Behave: The Biology of Humans at Our Best and Worst

by Robert M. Sapolsky

Jane Goodall blew off everyone’s socks in the 1960s by reporting the now-iconic fact that chimps make tools. Her study subjects modified twigs by stripping off the leaves and pushing them into termite mounds; termites would bite the twig, still holding on when it was pulled out, yielding a snack for the chimps.

Why have stratified cultures dominated the planet, generally replacing more egalitarian ones? For population biologist Peter Turchin, the answer is that stratified cultures are ideally suited to being conquerors—they come with chains of command.34 Both empirical and theoretical work suggests that in addition, in unstable environments stratified societies are “better able to survive resource shortages [than egalitarian cultures] by sequestering mortality in the lower classes.” In other words, when times are tough, the unequal access to wealth becomes the unequal distribution of misery and death. Notably, though, stratification is not the only solution to such instability—this is where hunter-gatherers benefit from being able to pick up and move.