Warfare, culture and human evolution

From Blood and treasure (The Economist, 4 June 2009):

Two of the oddest things about people are morality and culture. Neither is unique to humans, but Homo sapiens has both in an abundance missing from other species. Indeed, that abundance—of concern for the well-being of others, (even unrelated others), and of finely crafted material objects both useful and ornamental—is seen by many as the mark of man, as what distinguishes humanity from mere beasts.

How these human traits evolved is controversial. But two papers in this week's Science may throw light on the process. In one, Samuel Bowles of the Santa Fe Institute in New Mexico fleshes out his paradoxical theory that much of human virtue was forged in the crucible of war. Comrades in arms, he believes, become comrades in other things, too.

In the other paper, Mark Thomas and his colleagues at University College, London, suggest that cultural sophistication depends on more than just the evolution of intelligence. It also requires a dense population. If correct, this would explain some puzzling features of the archaeological record that have hitherto been put down to the arbitrary nature of what has survived to the present and what has not.

Dr Bowles's argument starts in an obscure cranny of evolutionary theory called group selection. This suggests that groups of collaborative individuals will often do better than groups of selfish ones, and thus prosper at their expense. It is therefore no surprise, according to group-selectionists, that individuals might be genetically predisposed to act in self-sacrificial ways.

This good-of-the-group argument was widely believed until the 1960s, when it was subject to rigorous scrutiny and found wanting. The new theory does not pitch groups against groups, or even individuals against individuals, but genes against genes. It does not disallow altruistic behaviour, but requires that this evolve in a way that promotes the interest of a particular gene—for example by helping close relatives who might also harbour the gene in question. The “selfish gene” analysis, so called after a book by Richard Dawkins, makes good-of-the-group outcomes almost impossible to achieve.

~ more... ~