Male Violence and Sexual Intimidation in a Wild Primate Society

Male Violence and Sexual Intimidation in a Wild Primate Society. Baniel, Alice et al. Current Biology , Volume 27 , Issue 14 , 2163 - 2168.e3, Jul 2017. http://dx.doi.org/10.1016/j.cub.2017.06.013

Highlights
    •Male aggression preferentially targets fertile females in chacma baboons
    •Male aggression represents a major source of injuries for fertile females
    •Male aggressors have higher mating success in the long term, but not immediately
    •These results provide evidence for sexual intimidation in a wild non-human primate

Summary: Sexual violence occurring in the context of long-term heterosexual relationships, such as sexual intimidation, is widespread across human populations [ 1–3 ]. However, its evolutionary origins remain speculative because few studies have investigated the existence of comparable forms of sexual coercion in animals [ 4, 5 ], in which repeated male aggression toward a female provides the aggressor with delayed mating benefits [ 6 ]. Here, we test whether male aggression toward females functions as sexual coercion in wild chacma baboons (Papio ursinus). We found support for all three main predictions of the sexual coercion hypothesis [ 7 ]: male aggression (1) is greatest against cycling females, (2) is costly and represents the main source of injuries for cycling females, and (3) increases male mating success with their victims in the future. Detailed analysis of chronological sequences between aggression and matings ruled out other coercive mechanisms, such as short-term harassment and punishment, by showing that aggression and matings are temporally decoupled. This decoupling may explain why some forms of sexual violence have been largely overlooked in well-studied animal populations despite their likely impact on the fitness of both sexes. Finally, we found no support for alternative hypotheses such as a female preference for aggressive males [ 8, 9 ]. This new, detailed study of the forms and intensity of sexual intimidation in a wild primate suggests that it may be widespread across mammalian societies, with important implications for understanding the evolution of mate choice and sexual conflict in mammals, as well as the origins of human sexual violence.

Keywords: sexual conflict, sexual coercion, intersexual aggression, intimidation, promiscuous mating, injury, mating success, sex roles, primates

My comment: this behavior has been observed in at least two primate species, chimpanzees and now baboons... It could mean that it is a very old behavior in humans, not a recent one or due to socialization (although the environment can ameliorate simptoms or can make them more salient).

Check also: Sexually Coercive Male Chimpanzees Sire More Offspring. Joseph T. Feldblum et al. Current Biology, Volume 24, Issue 23, p2855–2860, 1 December 2014. http://dx.doi.org/10.1016/j.cub.2014.10.039

Highlights
    •Aggression toward sexually receptive females correlated with male mating success
    •Aggression toward non-sexually receptive females was associated with paternity
    •The effect of aggression on paternity was strongest for high-ranking males
    •This represents the first genetic evidence of long-term sexual coercion in mammals

Summary: In sexually reproducing animals, male and female reproductive strategies often conflict [ 1 ]. In some species, males use aggression to overcome female choice [ 2, 3 ], but debate persists over the extent to which this strategy is successful. Previous studies of male aggression toward females among wild chimpanzees have yielded contradictory results about the relationship between aggression and mating behavior [ 4–11 ]. Critically, however, copulation frequency in primates is not always predictive of reproductive success [ 12 ]. We analyzed a 17-year sample of behavioral and genetic data from the Kasekela chimpanzee (Pan troglodytes schweinfurthii) community in Gombe National Park, Tanzania, to test the hypothesis that male aggression toward females increases male reproductive success. We examined the effect of male aggression toward females during ovarian cycling, including periods when the females were sexually receptive (swollen) and periods when they were not. We found that, after controlling for confounding factors, male aggression during a female’s swollen periods was positively correlated with copulation frequency. However, aggression toward swollen females was not predictive of paternity. Instead, aggression by high-ranking males toward females during their nonswollen periods was positively associated with likelihood of paternity. This indicates that long-term patterns of intimidation allow high-ranking males to increase their reproductive success, supporting the sexual coercion hypothesis. To our knowledge, this is the first study to present genetic evidence of sexual coercion as an adaptive strategy in a social mammal.

Also: Survival of the Fittest and the Sexiest: Evolutionary Origins of Adolescent Bullying. Jun-Bin Koh, and Jennifer S. Wong. Journal of Interpersonal Violence, https://www.bipartisanalliance.com/2017/08/survival-of-fittest-and-sexiest.html

And also: We, Too, Are Violent Animals. By Jane Goodall, Richard Wrangham, and Dale Peterson. Those who doubt that human aggression is an evolved trait should spend more time with chimpanzees and wolves  The Wall Street Journal, January 5, 2013, on page C3, https://www.bipartisanalliance.com/2013/01/we-too-are-violent-animals-by-jane.html

And also: Romanticizing the Hunter-Gatherer. William Buckner. Quillette, December 16, 2017. https://www.bipartisanalliance.com/2017/12/romanticizing-hunter-gatherer-despite.html