In 1975 Harvard biologist E. O. Wilson published Sociobiology, perhaps the most powerful refinement of evolutionary theory since On the Origin of Species. Darwin’s theory of natural selection postulated a brutal world in which individuals vied for dominance. Wilson promoted a new perspective: Social behaviors were often genetically programmed into species to help them survive, he said, with altruism— self-destructive behavior performed for the benefit of others—bred into their bones.
In the context of Darwinian selection, such selflessness hardly made sense. If you sacrificed your life for another and extinguished your genes, wouldn’t the engine of evolution simply pass you by? Wilson resolved the paradox by drawing on the theory of kin selection. According to this way of thinking, “altruistic” individuals could emerge victorious because the genes that they share with kin would be passed on. Since the whole clan is included in the genetic victory of a few, the phenomenon of beneficial altruism came to be known as “inclusive fitness.” By the 1990s it had become a core concept of biology, sociology, even pop psychology.
So the scientific world quaked last August when Wilson renounced the theory that he had made famous. He and two Harvard colleagues, Martin Nowak and Corina Tarnita, reported in Naturethat the mathematical construct on which inclusive fitness was based crumbles under closer scrutiny. The new work indicates that self-sacrifice to protect a relation’s genes does not drive evolution. In human terms, family is not so important after all; altruism emerges to protect social groups whether they are kin or not. When people compete against each other they are selfish, but when group selection becomes important, then the altruism characteristic of human societies kicks in, Wilson says. We may be the only species intelligent enough to strike a balance between individual and group-level selection, but we are far from perfect at it. The conflict between the different levels may produce the great dramas of our species: the alliances, the love affairs, and the wars.
