Bully chimps get more kids: study

In the chimpanzee world, treating her mean does keep her keen.

Aggressive male chimps who regularly bully females get to father more babies than others over time, a study by evolutionary anthropologists says.

The findings, in the journal Current Biology, come from Joseph Feldblum of Duke University and colleagues who looked at a chimpanzee community in Tanzania's Gombe National Park that had been under close observation for the last 50 years.

They knew which chimps had mated and the biological fathers of nearly all chimpanzees born in the community since 1995, based on genetic tests of paternity.

They were curious about the surprising amount of aggression males show towards female group mates, so they examined the effect of male aggression toward females both when the females were sexually receptive and when they were not.

Male aggression during a periods of receptiveness led to more frequent mating but not greater paternity success.

On the other hand, high-ranking males that showed aggression toward females who hadn't come into estrus were rewarded for their bullying with more offspring, the paper says.

"The findings suggest long-term intimidation allows high-ranking males to increase their reproductive success, offering what may be the first genetic evidence of sexual coercion as an adaptive strategy in any social mammal."

But don't try this at home.

The glaring difference between chimpanzee and human mating behaviour is that in chimpanzees females mate promiscuously with most male group mates during most cycles, while human females do not, Feldblum says.

"Thus, the system that favours male coercion in chimpanzees is not present in humans to favour this behaviour."

He now wants to find out whether some males might find success in paternity in kinder, gentler ways, for instance by spending more time grooming females.