War and Peace Among Baboons and Rhesus and Stump Tail Macaques
heron61 recommended an article today that I absolutely loved, and now I want to recommend it too. It's called "A Natural History of Peace," by Robert M. Sapolsky. The excerpt from it that heron61 quoted, which I'm about to quote to you too, cites a study by the primatologist Frans de Waal, who I own a book by (The Ape and the Sushi Master: Cultural Reflections of a Primatologist), so if you like this article, I can highly recommend de Waal's books. Here's the excerpt:
The second experiment was set up by de Waal and his student Denise Johanowicz in the early 1990s, working with two macaque monkey species. By any human standards, male rhesus macaques are unappealing animals. Their hierarchies are rigid, those at the top seize a disproportionate share of the spoils, they enforce this inequity with ferocious aggression, and they rarely reconcile after fights. Male stump tail macaques, in contrast, which share almost all of their genes with their rhesus macaque cousins, display much less aggression, more affiliative behaviors, looser hierarchies, and more egalitarianism.
Working with captive primates, de Waal and Johanowicz created a mixed-sex social group of juvenile macaques, combining rhesus and stump tails together. Remarkably, instead of the rhesus macaques bullying the stump tails, over the course of a few months, the rhesus males adopted the stump tails' social style, eventually even matching the stump tails' high rates of reconciliatory behavior. It so happens, moreover, that stump tails and rhesus macaques use different gestures when reconciling. The rhesus macaques in the study did not start using the stump tails' reconciliatory gestures, but rather increased the incidence of their own species-typical gestures. In other words, they were not merely imitating the stump tails' behavior; they were incorporating the concept of frequent reconciliation into their own social practices. When the newly warm-and-fuzzy rhesus macaques were returned to a larger, all-rhesus group, finally, their new behavioral style persisted.
This is nothing short of extraordinary. But it brings up one last question: When those rhesus macaques were transferred back into the all-rhesus world, did they spread their insights and behaviors to the others? Alas, they did not. For that, we need to move on to our final case.
And just for good measure, here's another part, one that heron61 didn't already quote:
The results [of a tuberculosis outbreak in a neighboring baboon troop, which infected members of other troops that had aggressively invaded to steal food] 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. . . . But the largest surprise did not come until some years later. Female savanna baboons spend their lives in the troop into which they are born, whereas males leave their birth troop around puberty; a troop's adult males have thus all grown up elsewhere and immigrated as adolescents. 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. . . .
To date, the most interesting hint about the mechanism of transmission is the way recently transferred males are treated by Forest Troop's resident females. In a typical savanna baboon troop, newly transferred adolescent males spend years slowly working their way into the social fabric; they are extremely low ranking -- ignored by females and noted by adult males only as convenient targets for aggression. In Forest Troop, by contrast, new male transfers are inundated with female attention soon after their arrival. Resident females first present themselves sexually to new males an average of 18 days after the males arrive, and they first groom the new males an average of 20 days after they arrive (normal savanna baboons introduce such behaviors after 63 and 78 days, respectively). Furthermore, these welcoming gestures occur more frequently in Forest Troop during the early post-transfer period, and there is four times as much grooming of males by females in Forest Troop as elsewhere. From almost the moment they arrive, in other words, new males find out that in Forest Troop, things are done differently.