Sex and Temperament in Humans and Other Primate Societies

Michael Wilson (University of Minnesota)

September 28, 2021, 12:15–13:15


Room Auditorium 4


Temperament varies greatly among primate species. Among our closest living relatives, chimpanzees are impulsive, excitable, and aggressive within and between groups, while bonobos are calmer, more peaceful, and capable of peaceful intergroup interactions. Such variation in temperament may result from selection for effective reproductive competition. Here we consider three cases of how variation in patterns of female grouping and sexual signaling may affect male behavioral strategies. (1) Male chimpanzees in the Mitumba community, Gombe National Park, Tanzania, engaged in an exceptionally high rate of within-group killing. Comparisons within Gombe and across chimpanzee study sites indicate that the best predictor of rates of within-group killing among males is the degree to which mating opportunities with fertile females can be monopolized. In a community with few females, the highest ranking male can monopolize mating opportunities completely, greatly raising the stakes in competition for status. (2) To test the hypothesis that a suite of differences between bonobos and chimpanzees results from differences in the intensity of competition among males for mating opportunities, we analyzed long-term data from Gombe’s Kasekela community. Rates of participation in hunting monkeys and patrolling territorial boundaries correlated positively with rate of mating with fertile females. (3) In virtual primates, female group size affects whether males achieve greater reproductive success by adopting a ‘loyalist’ strategy (rarely moving from one female group to another) versus a ‘rover’ strategy (moving more frequently in search of fertile females). These findings suggest that the relatively calm temperaments of human males result from evolution in societies with long-term pair-bonds and relatively low reproductive skew.


Michael Wilson (University of Minnesota), Sex and Temperament in Humans and Other Primate Societies, IAST Lunch Seminar, Toulouse: IAST, September 28, 2021, 12:15–13:15, room Auditorium 4.