Male chimpanzees who adopt a long-term strategy of violently attacking females get to mate more and father more chimpanzees, shows a study.
Aggression toward females functions as a form of sexual coercion, the researchers determined from the frequent occurrence of such violence at several East African field sites.
These aggressive males were actively solicited for mating by those females at the time of peak fertility, the findings showed, providing strong evidence that male aggression toward females is indeed adaptive.
Critically, aggression over the long term had a greater effect than violence in the immediate context of mating.
Male aggression was not used to force sexual encounters either during or immediately following aggression.
"This indicates that males, particularly those of high rank, successfully employ a strategy of long-term sexual intimidation," says Ian Gilby, an assistant professor at Arizona State University.
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The authors analysed 17 years of observations of the Kasekela chimpanzee community in Gombe National Park, Tanzania.
Researchers used DNA obtained from fecal material to determine the paternity of 31 infants born during the study period.
The rate at which a male directed aggression at a female not only increased the pair's mating frequency, but also significantly increased the probability that he sired her offspring.
While these results may provide clues about the origins of sexual violence in humans, Gilby cautioned, "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."
The findings appeared in the journal Current Biology.