Evolutionary psychology is a powerful set of ideas, from which I’ve drawn great insight over the last decade or so.  But like most of its fans, I didn’t realize I was missing half of the story.  You see, academic anthropology departments have long been split into two warring camps: physical vs. cultural anthropology.

Physical anthropologists include folks who dig up old skulls, and who work with animals like chimps. Cultural anthropologists focus on studying humans in diverse societies, and are more hostile to evo psych. From a review of  Evolutionary Thought in Psychology: A Brief History:

Cultural anthropology was a different story. Raw self-interest and out-group hostility played a larger role. Plotkin argues that the rise of cultural anthropology was, in no small measure, a reaction against evolutionary approaches in the social sciences. On the one hand, it was a classic turf war. Cultural anthropologists feared that an evolutionarily based social science would put them out of business, and this motivated them to drive out the evolutionary infidel. On the other hand, many leading cultural anthropologists, particularly Franz Boas and his students, who were distrustful of the theory of natural selection. They argued that cultural expressions and the science of culture had little to do with biology and that everything from human sex differences to aggression were purely cultural.

Yes, it made political sense for evo psych folks to rely more on data from physical anthro folks who approved of their work, and to neglect the data of the cultural anthro folks hostile to their work. But it doesn’t make scientific sense.

Yes, since human psychology evolved from the psychology of earlier primate ancestors, studying other primates can give us important clues about the origins of our psychology.  And yes, physical fossils like skulls give us clues to how our ancestors changed.  But cultural anthropologists have studied in great detail recent human societies that seem to have retained much of the lifestyle of our distant nomadic forager ancestors. Surely these contain powerful clues about the social environment in which human psychology evolved.

Which brings me to Christopher Boehm and his 1999 classic  Hierarchy in the Forest, a book that has greatly influenced my thinking over the last few months.  Boehm studied on both sides of the anthropology divide, working with both chimps and “primitive” humans.  He has fashioned a powerful synthesis. A few quotes:

As members of bands or tribes, humans can be quite egalitarian … Individuals who otherwise would be subordinated are clever enough to form a large and united political coalition. … Because the united subordinates are constantly putting down the more assertive alpha types in their midst, egalitarianism is in effect a bizarre type of political hierarchy: the weak combine forces to actively dominate the strong. … They must continue such domination if they are to remain autonomous and equal, and prehistorically we shall see that they appear to have done so very predictably as long as hunting bands remained mobile. … The egalitarian political lifestyle of Upper Paleolithic hunter-gatherers could have profoundly affected our evolving social nature.

The three African great apes, with whom we share this rather recent Common Ancestor, are notably hierarchical. … Starting about five thousand years ago … people were beginning to live increasingly in chiefdoms, societies with highly privileged individuals … But before twelve thousand years ago, humans basically were egalitarian.  They lived in what might be called societies of equals, with minimal political centralization and no social classes. Everyone participated in group decisions, and outside the family there were no dominators. For more than five millennia now, the human trend has been toward hierarchy rather than equality. But the past several centuries have witnessed sporadic but highly successful attempts to reverse this trend. …

Large-game hunting brings special reputational benefits. Large game is shared by the entire band, and the resulting prestige lends itself to political ascendancy.