Biologist Robert Sapolsky is a leading challenger of what he calls the “urban myth of inevitable aggression.” At his Stanford University office, peering out from a tangle of gray-flecked hair and beard, he tells me that primate studies contradict simple biological theories of male belligerence—for example, those that blame the hormone testosterone. Aggression in primates may actually be the cause of elevated testosterone, rather than vice versa. Moreover, artificially increasing or decreasing testosterone levels within the normal range usually just reinforces previous patterns of aggression rather than dramatically transforming behavior; beta males may still be milquetoasts, and alphas still bullies. “Social conditioning can more than make up for the hormone,” Sapolsky says.
Environmental conditions can also override biology among baboons, who, much like chimpanzees, seem hardwired for aggression. Since early 1978, Sapolsky has traveled to Kenya to spy on baboons, including Forest Troop, a group living near a tourist lodge’s garbage dump. Because they had to fight baboons from another troop over the scraps of food, only the toughest males of Forest Troop frequented the dump. In the mid-1980s, all these males died after contracting tuberculosis from contaminated meat.
The epidemic left Forest Troop with many more females than males, and the remaining males were far less pugnacious. Conflict within the troop dropped dramatically; Sapolsky even observed adult males grooming each other. This, he points out in an article in Foreign Affairs, is “nearly as unprecedented as baboons sprouting wings.” The sea change has persisted through the present, as male adolescents who join the troop adapt to its mores. “Is a world of peacefully coexisting human Forest Troops possible?” Sapolsky asks. “Anyone who says, ‘No, it is beyond our nature,’ knows too little about primates, including ourselves.”