Presentation Title

Sex Differences in Aggression of Captive Hamadryas Baboons

Presenter Information

John LaRueFollow

Faculty Mentor

Lynne E Miller, Ph.D., Department of Anthropology, MiraCosta College

Start Date

17-11-2018 8:15 AM

End Date

17-11-2018 8:30 AM

Location

C153

Session

Oral 1

Type of Presentation

Oral Talk

Subject Area

behavioral_social_sciences

Abstract

Sexual selection theory details how environmental pressures operate differently on the evolution of males and females. As the reproductive processes of gestation and lactation are calorically costly, the reproductive fitness of females is heavily influenced by access to food. Conversely, the fitness of males is dictated by access to rare sexually receptive females, resulting in high male-male competition. In primates, this competition generally leads males to be more aggressive than females. This study tested the hypothesis that sexual selection will cause male primates to exhibit higher levels of aggressive behaviors than females. Additionally, if males use aggression to secure mates, then most recipients of male aggression will be other males. Likewise, if females increase their fitness through competition for food, then most recipients of female aggression will be other females. The subjects studied were one group of captive hamadryas baboons (Papio hamadryas), composed of 21 individuals, living in a large open enclosure at the San Diego Zoo. Data were collected by focal behavioral sampling of aggressive behaviors and threat displays. The data support both predictions, with males accounting for 43 (89.5%) of the 48 total recorded aggressive behaviors, while females only performed 5 (10.4%) behaviors (x² = 37.70). Furthermore, of the 43 aggressive acts committed by males, 34 (79%) were directed towards other males, while only nine (21%) were directed towards females. Moreover, of the five recorded aggressive behaviors committed by females, 100% were directed towards other females, with 0% directed towards males (x² = 13.55). Like humans, hamadryas baboons represent a primate species whose ancestors left the forests for the savannahs millions of years ago. Furthermore, like most human societies, hamadryas baboons exhibit a male-bonded social organization. Thus, research such as this can elucidate patterns of aggression among early and modern humans.

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Nov 17th, 8:15 AM Nov 17th, 8:30 AM

Sex Differences in Aggression of Captive Hamadryas Baboons

C153

Sexual selection theory details how environmental pressures operate differently on the evolution of males and females. As the reproductive processes of gestation and lactation are calorically costly, the reproductive fitness of females is heavily influenced by access to food. Conversely, the fitness of males is dictated by access to rare sexually receptive females, resulting in high male-male competition. In primates, this competition generally leads males to be more aggressive than females. This study tested the hypothesis that sexual selection will cause male primates to exhibit higher levels of aggressive behaviors than females. Additionally, if males use aggression to secure mates, then most recipients of male aggression will be other males. Likewise, if females increase their fitness through competition for food, then most recipients of female aggression will be other females. The subjects studied were one group of captive hamadryas baboons (Papio hamadryas), composed of 21 individuals, living in a large open enclosure at the San Diego Zoo. Data were collected by focal behavioral sampling of aggressive behaviors and threat displays. The data support both predictions, with males accounting for 43 (89.5%) of the 48 total recorded aggressive behaviors, while females only performed 5 (10.4%) behaviors (x² = 37.70). Furthermore, of the 43 aggressive acts committed by males, 34 (79%) were directed towards other males, while only nine (21%) were directed towards females. Moreover, of the five recorded aggressive behaviors committed by females, 100% were directed towards other females, with 0% directed towards males (x² = 13.55). Like humans, hamadryas baboons represent a primate species whose ancestors left the forests for the savannahs millions of years ago. Furthermore, like most human societies, hamadryas baboons exhibit a male-bonded social organization. Thus, research such as this can elucidate patterns of aggression among early and modern humans.