Male chimpanzee sexual coercion and mating success at Ngogo

The development of affiliative and coercive reproductive tactics in male chimpanzees

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.2679 ◽

2021 ◽

Vol 288 (1942) ◽

pp. 20202679

Author(s):

Rachna B. Reddy ◽

Kevin E. Langergraber ◽

Aaron A. Sandel ◽

Linda Vigilant ◽

John C. Mitani

Keyword(s):

Mating Success ◽

Sexual Coercion ◽

Adolescent And Young Adult ◽

Adolescent Male ◽

Male Mating ◽

Adult Males ◽

Reproductive Tactics ◽

Males And Females ◽

First Time ◽

Older Males

Like many animals, adult male chimpanzees often compete for a limited number of mates. They fight other males as they strive for status that confers reproductive benefits and use aggression to coerce females to mate with them. Nevertheless, small-bodied, socially immature adolescent male chimpanzees, who cannot compete with older males for status nor intimidate females, father offspring. We investigated how they do so through a study of adolescent and young adult males at Ngogo in Kibale National Park, Uganda. Adolescent males mated with nulliparous females and reproduced primarily with these first-time mothers, who are not preferred as mating partners by older males. Two other factors, affiliation and aggression, also influenced mating success. Specifically, the strength of affiliative bonds that males formed with females and the amount of aggression males directed toward females predicted male mating success. The effect of male aggression toward females on mating success increased as males aged, especially when they directed it toward females with whom they shared affiliative bonds. These results mirror sexual coercion in humans, which occurs most often between males and females involved in close, affiliative relationships.

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Male coercion and the costs of promiscuous mating for female chimpanzees

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.0206 ◽

2007 ◽

Vol 274 (1612) ◽

pp. 1009-1014 ◽

Cited By ~ 121

Author(s):

Martin N Muller ◽

Sonya M Kahlenberg ◽

Melissa Emery Thompson ◽

Richard W Wrangham

Keyword(s):

Mate Choice ◽

Pan Troglodytes ◽

Mating Success ◽

Sexual Coercion ◽

Mating Systems ◽

Female Mate Choice ◽

Male Mating ◽

Pan Troglodytes Schweinfurthii ◽

Male Mating Success ◽

Male Aggression

For reasons that are not yet clear, male aggression against females occurs frequently among primates with promiscuous mating systems. Here, we test the sexual coercion hypothesis that male aggression functions to constrain female mate choice. We use 10 years of behavioural and endocrine data from a community of wild chimpanzees ( Pan troglodytes schweinfurthii ) to show that sexual coercion is the probable primary function of male aggression against females. Specifically, we show that male aggression is targeted towards the most fecund females, is associated with high male mating success and is costly for the victims. Such aggression can be viewed as a counter-strategy to female attempts at paternity confusion, and a cost of multi-male mating.

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