Altruism in chimps

There is a nice site for discussion of recent research on science topics http://notexactlyrocketscience.wordpress.com/. The post on June 25, 2007 discusses some recent research on altruism in chimps:
"Many scientists have argued that only humans show true altruistic behaviour. But a group of Ugandan chimps is set to change all that by showing clear signs of true selflessness, helping other unrelated chimps with no desire for reward.
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Now, Felix Warneken and colleagues form the Max Planck Institute for Evolutionary Anthropology have found compelling evidence that we are not alone. Contrary to previous studies, they have found that chimps also behave altruistically in a very human way. They help out unrelated strangers without expectation of reward, and even go to great lengths to do so.
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It’s particularly fascinating that rewards in the first two tests didn’t affect the chimps’ behaviour. This suggests that chimps don’t continually analyse the pros and cons of helping their fellow – if they did, the reward would have motivated them to help even more often.

Instead, de Waal believes that the chimps have evolved psychological systems that steer them towards selflessness. In essence, natural selection has done the analysis for them and decided that altruistic behaviour works to its advantage in the long run. Selfless behaviour then, can evolve for selfish reasons, and that strikes to the very core of the debate on altruism."

See also the June 23 post on "Resistance to an extinct virus makes us more vulnerable to HIV" which is also discussed by Carl Zimmer in "The Loom" on June 21:http://scienceblogs.com/loom/