Paternal care and the evolution of exaggerated sexual swellings in primates

Journal Article

The exaggerated sexual swellings exhibited by females of some primate species have been of interest to evolutionary biologists since the time of Darwin. We summarize existing hypotheses for their function and evolution and categorize these hypotheses within the context of 3 types of variation in sexual swelling size: 1) variation within a single sexual cycle, 2) variation between the sexual cycles of a single female, and 3) differences between females. We then propose the Paternal Care Hypothesis for the function of sexual swellings, which posits that exaggerated sexual swellings function to elicit the right quantity and quality of male care for a female's infant. As others have noted, swellings may allow females to engender paternity confusion, or they may allow females to confer relative paternal certainty on one male. Key to our hypothesis is that both of these scenarios create an incentive for one or more males to provide care. This hypothesis builds on previous hypotheses but differs from them by highlighting the elicitation of paternal care as a key function of swellings. Our hypothesis predicts that true paternal care (in which males accurately differentiate and provide assistance to their own offspring) will be most common in species in which exaggerated swellings accurately signal the probability of conception, and males can monopolize females during the window of highest conception probability. Our hypothesis also predicts that females will experience selection to behave in ways that either augment paternity confusion or enhance paternal certainty depending on their social and demographic contexts. © 2012 The Author.

Full Text

Duke Authors

Cited Authors

  • Alberts, SC; Fitzpatrick, CL

Published Date

  • 2012

Published In

Volume / Issue

  • 23 / 4

Start / End Page

  • 699 - 706

PubMed ID

  • 24771988

International Standard Serial Number (ISSN)

  • 1045-2249

Digital Object Identifier (DOI)

  • 10.1093/beheco/ars052