Charity begins at Homo sapiens

Could competition between small groups of our ancestors somehow have turned them into strong reciprocators? Gintis, Boyd and their colleagues believe so. What's more, subsequent research [...] suggests that as humans came to live in larger groups, their attitudes towards reciprocity may have become even more hard-line. [T]hey found that cooperation can become the default behaviour in large groups provided punishers are willing to punish not only those who cheat, but also those who fail to punish cheats. These findings suggest that true altruism, far from being a maladaptation, may be the key to our species' success by providing the social glue that allowed our ancestors to form strong, resilient groups. It is still crucial for social cohesion in today's very different world. "Something like it had to evolve," Gintis says.