Publication Date


Document Type


First Advisor

Porter, Leila M.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Anthropology


Sexual selection in animals--Costa Rica; Capuchin monkeys--Sexual behavior--Costa Rica; Monkeys--Sexual behavior--Costa Rica; Primates--Sexual behavior--Costa Rica


Researchers examine an animal's behaviors in order to determine how they enhance the animal's fitness. However, animals often exhibit behaviors that expend energy, but do little to improve its proximate survival or reproductive success. These behaviors may represent long-term strategies and are therefore more difficult to document than behaviors that provide immediate benefits. I observed white-faced capuchin social behavior in Costa Rica with the goal of identifying inter-sexual social behaviors that are intentional, regular, and serve no immediate reproductive or survival advantage. For example, interactions with males and non-cycling females provide no immediate reproductive benefits I observed interaction patterns between 11 adults in one social group of C. capucinus during 55.5 hours of observation, contrasting interaction patterns among the alpha male, subordinate males, cycling females, and non-cycling females. Both cycling and non-cycling females interacted significantly more times, but for a shorter duration, with the alpha male than subordinate males. Non-cycling females and subordinate males spent the most time in social interaction (46% of heterosexual social behavior). These data suggest that while both cycling and non-cycling females preferred to associate with the alpha male, inaccessibility or lack of alpha interest may have limited their ability to do so. All adults except the alpha male associated with other group mates in a non-random pattern, suggesting there are benefits of inter-sexual interaction beyond immediate survival or reproduction. There were also unusually high frequencies of same sex social interaction, which may be a reaction to environmental stress as there was anthropogenic disturbance in their home range during the study. Longer studies of this group and of other groups can help to clarify the long-term benefits of inter-sexual social interaction.


Advisors: Leila M. Porter.||Committee members: Mitchell T. Irwin; Katherine C. MacKinnon.||Includes bibliographical references.||Includes illustrations.


iv, 72 pages




Northern Illinois University

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