Aggressive male chimps are more likely than timid members of the colonies to engage in frequent mating and father offspring, according to a new finding from Arizona State University.
Male chimpanzees can frequently attack females during the mating process. Some of the injuries sustained during these rituals can be serious. Researchers studying the mating process of chimps in Kibale National Park in Uganda determined the violent acts are carried out as a form of sexual coersion carried out by male chimpanzees on females.
The behavior was particularly effective for high-ranking animals in the chimpanzee hierarchy. Those that continued to violently dominate females, even when they were not in the mating part of their cycle, mated more often.
"This indicates that males, particularly those of high rank, successfully employ a strategy of long-term sexual intimidation," Ian Gilby, from the School of Human Evolution and Social Change and Arizona State University, said.
The study observed the primates over a course of 17 years. Parentage of the chimpanzees was determined by DNA analysis carried out on scat from the creatures.
Aggressive male chimpanzees were not only more likely to mate with females than their mellower comrades, but the "bad boy" chimps were also selected by females in heat more frequently.
During the mating process, males can viciously attack females, kicking their mates, ripping out their fur, and violently beating them. Some masculine chimps will kill offspring of females with whom they wish to mate, in order to reduce competition for the mother's time to raise his own youngster.
Female chimpanzees combat this behavior by mating with most of the males in the group, confusing the males as to the paternity of their babies. However, females reserve the most fertile time of their reproductive cycle for mating with top-ranked males.
Chimpanzees are the closest living relatives to human beings, as the two species separated just seven million years ago. This study is leading some people to question the impact this research could have for understanding human behavior.
"We should be careful not to jump to conclusions. Chimpanzees are one of our closest living relatives, but 7 million years of evolution separate us, and our mating systems are very different. Nevertheless, recognizing the adaptive value of male-female aggression in chimpanzees may inevitably help us to understand, and hopefully prevent, similar behavior among humans," Gilby stated in a press release.
Male-on-female violence in the reproductive cycle of chimpanzees was detailed in the journal Current Biology.