Maller killer whales 'can die of loneliness'

Male killer whales are more likely to die if they are not at the centre of their social group, suggests new research.

Scientists found that the most socially isolated males were three times more likely to die in any given year than those in the "most central social positions".

The effect was much stronger in years where food was scarce, and it didn't affect females - possibly because males are larger and need more support from the group to get enough food.