by exclusion learning and correctly retrieved those new items immediately and four weeks after the initial exposure. A study of another Border Collie, Chaser, documented his learning and memory capabilities. He had learned the names and could associate by verbal command over 1,000 words.[65]Dogs can read and react appropriately to human body language such as gesturing and pointing and human voice commands. One study of canine cognitive abilities found that dogs' capabilities are no more exceptional than those of other animals, such ashorses,chimpanzees, orcats.[66]One limited study of 18 household dogs found that they lacked spatial memory, and were more focussed on the "what" of a task rather than the "where".[67] Dogs demonstrate atheory of mindby engaging in deception.[68]An experimental study showed compelling evidence that Australiandingoscan outperform domestic dogs in non-social problem-solving, indicating that domestic dogs may have lost much of their original problem-solving abilities once they joined humans.[69]Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an unsolvable version of the same problem look at the human, while socialized wolves do not.[70] Communication Main article:Dog communication  Dog sounds 0:15 A dog making noises and barking Problems playing this file? Seemedia help. Dog communication is how dogs convey information to other dogs, understand messages from humans and translate the information that dogs are transmitting.[71]: xii Communication behaviors of dogs include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs), and gustatory communication (scents, pheromones, and taste). Humans communicate to dogs by using vocalization, hand signals, and body posture. Ecology Population The dog is probably the most widely abundant largecarnivoranliving in the human environment.[72][73]In 2013, the estimated global dog population was between 700 million[74]and 987 million.[75]About 20% of dogs live as pets in developed countries.[76]In the developing world, dogs are more commonly feral or communally owned, with pet dogs uncommon. Most of these dogs live their lives as scavengers and have never been owned by humans, with one study showing their most common response when approached by strangers is to run away (52%) or respond aggressively (11%).[77]Little is known about these dogs, or the dogs in developed countries that are feral, strays, or are in shelters because the great majority of modern research on dog cognition has focused on pet dogs living in human homes.[78] Competitors and predators Although dogs are the most abundant and widely distributed terrestrial carnivores, feral andfree-ranging dogs' potentialto compete with other large carnivores is limited by their strong association with humans.[72]For example, a review of the studies in dogs' competitive effects onsympatriccarnivores did not mention any research on competition between dogs and wolves.[79][80]Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups.[79][81] Wolves kill dogs wherever they are found together.[82]In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs to the extent that they have to be beaten off or killed.[83]Although the numbers of dogs killed each year are relatively low, it induces a fear of wolves entering villages and farmyards to take dogs and losses of dogs to wolves have led to demands for more liberal wolf hunting regulations.[79] Coyotesandbig catshave also been known to attack dogs. In particular,leopardsare known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size.[84]Siberian tigersin theAmur Riverregion have killed dogs in the middle of villages. This indicates that the dogs were targeted. Amur tigers will not tolerate wolves as competitors within their territories, and the tigers could be considering dogs in the same way.[85]Striped hyenasare known to kill dogs in their range.[86] Diet See also:Dog food  AGolden Retrievergnawing on a pig's foot Dogs have been described asomnivores.[12][87][88]Compared to wolves, dogs from agricultural societies haveextra copies of amylaseand other genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet.[11]Similar to humans, some dog breeds produce amylase in theirsalivaand are classified as having a high starch diet.[89]However, more like cats and less like other omnivores, dogs can only producebile acidwithtaurineand they cannot producevitamin D, which they obtain from animal flesh. Also more like cats, dogs requirearginineto maintain its nitrogen balance. These nutritional requirements place dogs halfway between carnivores and omnivores.[90] Range As a domesticated or semi-domesticated animal, the dog is nearly universal among human societies. Notable exceptions once included: TheAboriginal Tasmanians, who were separated from Australia before the arrival ofdingoson that continent TheAndamanese peoples, who were isolated whenrising sea levelscovered the land bridge to Myanmar TheFuegians, who instead domesticated theFuegian dog, a different canid species Individual Pacific islands whose maritime settlers did not bring dogs, or where dogs died out after original settlement, notably theMariana Islands,[91]Palau[92]and most of theCaroline Islandswith exceptions such asFais IslandandNukuoro,[93]theMarshall Islands,[94]theGilbert Islands,[94]New Caledonia,[95]Vanuatu,[95][96]Tonga,[96]Marquesas,[96]Mangaiain theCook Islands,Rapa ItiinFrench Polynesia,Easter Island,[96]theChatham Islands[97]andPitcairn Island(settled by theBountymutineers, who killed off their dogs to escape discovery by passing ships).[98] Dogs were introduced toAntarcticaassled dogs, but were later outlawed by international agreement due to the possible risk of spreading infections.[99] Roles with humans Domestic dogs inherited complex behaviors, such asbite inhibition, from their wolf ancestors, which would have beenpack hunterswith a complex body language. These sophisticated forms of social cognition and communication may account for their trainability, playfulness and ability to fit into human households and social situations. These attributes have given dogs a relationship with humans that has enabled them to become one of the most successful animals today.[100] The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such ashunting,herding,pulling loads,protection,assisting policeand themilitary,companionshipandaiding disabled individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogsare also a source of meat.[101][102] Pets  Siberian Huskiesarepack animalsthat still enjoy some human companionship It is estimated that three-quarters of the world's dog population lives in the developing world as feral, village, or community dogs, with pet dogs uncommon.[103][pageneeded] "The most widespread form of interspecies bonding occurs between humans and dogs"[104]and the keeping of dogs as companions, particularly by elites, has a long history.[14]Pet dog populations grew significantly afterWorld War IIas suburbanization increased.[14]In the 1950s and 1960s, dogs were kept outside more often than they tend to be today[105](the expression "in the doghouse" - recorded since 1932[106]- to describe exclusion from the group implies a distance between thedoghouseand the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the pet dog's role, such as the increased role of dogs in the emotional support of their human guardians.[107][pageneeded]People and their dogs have become increasingly integrated and implicated in each other's lives[108][pageneeded]to the point where pet dogs actively shape how a family and home are experienced.[109] There have been two significant trends occurring within the second half of the 20th century in pet dogs' changing status. The first has been"commodification", shaping it to conform to social expectations of personality and behavior.[109]The second has been the broadening of the family's concept and the home to include dogs-as-dogs within everyday routines and practices.[109] A vast range of commodity forms aims to transform a pet dog into an ideal companion.[110]The list of goods, services, and places available is enormous: from dog perfumes, couture, furniture and housing to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches and dog hotels, airlines and cemeteries.[110]Dog training books, classes, and television programs proliferated as the process of commodifying the pet dog continued.[111] The majority of contemporary dog owners describe their pet as part of the family, although some ambivalence about the relationship is evident in the popular reconceptualization of the dog-human family as a pack.[109]Some dog trainers, such as on the television programDog Whisperer, have promoted adominance modelof dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions.[112]The idea of the "alpha dog" trying to be dominant is based on a disproved theory about wolf packs.[113][114]Pet dogs play an active role in family life; for example, a study of conversations in dog-human families showed how family members use the dog as a resource, talking to the dog, or talking through the dog; to mediate their interactions with each other.[115] Increasingly, human family-members engage in activities centered on the dog's perceived needs and interests, or in which the dog is an integral partner, such asdog dancinganddog yoga.[110] According to statistics published by theAmerican Pet Products Manufacturers Associationin the National Pet Owner Survey in 2009–2010, an estimated 77.5million people in the United States have pet dogs.[116]The same source shows that nearly 40% of American households own at least one dog, of which 67% own just one dog, 25% two dogs and nearly 9% more than two dogs. There does not seem to be anygender preferenceamong dogs as pets, as the statistical data reveal an equal number of male and female pet dogs. Although several programs promotepet adoption, less than one-fifth of the owned dogs come fromshelters.[116] A study usingmagnetic resonance imaging(MRI) to compare humans and dogs showed that dogs have the same response to voices and use the same parts of the brain as humans do. This gives dogs the ability to recognize human emotional sounds, making them friendly social pets to humans.[117] Workers Dogs have lived and worked with humans in many roles. In addition to dogs' role as companion animals, dogs have been bred for herding livestock (collies,sheepdogs),[118][pageneeded][12]hunting (hounds, pointers)[119][pageneeded]and rodent control (terriers).[12]Other types ofworking dogsincludesearch and rescue dogs,[120]detection dogstrained to detectillicit drugs[121]orchemical weapons;[122]guard dogs; dogs who assist fishermen with the use of nets; and dogs that pull loads.[12]In 1957, the dogLaikabecame the first animal to be launched intoEarth orbit, aboard theSoviets'Sputnik 2; she died during the flight.[123][124] Various kinds ofservice dogsandassistance dogs, includingguide dogs,hearing dogs,mobility assistance dogsandpsychiatric service dogs, assist individuals with disabilities.[125][126]Some dogs owned by people with epilepsy have been shown to alert their handler when the handler shows signs of an impending seizure, sometimes well in advance of onset, allowing the guardian to seek safety, medication, or medical care.[127] Athletes and models See also:Conformation show People often enter their dogs in competitions, such as breed-conformation shows orsports, including racing, sledding and agility competitions. In conformation shows, also referred to as breed shows, a judge familiar with the specific dog breed evaluates individual purebred dogs for conformity with their established breed type as described in the breed standard. As the breed standard only deals with the dog's externally observable qualities (such as appearance, movement and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows. Food Main article:Dog meat Dog meat is consumed in someEast Asiancountries, includingKorea,[128][pageneeded]China,[101]Vietnam[102]and thePhilippines,[129]which dates back to antiquity.[130]Based on limited data, it is estimated that 13–16million dogs are killed and consumed in Asia every year.[131]In China, debates have ensued over banning the consumption of dog meat.[132]Following the Sui and Tang dynasties of the first millennium, however, people living on northern China's plains began to eschew eating dogs, which is likely due to Buddhism and Islam's spread, two religions that forbade the consumption of certain animals, including the dog. As members of the upper classes shunned dog meat, it gradually became a social taboo to eat it, even though the general population continued to consume it for centuries afterward.[133]Dog meat is also consumed in some parts of Switzerland.[134]Other cultures, such asPolynesiaandpre-Columbian Mexico, also consumed dog meat in their history. Dog fat is also reportedly believed to be beneficial for the lungs in some parts of Poland[135][136]and Central Asia.[137][138]Proponents of eating dog meat have argued that placing a distinction between livestock and dogs is Western hypocrisy and that there is no difference in eating different animals' meat.[139][140][141][142] In Korea, the primary dog breed raised for meat, theNureongi, differs from those breeds raised for pets that Koreans may keep in their homes.[143] The most popular Korean dog dish is calledbosintang, a spicy stew meant to balance the body's heat during the summer months. Followers of the custom claim this is done to ensure good health by balancing one'sgi, or the body's vital energy. A 19th-century version of bosintang explains that the dish is prepared by boiling dog meat withscallionsand chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still prevalent in Korea with a segment of the population, dog is not as widely consumed as beef, pork and chicken.[143] Health risks Further information:Dog bite,Canine vector-borne disease, andDog bite prevention In 2018, theWHOreported that 59,000 people died globally fromrabies, with 59.6% in Asia and 36.4% in Africa. Rabies is a disease for which dogs are the most important vector.[144]Significant dog bites affect tens of millions of people globally each year. Children in mid-to-late childhood are the largest percentage bitten by dogs, with a greater risk of injury to the head and neck. They are more likely to need medical treatment and have the highest death rate.[145]Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.[146] In theU.S.,catsand dogs are a factor in more than 86,000 falls each year.[147]It has been estimated that around 2% of dog-related injuries treated in U.K. hospitals are domestic accidents. The same study found that while dog involvement in road traffic accidents was difficult to quantify, dog-associated road accidents involving injury more commonly involved two-wheeled vehicles.[148] Toxocara canis(dogroundworm) eggs in dog feces can causetoxocariasis. In the United States, about 10,000 cases ofToxocarainfection are reported in humans each year, and almost 14% of the U.S. population is infected.[149]Untreated toxocariasis can cause retinal damage and decreased vision.[150]Dog feces can also containhookwormsthat causecutaneous larva migransin humans.[151][152] Health benefits  Walking a dog Dogs suffer from the same common disorders as humans; these include cancer, diabetes, heart disease and neurologic disorders. Their pathology is similar to humans, as is their response to treatment and their outcomes. Researchers are identifying the genes associated with dog diseases similar to human disorders, but lack mouse models to find cures for both dogs and humans. The genes involved in canine obsessive-compulsive disorders led to the detection of four genes in humans' related pathways.[10] The scientific evidence is mixed as to whether a dog's companionship can enhance human physical health and psychological well-being.[153]Studies suggesting that there are benefits to physical health and psychological well-being[154]have been criticized for being poorly controlled.[155]It found that "the health of elderly people is related to their health habits and social supports but not to their ownership of, or attachment to, a companion animal." Earlier studies have shown that people who keep pet dogs or cats exhibit better mental and physical health than those who do not, making fewer visits to the doctor and being less likely to be on medication than non-guardians.[156] A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."[153]In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition. This effect was sustained in those with dogs through to the end of the study.[157] People with pet dogs took considerably more physical exercise than those with cats and those without pets. The results provide evidence that keeping pets may have positive effects on human health and behavior and that for guardians of dogs, these effects are relatively long-term.[157]Pet guardianship has also been associated with increased coronary artery disease survival. Human guardians are significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs.[158]The association between dog ownership and adult physical activity levels has been reviewed by several authors.[159][160] The health benefits of dogs can result from contact with dogs in general, not solely from having dogs as pets. For example, when in a pet dog's presence, people show reductions in cardiovascular, behavioral and psychological indicators of anxiety.[161]Other health benefits are gained from exposure to immune-stimulating microorganisms, which can protect against allergies and autoimmune diseases according to thehygiene hypothesis. The benefits of contact with a dog also include social support, as dogs cannot only provide companionship and social support themselves but also act as facilitators of social interactions between humans.[162]One study indicated that wheelchair users experience more positive social interactions with strangers when accompanied by a dog than when they are not.[163]In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners.[164] Using dogs and other animals as a part of therapy dates back to the late 18th century, when animals were introduced into mental institutions to help socialize patients with mental disorders.[165]Animal-assisted intervention research has shown that animal-assisted therapy with a dog can increase social behaviors, such as smiling and laughing, among people with Alzheimer's disease.[166]One study demonstrated that children with ADHD and conduct disorders who participated in an education program with dogs and other animals showed increased attendance, increased knowledge and skill objectives and decreased antisocial and violent behavior compared with those not in an animal-assisted program.[167] Cultural importance Main articles:Cultural depictions of dogsandDogs in religion Further information:List of fictional dogs  Cerberus, with the gluttons inDante'sThird Circle of Hell.William Blake. Dogs were depicted to symbolizeguidance,protection,loyalty,fidelity,faithfulness,alertness, andlove.[168]In ancientMesopotamia, from theOld Babylonian perioduntil theNeo-Babylonian, dogs were the symbol ofNinisina, the goddess of healing and medicine,[169]and her worshippers frequently dedicated small models of seated dogs to her.[169]In theNeo-Assyrianand Neo-Babylonian periods, dogs were used as emblems of magical protection.[169]InChina,KoreaandJapan, dogs are viewed as kind protectors.[170] In mythology, dogs often serve as pets or as watchdogs.[170]Stories of dogs guarding the gates of the underworld recur throughout Indo-European mythologies[171][172]and may originate fromProto-Indo-European religion.[171][172]InGreek mythology,Cerberusis a three-headed,dragon-tailed watchdog who guards the gates ofHades.[170]Dogs are also associated with the Greek goddessHecate.[173]InNorse mythology, a bloody, four-eyed dog calledGarmrguardsHelheim.[170]InPersian mythology, two four-eyed dogs guard theChinvat Bridge.[170]InWelsh mythology,Annwnis guarded byCŵn Annwn.[170]InHindu mythology,Yama, the god of death, owns two watchdogs who have four eyes. They are said to watch over the gates ofNaraka.[174]A black dog is also considered to be thevahana(vehicle) ofBhairava(an incarnation of Shiva).[175] InChristianity, dogs represent faithfulness.[170]Within theRoman Catholicdenomination specifically, the iconography ofSaint Dominicincludes a dog, after the hallow's mother dreamt of a dog springing from her womb and becoming pregnant shortly after that.[176]As such, theDominican Order(Ecclesiastical Latin:Domini canis) means "dog of the Lord" or "hound of the Lord" (Ecclesiastical Latin:Domini canis).[176]In Christian folklore, achurch grimoften takes the form of a black dog to guard Christian churches and theirchurchyardsfromsacrilege.[177]Jewish lawdoes not prohibit keeping dogs and other pets.[178]Jewish law requires Jews to feed dogs (and other animals that they own) before themselves and make arrangements for feeding them before obtaining them.[178]The view on dogs inIslamis mixed, with some schools of thought viewing it as unclean,[170]althoughKhaled Abou El Fadlstates that this view is based on "pre-Islamic Arab mythology" and "a tradition to be falsely attributed to the Prophet."[179]Therefore, Sunni Malaki and Hanafi jurists permit the trade of and keeping of dogs as pets.[180]

Crocodiles(familyCrocodylidae) ortrue crocodilesare largesemiaquaticreptilesthat live throughout the tropics inAfrica,Asia, theAmericasandAustralia. The term crocodile is sometimes used even more loosely to include allextantmembers of theorderCrocodilia, which includes thealligatorsandcaimans(familyAlligatoridae), thegharialandfalse gharial(familyGavialidae) among other extinct taxa. Crocodiles Temporal range:Eocene–Holocene,46–0Ma PreꞒ Ꞓ O S D C P T J K Pg N Nile crocodile(Crocodylus niloticus)Saltwater crocodile(Crocodylus porosus)Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:ReptiliaOrder:CrocodiliaSuperfamily:CrocodyloideaFamily:Crocodylidae Cuvier, 1807Type genusCrocodylus Laurenti, 1768 Subfamilies Crocodylinae Osteolaeminae Although they appear similar, crocodiles, alligators and the gharial belong to separate biologicalfamilies. The gharial, with its narrowsnout, is easier to distinguish, whilemorphologicaldifferences are more difficult to spot in crocodiles and alligators. The most obvious external differences are visible in the head, with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans. Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, and theteethin the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore, all teeth are visible, unlike an alligator, which possesses in the upper jaw small depressions into which the lower teeth fit. Also, when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define thespecies'family.[1]Crocodiles have morewebbingon the toes of the hindfeetand can better toleratesaltwaterdue to specializedsalt glandsfor filtering out salt, which are present, but non-functioning, in alligators. Another trait that separates crocodiles from other crocodilians is their much higher levels ofaggression.[2] Crocodilesize,morphology,behaviourandecologydiffer somewhat amongspecies. However, they have many similarities in these areas as well. All crocodiles aresemiaquaticand tend to congregate infreshwaterhabitats such asrivers,lakes,wetlandsand sometimes inbrackishwater andsaltwater. They arecarnivorousanimals, feeding mostly onvertebratessuch asfish,reptiles,birdsandmammals, and sometimes oninvertebratessuch asmolluscsandcrustaceans, depending on species and age. All crocodiles aretropicalspecies that, unlike alligators, are very sensitive tocold. They separated from othercrocodiliansduring theEoceneepoch, about 55 million years ago.[3]Many species are at the risk ofextinction, some being classified ascritically endangered. 1) Lions live in a group which is called as "pride"; 10 to 40 lions live in a pride. 2) In the group there are only 1 to 2 adult lions and others are lioness and their cubs. 3) Lions are very protective to themselves, their cubs and their area where they live. 4) Lions fight with other animals in order to protect their food as well as their group. 5) Male lions generally stay with their group and female lions do the hunting. 6) Approximately there are 10 sub-species of lions found in different parts of the world. 7) "South African Lion" or "Transvaal Lion" is considered as the largest sub-species of lions. 8) There are approximately 20000 to 39000 lions left in the world with 650 lions living in India. 9) Excessive hunting of lions has reduced their population worldwide which is posing a threat to ecosystem. 10) Lions are also kept in zoo for entertainment and recreation of the people.

Funny goat Thegoatordomestic goat(Capra hircus) is adomesticatedspecies ofgoat-antelopetypically kept aslivestock. It wasdomesticatedfrom thewild goat(C. aegagrus) ofSouthwest AsiaandEastern Europe. The goat is a member of the animal familyBovidaeand the tribeCaprini, meaning it is closely related to thesheep. There are over 300 distinctbreedsof goat.[1]It is one of the oldest domesticated species of animal, according to archaeological evidence that its earliest domestication occurred in Iran at 10,000 calibrated calendar years ago. Domestic goat Temporal range:0.01–0Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ Neolithic–Recent Apygmy goaton atree stump Conservation status Domesticated Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:ArtiodactylaFamily:BovidaeSubfamily:CaprinaeTribe:CapriniGenus:CapraSpecies: C.hircus Binomial nameCapra hircus Linnaeus,1758 Synonyms Capra aegagrus hircusLinnaeus,1758 Capra depressaLinnaeus,1758 Capra mambricaLinnaeus,1758 Capra reversaLinnaeus,1758 Goat-herding is an ancient tradition that is still important in places such as Egypt. Goats have been used formilk,meat,fur, andskinsacross much of the world.[3]Milk from goats is often turned intogoat cheese. Female goats are referred to asdoesornannies,intactmales are calledbucksorbillies, and juvenile goats of both sexes are calledkids.Castratedmales are calledwethers. While the wordshircineandcaprineboth refer to anything having a goat-like quality,hircineis used most often to emphasize the distinct smell of domestic goats. In 2011, there were more than 924 million goats living in the world, according to theUNFood and Agriculture Organization.

Heron attacked rat😲. The herons are medium- to large-sized birds with long legs and necks. They exhibit very littlesexual dimorphismin size. The smallest species is usually considered thedwarf bittern, which measures 25–30cm (10–12in) in length, although all the species in the genusIxobrychusare small and many broadly overlap in size. The largest species of heron is thegoliath heron, which stands up to 152cm (60in) tall. The necks are able to kink in an S-shape, due to the modified shape of the cervical vertebrae, of which they have 20–21. The neck can retract and extend and is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night herons and bitterns. The legs are long and strong and in almost every species are unfeathered from the lower part of thetibia(the exception is thezigzag heron). In flight, the legs and feet are held backwards. The feet of herons have long, thin toes, with three forward pointing ones and one pointing backwards. ThePacific reef heronhas twocolour morphs, the light and the dark. Thebillis generally long and harpoon-like. It can vary from extremely fine, as in theagami heron, to thick as in thegrey heron. The most atypical bill is owned by theboat-billed heron, which has a broad, thick bill. The bill and other bare parts of the body are usually yellow, black, or brown in colour, although this can vary during the breeding season. The wings are broad and long, exhibiting 10 or 11primary feathers(the boat-billed heron has only nine), 15–20 secondaries, and 12 rectrices (10 in the bitterns). The feathers of the herons are soft and theplumageis usually blue, black, brown, grey, or white, and can often be strikingly complex. Amongst the day herons, little sexual dimorphism in plumage is seen (except in the pond-herons); differences between the sexes are the rule for the night herons and smaller bitterns. Many species also have differentcolour morphs.In thePacific reef heron, both dark and light colour morphs exist, and the percentage of each morph varies geographically. White morphs only occur in areas with coral beaches.

The power of chicks never underestimate.

Stuck in tree hole a beby raccoon. The raccoon (/rəˈkuːn/ or US: /ræˈkuːn/ (listen), Procyon lotor), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of 40 to 70 cm (16 to 28 in), and a body weight of 5 to 26 kg (11 to 57 lb). Its grayish coat mostly consists of dense underfur, which insulates it against cold weather. Three of the raccoon's most distinctive features are its extremely dexterous front paws, its facial mask, and its ringed tail, which are themes in the mythologies of the indigenous peoples of the Americas relating to the animal. The raccoon is noted for its intelligence, as studies show that it is able to remember the solution to tasks for at least three years. It is usually nocturnal and omnivorous, eating about 40% invertebrates, 33% plants, and 27% vertebrates. Raccoon Temporal range: Blancan–present[1] PreꞒꞒOSDCPTJKPgN ↓ Raccoon climbing in tree - Cropped and color corrected.jpg California raccoon (P. l. psora), Lower Klamath National Wildlife Refuge in California Conservation status Least Concern (IUCN 3.1)[2] Scientific classificationedit Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Procyonidae Genus: Procyon Species: P. lotor Binomial name Procyon lotor (Linnaeus, 1758) Raccoon range.png Native range in red, introduced range in blue Synonyms Ursus lotor Linnaeus, 1758 The original habitats of the raccoon are deciduous and mixed forests, but due to their adaptability, they have extended their range to mountainous areas, coastal marshes, and urban areas, where some homeowners consider them to be pests. As a result of escapes and deliberate introductions in the mid-20th century, raccoons are now also distributed across much of mainland Europe, the Caucasus, and Japan. In Europe, the raccoon is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list).[3] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.[4] Though previously thought to be generally solitary, there is now evidence that raccoons engage in gender-specific social behavior. Related females often share a common area, while unrelated males live together in groups of up to four raccoons in order to maintain their positions against foreign males during the mating season and against other potential invaders. Home range sizes vary anywhere from 3 hectares (7.4 acres) for females in cities, to 5,000 hectares (12,000 acres) for males in prairies. After a gestation period of about 65 days, two to five young known as "kits" are born in spring. The kits are subsequently raised by their mother until dispersal in late fall. Although captive raccoons have been known to live over 20 years, their life expectancy in the wild is only 1.8 to 3.1 years. In many areas, hunting and vehicular injury are the two most common causes of death

Raccoon wants to free in zoo. The raccoon (/rəˈkuːn/ or US: /ræˈkuːn/ (listen), Procyon lotor), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of 40 to 70 cm (16 to 28 in), and a body weight of 5 to 26 kg (11 to 57 lb). Its grayish coat mostly consists of dense underfur, which insulates it against cold weather. Three of the raccoon's most distinctive features are its extremely dexterous front paws, its facial mask, and its ringed tail, which are themes in the mythologies of the indigenous peoples of the Americas relating to the animal. The raccoon is noted for its intelligence, as studies show that it is able to remember the solution to tasks for at least three years. It is usually nocturnal and omnivorous, eating about 40% invertebrates, 33% plants, and 27% vertebrates. Raccoon Temporal range: Blancan–present[1] PreꞒꞒOSDCPTJKPgN ↓ Raccoon climbing in tree - Cropped and color corrected.jpg California raccoon (P. l. psora), Lower Klamath National Wildlife Refuge in California Conservation status Least Concern (IUCN 3.1)[2] Scientific classificationedit Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Procyonidae Genus: Procyon Species: P. lotor Binomial name Procyon lotor (Linnaeus, 1758) Raccoon range.png Native range in red, introduced range in blue Synonyms Ursus lotor Linnaeus, 1758 The original habitats of the raccoon are deciduous and mixed forests, but due to their adaptability, they have extended their range to mountainous areas, coastal marshes, and urban areas, where some homeowners consider them to be pests. As a result of escapes and deliberate introductions in the mid-20th century, raccoons are now also distributed across much of mainland Europe, the Caucasus, and Japan. In Europe, the raccoon is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list).[3] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.[4] Though previously thought to be generally solitary, there is now evidence that raccoons engage in gender-specific social behavior. Related females often share a common area, while unrelated males live together in groups of up to four raccoons in order to maintain their positions against foreign males during the mating season and against other potential invaders. Home range sizes vary anywhere from 3 hectares (7.4 acres) for females in cities, to 5,000 hectares (12,000 acres) for males in prairies. After a gestation period of about 65 days, two to five young known as "kits" are born in spring. The kits are subsequently raised by their mother until dispersal in late fall. Although captive raccoons have been known to live over 20 years, their life expectancy in the wild is only 1.8 to 3.1 years. In many areas, hunting and vehicular injury are the two most common causes of death

Three cubs and bear playful. Bearsarecarnivoranmammalsof thefamilyUrsidae. They are classified ascaniforms, or doglike carnivorans. Although only eightspeciesof bears are extant, they are widespread, appearing in a wide variety ofhabitatsthroughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair,plantigradepaws with five nonretractile claws, and short tails. Bears Temporal range:38–0Ma PreꞒ Ꞓ O S D C P T J K Pg N LateEocene– Recent Brown bear(Ursus arctos)Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:CarnivoraInfraorder:ArctoideaFamily:Ursidae G. Fischer de Waldheim, 1817Type genusUrsus Linnaeus, 1758 Subfamilies Hemicyoninae Ursavinae Agriotheriinae Ailuropodinae(Pandas) Tremarctinae(Spectacled Bears) Ursinae(All other bear species) While thepolar bearis mostlycarnivorous, and thegiant pandafeeds almost entirely onbamboo, the remaining six species areomnivorouswith varied diets. With the exception ofcourtingindividuals and mothers with their young, bears are typicallysolitary animals. They may bediurnalornocturnaland have an excellentsense of smell. Despite their heavy build and awkward gait, they are adept runners, climbers, and swimmers. Bears use shelters, such as caves and logs, as their dens; most species occupy their dens during the winter for a long period ofhibernation, up to 100 days. Bears have been hunted sinceprehistorictimes fortheir meatand fur; they have been used forbear-baitingand other forms of entertainment, such as beingmade to dance. With their powerful physical presence, they play a prominent role inthe arts,mythology, and other cultural aspects of various human societies. In modern times, bears have come under pressure through encroachment on their habitats and illegal trade in bear parts, including the Asianbile bearmarket. TheIUCNlists six bear species asvulnerableorendangered, and evenleast concernspecies, such as thebrown bear, are at risk ofextirpationin certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.

Cube and mom bear in swimming pool. Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. Bears Temporal range: 38–0 Ma PreꞒꞒOSDCPTJKPgN Late Eocene – Recent Ours brun parcanimalierpyrenees 1.jpg Brown bear (Ursus arctos) Scientific classificatione Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Infraorder: Arctoidea Family: Ursidae G. Fischer de Waldheim, 1817 Type genus Ursus Linnaeus, 1758 Subfamilies daggerHemicyoninae daggerUrsavinae daggerAgriotheriinae Ailuropodinae (Pandas) Tremarctinae (Spectacled Bears) Ursinae (All other bear species) While the polar bear is mostly carnivorous, and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous with varied diets. With the exception of courting individuals and mothers with their young, bears are typically solitary animals. They may be diurnal or nocturnal and have an excellent sense of smell. Despite their heavy build and awkward gait, they are adept runners, climbers, and swimmers. Bears use shelters, such as caves and logs, as their dens; most species occupy their dens during the winter for a long period of hibernation, up to 100 days. Bears have been hunted since prehistoric times for their meat and fur; they have been used for bear-baiting and other forms of entertainment, such as being made to dance. With their powerful physical presence, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies. In modern times, bears have come under pressure through encroachment on their habitats and illegal trade in bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing.

1) Lions live in a group which is called as "pride"; 10 to 40 lions live in a pride. 2) In the group there are only 1 to 2 adult lions and others are lioness and their cubs. 3) Lions are very protective to themselves, their cubs and their area where they live. 4) Lions fight with other animals in order to protect their food as well as their group. 5) Male lions generally stay with their group and female lions do the hunting. 6) Approximately there are 10 sub-species of lions found in different parts of the world. 7) "South African Lion" or "Transvaal Lion" is considered as the largest sub-species of lions. 8) There are approximately 20000 to 39000 lions left in the world with 650 lions living in India. 9) Excessive hunting of lions has reduced their population worldwide which is posing a threat to ecosystem. 10) Lions are also kept in zoo for entertainment and recreation of the people. Hyenas, orhyaenas(fromAncient Greekὕαινα,hýaina),arefeliformcarnivoranmammals of the familyHyaenidae/haɪˈɛnɪdiː/. With only four extant species (each in its owngenus), it is the fifth-smallestbiological familyin the Carnivora and one of the smallest in the classMammalia.Despite their low diversity, hyenas are unique and vital components of mostAfricanecosystems. Hyenas Temporal range:22–0Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Miocene– recent The four living species of hyena, clockwise from upper left: spotted hyena (Crocuta crocuta), brown hyena (Parahyaena brunnea), aardwolf (Proteles cristata) and striped hyena (Hyaena hyaena)Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:CarnivoraSuborder:FeliformiaInfraorder:ViverroideaFamily:Hyaenidae Gray, 1821Type genusHyaena Brisson, 1762 Genera Crocuta(olive overlay on map) Hyaena(blue on map, includesParahyaena) Parahyaena Proteles(magenta red on map) Adcrocuta† Allohyaena† Belbus† Chasmaporthetes† Herpestides† Hyaenictis† Hyaenotherium† Ictitherium† Ikelohyaena† Leecyaena† Lycyaena† Metahyaena† Miohyaenotherium† Palinhyaena† Pachycrocuta† Pliocrocuta† Plioviverrops† Protictitherium† Thalassictis† Tongxinictis† Tungurictis† Werdelinus† Synonyms ProtelidaeFlower, 1869 Aardwolf, smallest member of the Hyena family, skeleton. (Museum of Osteology) Althoughphylogeneticallycloser tofelinesandviverrids, as part of suborder Feliformia, hyenas are behaviourally andmorphologicallysimilar tocanidsin several elements due toconvergent evolution; both hyenas and canines are non-arboreal,cursorialhunters that catch prey with their teeth rather than claws. Both eat food quickly and may store it, and their calloused feet with large, blunt, nonretractable claws are adapted for running and making sharp turns. However, hyenas' grooming,scent marking, defecation habits, mating and parental behavior are consistent with the behavior of other feliforms. Hyenas feature prominently in the folklore and mythology of human cultures that live alongside them. Hyenas are commonly viewed as frightening and worthy of contempt. In some cultures, hyenas are thought to influence people's spirits, rob graves, and steal livestock and children.Other cultures associate them with witchcraft, using their body parts intraditional African medicine.

Zebra is very funny 😂😂. This smiling very very funny. Zebras (US: /ˈziːbrəz/, UK: /ˈzɛbrəz, ˈziː-/)[1] (subgenus Hippotigris) are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (Equus grevyi), plains zebra (E. quagga), and the mountain zebra (E. zebra). Zebras share the genus Equus with horses and asses, the three groups being the only living members of the family Equidae. Zebra stripes come in different patterns, unique to each individual. Several theories have been proposed for the function of these stripes, with most evidence supporting them as a deterrent for biting flies. Zebras inhabit eastern and southern Africa and can be found in a variety of habitats such as savannahs, grasslands, woodlands, shrublands, and mountainous areas. Zebra Temporal range: Pliocene to recent 5.3–0 Ma PreꞒꞒOSDCPTJKPgN A herd of plains zebra ("Equus quagga") A herd of plains zebras (Equus quagga) in the Ngorongoro Crater in Tanzania Scientific classificatione Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Perissodactyla Family: Equidae Genus: Equus Subgenus: Hippotigris C. H. Smith, 1841 Species †E. capensis E. grevyi †E. koobiforensis †E. mauritanicus †E. oldowayensis E. quagga E. zebra Zebra range.png Modern range of the three living zebra species Zebras are primarily grazers and can subsist on lower-quality vegetation. They are preyed on mainly by lions and typically flee when threatened but also bite and kick. Zebra species differ in social behaviour, with plains and mountain zebra living in stable harems consisting of an adult male or stallion, several adult females or mares, and their young or foals; while Grévy's zebra live alone or in loosely associated herds. In harem-holding species, adult females mate only with their harem stallion, while male Grévy's zebras establish territories which attract females and the species is promiscuous. Zebras communicate with various vocalisations, body postures and facial expressions. Social grooming strengthens social bonds in plains and mountain zebras. Zebras' dazzling stripes make them among the most recognisable mammals. They have been featured in art and stories in Africa and beyond. Historically, they have been highly sought after by exotic animal collectors, but unlike horses and donkeys, zebras have never been truly domesticated. The International Union for Conservation of Nature (IUCN) lists the Grévy's zebra as endangered, the mountain zebra as vulnerable and the plains zebra as near-threatened. The quagga, a type of plains zebra, was driven to extinction in the 19th century. Nevertheless, zebras can be found in numerous protected areas.

1) Lions live in a group which is called as "pride"; 10 to 40 lions live in a pride. 2) In the group there are only 1 to 2 adult lions and others are lioness and their cubs. 3) Lions are very protective to themselves, their cubs and their area where they live. 4) Lions fight with other animals in order to protect their food as well as their group. 5) Male lions generally stay with their group and female lions do the hunting. 6) Approximately there are 10 sub-species of lions found in different parts of the world. 7) "South African Lion" or "Transvaal Lion" is considered as the largest sub-species of lions. 8) There are approximately 20000 to 39000 lions left in the world with 650 lions living in India. 9) Excessive hunting of lions has reduced their population worldwide which is posing a threat to ecosystem. 10) Lions are also kept in zoo for entertainment and recreation of the people. The African buffalo is a very robust species. Its shoulder height can range from 1.0 to 1.7m (3.3 to 5.6ft) and its head-and-body length can range from 1.7 to 3.4m (5.6 to 11.2ft). The tail can range from 70 to 110cm (28 to 43in) long.[3]Compared with otherlarge bovids, it has a long but stocky body (the body length can exceed thewild water buffalo, which is heavier and taller) and short but thickset legs, resulting in a relatively short standing height. Cape buffaloes weigh 425 to 870kg (937 to 1,918lb), with males normally larger than females, reaching the upper weight range.[4]In comparison,African forest buffaloes, at 250 to 450kg (600 to 1,000lb), are only half that size.[5]Its head is carried low; its top is located below the backline. The front hooves of the buffalo are wider than the rear, which is associated with the need to support the weight of the front part of the body, which is heavier and more powerful than the back. Savannah-type buffaloes have black or dark brown coats with age. Old bulls often have whitish circles around their eyes and on their face. Females tend to have more-reddish coats. Forest-type buffaloes are 30-40% smaller, reddish brown in colour, with much more hair growth around the ears and with horns that curve back and slightly up. Calves of both types have red coats. A characteristic feature of thehornsof adult male African buffalo (southern and eastern populations) is that the bases come very close together, forming a shield referred to as a "boss". From the base, the horns diverge downwards, then smoothly curve upwards and outwards and in some cases inwards and or backwards. In large bulls, the distance between the ends of the horns can reach upwards of one metre (the record being 64.5 inches 164cm). The horns form fully when the animal reaches the age of 5 or 6 years old, but the bosses do not become "hard" until it reaches the age of 8 to 9 years old. In cows, the horns are, on average, 10–20% smaller, and they do not have a boss. Forest-type buffalo horns are smaller than those of the savanna-type buffaloes from Southern and East Africa, usually measuring less than 40 centimetres (16in), and are almost never fused.

This Buffalo is very angry charge the tiger. The African buffalo is a very robust species. Its shoulder height can range from 1.0 to 1.7 m (3.3 to 5.6 ft) and its head-and-body length can range from 1.7 to 3.4 m (5.6 to 11.2 ft). The tail can range from 70 to 110 cm (28 to 43 in) long.[3] Compared with other large bovids, it has a long but stocky body (the body length can exceed the wild water buffalo, which is heavier and taller) and short but thickset legs, resulting in a relatively short standing height. Cape buffaloes weigh 425 to 870 kg (937 to 1,918 lb), with males normally larger than females, reaching the upper weight range.[4] In comparison, African forest buffaloes, at 250 to 450 kg (600 to 1,000 lb), are only half that size.[5] Its head is carried low; its top is located below the backline. The front hooves of the buffalo are wider than the rear, which is associated with the need to support the weight of the front part of the body, which is heavier and more powerful than the back. Savannah-type buffaloes have black or dark brown coats with age. Old bulls often have whitish circles around their eyes and on their face. Females tend to have more-reddish coats. Forest-type buffaloes are 30-40% smaller, reddish brown in colour, with much more hair growth around the ears and with horns that curve back and slightly up. Calves of both types have red coats. A characteristic feature of the horns of adult male African buffalo (southern and eastern populations) is that the bases come very close together, forming a shield referred to as a "boss". From the base, the horns diverge downwards, then smoothly curve upwards and outwards and in some cases inwards and or backwards. In large bulls, the distance between the ends of the horns can reach upwards of one metre (the record being 64.5 inches 164 cm). The horns form fully when the animal reaches the age of 5 or 6 years old, but the bosses do not become "hard" until it reaches the age of 8 to 9 years old. In cows, the horns are, on average, 10–20% smaller, and they do not have a boss. Forest-type buffalo horns are smaller than those of the savanna-type buffaloes from Southern and East Africa, usually measuring less than 40 centimetres (16 in), and are almost never fused.

A little fawn bleating.very sweet fawn.so very cute this fawn.

Crocodiles(familyCrocodylidae) ortrue crocodilesare largesemiaquaticreptilesthat live throughout the tropics inAfrica,Asia, theAmericasandAustralia. The term crocodile is sometimes used even more loosely to include allextantmembers of theorderCrocodilia, which includes thealligatorsandcaimans(familyAlligatoridae), thegharialandfalse gharial(familyGavialidae) among other extinct taxa. Crocodiles Temporal range:Eocene–Holocene,46–0Ma PreꞒ Ꞓ O S D C P T J K Pg N Nile crocodile(Crocodylus niloticus)Saltwater crocodile(Crocodylus porosus)Scientific classificationKingdom:AnimaliaPhylum:ChordataClass:ReptiliaOrder:CrocodiliaSuperfamily:CrocodyloideaFamily:Crocodylidae Cuvier, 1807Type genusCrocodylus Laurenti, 1768 Subfamilies Crocodylinae Osteolaeminae Although they appear similar, crocodiles, alligators and the gharial belong to separate biologicalfamilies. The gharial, with its narrowsnout, is easier to distinguish, whilemorphologicaldifferences are more difficult to spot in crocodiles and alligators. The most obvious external differences are visible in the head, with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans. Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, and theteethin the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore, all teeth are visible, unlike an alligator, which possesses in the upper jaw small depressions into which the lower teeth fit. Also, when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define thespecies'family.[1]Crocodiles have morewebbingon the toes of the hindfeetand can better toleratesaltwaterdue to specializedsalt glandsfor filtering out salt, which are present, but non-functioning, in alligators. Another trait that separates crocodiles from other crocodilians is their much higher levels ofaggression.[2] Crocodilesize,morphology,behaviourandecologydiffer somewhat amongspecies. However, they have many similarities in these areas as well. All crocodiles aresemiaquaticand tend to congregate infreshwaterhabitats such asrivers,lakes,wetlandsand sometimes inbrackishwater andsaltwater. They arecarnivorousanimals, feeding mostly onvertebratessuch asfish,reptiles,birdsandmammals, and sometimes oninvertebratessuch asmolluscsandcrustaceans, depending on species and age. All crocodiles aretropicalspecies that, unlike alligators, are very sensitive tocold. They separated from othercrocodiliansduring theEoceneepoch, about 55 million years ago.[3]Many species are at the risk ofextinction, some being classified ascritically endangered.

Monkey on a tree very ezi.

Cat running up a on tree. Cat is very beutyful.

1) Lions live in a group which is called as "pride"; 10 to 40 lions live in a pride. 2) In the group there are only 1 to 2 adult lions and others are lioness and their cubs. 3) Lions are very protective to themselves, their cubs and their area where they live. 4) Lions fight with other animals in order to protect their food as well as their group. 5) Male lions generally stay with their group and female lions do the hunting. 6) Approximately there are 10 sub-species of lions found in different parts of the world. 7) "South African Lion" or "Transvaal Lion" is considered as the largest sub-species of lions. 8) There are approximately 20000 to 39000 lions left in the world with 650 lions living in India. 9) Excessive hunting of lions has reduced their population worldwide which is posing a threat to ecosystem. 10) Lions are also kept in zoo for entertainment and recreation of the people.

Elephant is big animal.