Human Groups as Units of Selection

David Sloan Wilson The simple theory of natural selection predicts that an individual, whether human or animal, will act selfishly so as to maximize his or her genetic contribution to the next generation. But what of altruism, kindness, and generosity? Where do these traits fit into theories of survival of the fittest? In his Perspective, Wilson discusses an article in The American Naturalist that suggests that these behaviors arose in humans to maximize the survival of groups of hunter-gatherers, and that selection has acted not only on the individual, but on groups as well.