Over at Slate, evolutionary anthropologist Eric Michael Johnson has a fascinating essay about what science has to say about Ayn Rand's theories of human nature. After immersing himself in Rand's work, Johnson set out to uncover what researchers in the field of evolutionary anthropology had discovered about human selfishness and altruism. The result is a thoughtful analysis of how Rand's famous libertarian hero John Galt would have fared during the Pleistocene, a period when human society was in its infancy.

Here's a great excerpt. Johnson writes:

Christopher Boehm has been studying the interplay between the desires of an individual and that of the larger group for more than 40 years . . . In his newest book, Moral Origins: The Evolution of Virtue, Altruism, and Shame, Boehm synthesizes this research to address the question of why, out of all the social primates, are humans so altruistic?

"There are two ways of trying to create a good life," Boehm states. "One is by punishing evil, and the other is by actively promoting virtue." Boehm's theory of social selection does both. The term altruism can be defined as extra-familial generosity (as opposed to nepotism among relatives). Boehm thinks the evolution of human altruism can be understood by studying the moral rules of hunter-gatherer societies. He and a research assistant have recently gone through thousands of pages of anthropological field reports on the 150 hunter-gatherer societies around the world that he calls "Late-Pleistocene Appropriate" (LPA), or those societies that continue to live as our ancestors once did. By coding the reports for categories of social behavior such as aid to nonrelatives, group shaming, or the execution of social deviants, Boehm is able to determine how common those behaviors are.

What he has found is in direct opposition to Ayn Rand's selfish ideal. For example, in 100 percent of LPA societies-ranging from the Andaman Islanders of the Indian Ocean archipelago to the Inuit of Northern Alaska-generosity or altruism is always favored toward relatives and nonrelatives alike, with sharing and cooperation being the most cited moral values. Of course, this does not mean that everyone in these societies always follow these values. In 100 percent of LPA societies there was at least one incidence of theft or murder, 80 percent had a case in which someone refused to share, and in 30 percent of societies someone tried to cheat the group.

What makes these violations of moral rules so instructive is how societies choose to deal with them.