@article{2242816952bb4d2eaa157d7ea1471b43,
title = "Experimental evidence that female rhesus macaques (Macaca mulatta) perceive variation in male facial masculinity",
abstract = "Among many primate species, face shape is sexually dimorphic, and male facial masculinity has been proposed to influence female mate choice and male-male competition by signalling competitive ability. However, whether conspecifics pay attention to facial masculinity has only been assessed in humans. In a study of free-ranging rhesus macaques, Macaca mulatta, we used a two-alternative look-time experiment to test whether females perceive male facial masculinity. We presented 107 females with pairs of images of male faces-one with a more masculine shape and one more feminine-and recorded their looking behaviour. Females looked at the masculine face longer than at the feminine face in more trials than predicted by chance. Although there was no overall difference in average look-time between masculine and feminine faces across all trials, females looked significantly longer at masculine faces in a subset of trials for which the within-pair difference in masculinity was most pronounced. Additionally, the proportion of time subjects looked toward the masculine face increased as the within-pair difference in masculinity increased. This study provides evidence that female macaques perceive variation in male facial shape, a necessary condition for intersexual selection to operate on such a trait. It also highlights the potential impact of perceptual thresholds on look-time experiments.",
keywords = "Facial masculinity, Look-time experiment, Mate choice, Sexual dimorphism",
author = "Rosenfield, {Kevin A.} and Stuart Semple and Georgiev, {Alexander V.} and Dario Maestripieri and Higham, {James P.} and Constance Dubuc",
note = "Funding Information: Ethics. The study was approved by the IACUC of the University of Puerto Rico, Medical Sciences Campus (protocol no. A0100108). All applicable international, national and/or institutional guidelines for the care and use of animals (in particular non-human primates) were followed. All procedures performed involving animals were in accordance with the ethical standards of the institution(s) at which the study was conducted. Data accessibility. All data and code related to this study have been: (1) submitted as electronic supplementary material accompanying the paper, (2) submitted to Biorxiv along with paper preprint at https://www.biorxiv.org/content/ early/2017/11/21/222810, (3) uploaded to Dryad data repository: http://dx.doi.org/10.5061/dryad.k79v6 [56]. Authors{\textquoteright} contributions. K.R. conceived, designed and coordinated the study, measured facial masculinity, performed experiments and statistical analyses and drafted the manuscript; S.S. helped design and coordinate the study, carry out statistical analyses and draft the manuscript; A.G. and D.M. helped coordinate the study, and draft the manuscript; J.H. printed stimulus images and helped coordinate the study and draft the manuscript; D.C. collected the stimulus images and helped design and coordinate the study, carried out statistical analyses and drafted the manuscript. All authors gave final approval for publication. Competing interests. The authors declare that they have no financial or non-financial competing interests. The content of this publication is solely the responsibility of the authors and does not necessarily represent the official views of any of the agencies and organizations that provided research and funding support. Funding. The CPRC is supported by NIH grant number 8 P40 OD012217 from the National Centre for Research Resources (NCRR) and the Office of Research Infrastructure Programs (ORIP). Funding for A.V.G. was provided by the Leakey Foundation, the American Society of Primatologists and the International Primatological Society. Stimuli were produced using funding to J.H. from NYU. Acknowledgements. We thank the staff of the Caribbean Primate Research Centre (CPRC) for their assistance in data collection and logistics. Dr Peter Shaw assisted with the calculation of composite masculinity scores. Sandra Winters helped with image printing at NYU. Field assistance was provided by Severin Mortensen and Maricris Herrera. Funding Information: The CPRC is supported by NIH grant number 8 P40 OD012217 from the National Centre for Research Resources (NCRR) and the Office of Research Infrastructure Programs (ORIP). Funding for A.V.G. was provided by the Leakey Foundation, the American Society of Primatologists and the International Primatological Society. Stimuli were produced using funding to J.H. from NYU. Publisher Copyright: {\textcopyright} 2019 The Authors.",
year = "2019",
doi = "10.1098/rsos.181415",
language = "English (US)",
volume = "6",
journal = "Royal Society Open Science",
issn = "2054-5703",
publisher = "The Royal Society",
number = "1",
}