Aggressive Male Chimps Get to be Fathers

It seems that female chimps are essentially bullied into mating, as new research shows aggressive males of this species are more likely to father offspring over time.

According to findings published in the journal Current Biology, paternity tests indicate that this type of sexual coercion is a strategy that males have adapted over the long term, realizing the effectiveness of sheer intimidation.

"These results seem to suggest that males are selected to be aggressive toward females to increase their paternity success, which explains why male-female aggression is observed in so many chimpanzee populations," lead author Joseph Feldblum of Duke University said in a press release.

Male chimpanzees have long been known to exhibit aggressive behavior towards females, but previous research has been contradictory, with studies finding evidence both for and against the presence of sexual coercion in wild chimps.

To settle the debate once and for all, Feldblum and his colleagues observed a chimpanzee community living in Tanzania's Gombe National Park that had been under close observation for the last 50 years. Using this particular population proved to be advantageous for researchers who could thus determine not only which chimps had mated with each other, but also who the biological fathers were of nearly all the individuals born in the community since 1995.

Further analysis showed that male hostility during a female's sexually receptive, or swollen, period led to more frequent mating, but not greater paternity success. So even though these instances created more opportunities to father offspring, the males could not capitalize.

On the other hand, high-ranking males that exhibited violence towards females when they weren't swollen were actually rewarded for their bullying behavior, resulting in more offspring and reproductive success.

Though the results establish that male sexual coercion works to sire more offspring among these primates, it in no way suggests that the same behavior can apply to humans, despite our close evolutionary ties with chimps.