The opposite of altruism is human?

I am a casual observer of birds. One behaviour I have often witnessed is their reaction to another bird carrying food in its beak. Herring gulls show an excellent example of the behaviour.In this situation herring gulls engage in an acrobatic chase, four or five gulls at a time chasing one. There never appears to be any mid-air contact, but plenty of dive-bombing, and the chase invariable seems to end with the morsel being dropped and lost.At first I dismissed this as a wasteful side effect of greed. Then I noticed that the fugitive rarely seemed to be doing its best to escape. In fact,, having outwitted the chasing mob, the fugitive sometimes returned to reengage them before eventually losing out and dropping the morsel.I have seen no obvious reason for this behaviour short of demonic pleasure! It does not appear to be adults encouraging yearlings to fly, or anything of that nature.

This is in the first paragraph of the article you quoted in your opening post.Also, the title of your thread is asking if the opposite of altruism is specifically human.Therefore, does it not make sense to give examples of non-human behaviour which is opposite to altruism?

I am sure one could waste a lot of time researching a truism if ones definition of altruism is sufficiently unfortunate.Unless you can define what makes the nature of torment "sport" in the one instance and "the opposite of altruism" in the other, you may simply end up "discovering" that humans are human.