Abstract # 63:

Scheduled for Saturday, August 26, 2017 06:00 PM-08:00 PM: (National Ballroom AB) Poster Presentation


EXPOSURE TO NOVEL FEMALES INCREASES TESTOSTERONE LEVELS IN SOCIALLY-HOUSED MALE CAPUCHIN MONKEYS: EVIDENCE FOR THE CHALLENGE HYPOTHESIS

M. J. Sosnowski1,2, O. B. Tomeo1,2, M. E. Benítez1,2 and S. F. Brosnan1,2,3
1Georgia State University, Department of Psychology, Atlanta, GA 30302, USA, 2Language Research Center, Georgia State University, 3Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University
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     From birds to primates, the challenge hypothesis has successfully predicted changes in androgen profiles in males. Specifically, the challenge hypothesis predicts that testosterone levels in males will fluctuate due to competition for mates. However, one of the challenges of studying the challenge hypothesis in primates is that it is often difficult to distinguishing between testosterone changes due to increased competition, as the hypothesis predicts, or simply as a byproduct of increased sexual activity. Here, we examine the effects of the introduction of novel females on fecal testosterone levels in 7 socially-housed male capuchin (Cebus [Sapajus] apella) monkeys (n=98 fecal samples). We found that males exhibited a drastic increase in testosterone (LMM; beta= 1.88, t= 3.78, p<0.001) within one week of being in visual – but not physical – contact with novel females. Males in neighboring social groups that were in auditory but not visual contact to novel females showed no increase in androgen levels (beta= -0.14, t= -0.26, p=0.79). These results support they hypothesis that males boost testosterone levels due to anticipated challenges over mating opportunities. In addition, we found that dominant males had higher baseline testosterone levels than subordinate males (LMM; beta= 1.69, t= 2.78, p=0.049), providing strong support for the challenge hypothesis in this taxon.