Thursday, July 21, 2011

The Diversity of Baboon Culture

I am posting this story here mainly so I can find it again the next time one of these debates comes up. A certain sort of evolutionary determinist likes to argue that some things about human society cannot change, and in the course of this argument he or she is bound to cite some primate studies about chimpanzee mating or baboon aggression. But chimpanzees and baboons are not all alike. They have, in fact, highly diverse personalities. Chimpanzee and baboon troops are also quite diverse, often, it seems, because of the personalities of the dominant animals. In support of this notion (and so I can find it again), I give you the Tale of the Pacifist Baboon Troop:
In the early 1980s, "Forest Troop," a group of savanna baboons I had been studying -- virtually living with -- for years, was going about its business in a national park in Kenya when a neighboring baboon group had a stroke of luck: its territory encompassed a tourist lodge that expanded its operations and consequently the amount of food tossed into its a garbage dump. Baboons are omnivorous, and "Garbage Dump Troop" was delighted to feast on leftover drumsticks, half-eaten hamburgers, remnants of chocolate cake, and anything else that wound up there. Soon they had shifted to sleeping in the trees immediately above the pit, descending each morning just in time for the day's dumping of garbage. (They soon got quite obese from the rich diet and lack of exercise, but that is another story.)

The development produced nearly as dramatic a shift in the social behavior of Forest Troop. Each morning, approximately half of its adult males would infiltrate Garbage Dump Troop's territory, descending on the pit in time for the day's dumping and battling the resident males for access to the garbage. The Forest Troop males that did this shared two traits: they were particularly combative (which was necessary to get the food away from the other baboons), and they were not very interested in socializing (the raids took place early in the morning, during the hours when the bulk of a savanna baboon's daily communal grooming occurs).

Soon afterward, tuberculosis, a disease that moves with devastating speed and severity in nonhuman primates, broke out in Garbage Dump Troop. Over the next year, most of its members died, as did all of the males from Forest Troop who had foraged at the dump. The results were that Forest Troop was left with males who were less aggressive and more social than average and the troop now had double its previous female-to-male ratio.

The social consequences of these changes were dramatic. There remained a hierarchy among the Forest Troop males, but it was far looser than before: compared with other, more typical savanna baboon groups, high-ranking males rarely harassed subordinates and occasionally even relinquished contested resources to them. Aggression was less frequent, particularly against third parties. And rates of affiliative behaviors, such as males and females grooming each other or sitting together, soared. There were even instances, now and then, of adult males grooming each other – a behavior nearly as unprecedented as baboons sprouting wings. . . By the early 1990s, none of the original low aggression/high affiliation males of Forest Troop’s tuberculosis period was still alive; all of the group’s adult males had joined after the epidemic. Despite this, the troop’s unique social milieu persisted – as it does to this day, some 20 years after the selective bottleneck.

In other words, adolescent males that enter Forest Troop after having grown up elsewhere wind up adopting the unique behavioral style of the resident males. As defined by both anthropologists and animal behaviorists, “culture” consists of local behavioral variations, occurring for nongenetic and nonecological reasons, that last beyond the time of their originators. Forest Troop’s low aggression/high affiliation society constitutes nothing less than a multigenerational benign culture.

That's from primatologist Robert Sapolsky.

I believe very much in biology, and I also believe that our brains are just complex tissues that can get sick or damaged in lots of ways. So I suspect we will never be free from violence, cruelty, rape, and other scourges. But human cultures vary dramatically in how much violence, cruelty, and so on they experience. We can change these things, if we work at it.

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