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Intersexual food transfer among orangutans: do females test males for coercive tendency?


van Noordwijk, M A; van Schaik, C P (2009). Intersexual food transfer among orangutans: do females test males for coercive tendency? Behavioral Ecology and Sociobiology, 63(6):883-890.

Abstract

Tolerated transfer of food among adults is rare among primates, except in humans. Here, we present data on a consistent pattern of tolerated intersexual transfer of food (held in hand, foot, or mouth by the owner) among adult orangutans, in two different natural populations (Pongo abelii and Pongo pygmaeus wurmbii), based on ca. 9,000 h of focal observation per site. Although rare, intersexual food transfers were disproportionately from
males to sexually active females and involved food that was equally available to both sexes. There was no evidence for direct trading of food for social favors (mating, grooming, or agonistic support) or for sharing under pressure
of harassment. However, females frequently protested with loud screams when males, especially unflanged ones, attempted to take food they possessed, and also when males responded aggressively to their taking attempt. Since associations ended sooner when the female emitted noisy
calls, a male who did not allow a female to take food from him risked losing the association. These findings support the hypothesis that by taking food, a sexually active female may test the male's tendency toward violence. Thus,
intersexual food taking in orangutans is based on female leverage, resulting in a species-wide female entitlement to male “generosity”. The inhibition of food defense required for this kind of transaction may also form the basis for
sharing patterns among species in which nutritional benefits have become important, such as chimpanzees and perhaps human foragers.

Abstract

Tolerated transfer of food among adults is rare among primates, except in humans. Here, we present data on a consistent pattern of tolerated intersexual transfer of food (held in hand, foot, or mouth by the owner) among adult orangutans, in two different natural populations (Pongo abelii and Pongo pygmaeus wurmbii), based on ca. 9,000 h of focal observation per site. Although rare, intersexual food transfers were disproportionately from
males to sexually active females and involved food that was equally available to both sexes. There was no evidence for direct trading of food for social favors (mating, grooming, or agonistic support) or for sharing under pressure
of harassment. However, females frequently protested with loud screams when males, especially unflanged ones, attempted to take food they possessed, and also when males responded aggressively to their taking attempt. Since associations ended sooner when the female emitted noisy
calls, a male who did not allow a female to take food from him risked losing the association. These findings support the hypothesis that by taking food, a sexually active female may test the male's tendency toward violence. Thus,
intersexual food taking in orangutans is based on female leverage, resulting in a species-wide female entitlement to male “generosity”. The inhibition of food defense required for this kind of transaction may also form the basis for
sharing patterns among species in which nutritional benefits have become important, such as chimpanzees and perhaps human foragers.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Anthropology
Dewey Decimal Classification:300 Social sciences, sociology & anthropology
Language:English
Date:2009
Deposited On:11 Aug 2009 14:38
Last Modified:21 Nov 2017 14:16
Publisher:Springer
ISSN:0340-5443
Additional Information:The original publication is available at www.springerlink.com
Publisher DOI:https://doi.org/10.1007/s00265-009-0728-3

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