ALTRUISM – helping others at a cost to oneself – has been a stubborn thorn in the side of evolutionary biologists. If natural selection favours genes that produce traits which increase the reproductive success of the individuals in which they reside, then altruism is precisely the sort of behaviour that should disappear.
Darwin was acutely aware of the problem that altruism posed for his theory of natural selection. He was particularly worried about the self-sacrificial behaviour that social insects display: how could natural selection explain why a worker bee will defend its hive by stinging an intruder and dying in the process?…
