Tia Ghose discusses some recent findings on the sexual aggression of male chimpanzees and (given that humans are closely related to chimps) looks for parallels in human behaviour:
Male chimpanzees that wage a campaign of sustained aggression against females sire more offspring than their less violent counterparts, new research finds.
The results suggest that such nasty behavior from males evolved because it gave the meanest males a reproductive advantage, said study co-author Ian Gilby, a primatologist at Arizona State University in Phoenix.
This chimpanzee behavior could also provide some insight into the roots of sexual aggression in men.
“It is possible that in our early ancestors there may have been an adaptive value to male aggression against females,” Gilby said.
Though the findings are in chimpanzees, they lend credence to the notion that male sexual aggression in humans may have some genetic or evolutionary basis, Gilby said.
On the other hand, drawing parallels can be perilous. Humans diverged from chimpanzees at least 7 million years ago, and the human mating system looks very different from chimps’ violent, multi-male, multi-female system. Humans form pair bonds and have varied and complex mating strategies and behaviors. And most men aren’t brutes to their partners.
“We definitely don’t mean to say this excuses or fully explains violence in this way in humans,” Gilby said.
The study’s findings may provide fodder for a long-standing debate in evolutionary biology about whether rape and sexual aggression are evolutionarily advantageous in humans, said William McKibbin, an evolutionary psychologist at the University of Michigan–Flint, who was not involved in the study. No studies in humans have ever shown that rape increases reproductive success, he added.