After observing the mating habits of chacma baboons living in the wild over a four-year period, researchers have found that males of the species often use long-term sexual intimidation to control their mates. The findings reported in Current Biology on July 6 suggest that this mating strategy has a long history in primates, including humans, and may be widespread across social mammals -- especially when males of a species are typically larger than females. Baniel says she and her PhD supervisors, Guy Cowlishaw from the Zoological Society of London, UK, and Elise Huchard at CNRS in Montpellier, France, were curious about male violence and sexual intimidation in the baboons living in Namibia in part because no one had ever witnessed a male baboon forcing a female to mate with him. They wondered if males might be coercing females in less obvious ways. She also noticed that males in those relationships were often aggressive toward their female partners.
Sexual Bullying May Lie Deep in Our DNA, Baboon Study Shows
It is the northernmost of all the baboons, being native to the Horn of Africa and the southwestern tip of the Arabian Peninsula. These regions provide habitats with the advantage for this species of fewer natural predators than central or southern Africa where other baboons reside. The hamadryas baboon was a sacred animal to the ancient Egyptians and appears in various roles in ancient Egyptian religion , hence its alternative name of 'sacred baboon'. Apart from the striking sexual dimorphism males are nearly twice as large as females, which is common to all baboons  this species also shows differences in coloration among adults. Adult males have a pronounced cape mane and mantle , silver-white in color, which they develop around the age of ten, while the females are capeless and brown all over.
They beat up on females for no apparent reason, biting them hard enough to make them bleed and harassing them in general. And this bullying seems to pay off. The aggressive male baboons were more likely to mate with their victims when they became fertile, researchers reported Thursday. They say their findings add to growing evidence that sexual aggression may be hard-wired into our genes. It's only one small piece of the puzzle, but the researchers say understanding the roots of such behavior can help explain why it's so common among people.