Selective attention toward female secondary sexual color in male rhesus macaques

Abstract

Pink-to-red anogenital and facial sexual skin occurs in females of many primate species. Since female sexual skin color varies with reproductive state, it has long been assumed that color acts to stimulate male sexual interest. Although there is supportive evidence for this as regards anogenital skin, it is unclear whether this is also the case for facial sexual skin. In this study we experimentally manipulated digital facial and hindquarter images of female rhesus macaques (Macaca mulatta) for color within the natural range of variation. The images were presented to adult male conspecifics to assess whether the males exhibited visual preferences for red vs. non-red female coloration, and whether preferences varied with anatomical region. The males displayed significantly longer gaze durations in response to reddened versions of female hindquarters, but not to reddened versions of faces. This suggests that female facial coloration may serve an alternative purpose to that of attracting males, and that the signal function of sexual skin and the intended recipients may vary across anatomical regions.

Spontaneous voice–face identity matching by rhesus monkeys for familiar conspecifics and humans

“…This congruence accounts for the intrinsic variability in looking times across faces that may bias the time allocated to each of the two images. Looking behavior can be influenced by factors such as dominance or sexual coloration of the pictured individuals (9,12). We confirmed that our pictures yielded different looking times with a one-way analysis of variance (ANOVA) with face identity as a factor (Table S1 and Fig.…”

“…In comparison with discrimination, individual recognition requires an additional associative level that allows retrieval of information belonging to a specific individual. In rhesus monkeys, coarse recognition processes such as of their own species, kin, gender, reproductive status, or hierarchy are well documented (2,(7)(8)(9)(10)(11)(12). However, these rudimentary recognition abilities fail to account for some sophisticated behaviors that are observed in rhesus macaques' societies.…”

Monkey visual behavior falls into the uncanny valley

“…Thus, these data demonstrate that the uncanny valley effect is not unique to humans, and that evolutionary hypotheses regarding its origins are tenable. For example, although we cannot determine whether our monkey subjects find the realistic synthetic faces less attractive than real faces, we do know that many of the facial features that drive attractiveness in humans, such as facial coloration, may also influence the visual preferences of monkeys (13)(14)(15)(16). What cannot be discerned in our experiment is whether the monkeys are experiencing disgust or fear (or aversion more generally) when they look at the realistic synthetic faces.…”

Color in competition contexts in non-human animals

“…in Vandenburgh, 1965), a recent study found no evidence that red coloration is linked to rank or to androgen levels during the mating season (Higham et al, 2013). No experimental studies have yet been published that examine male-male relationships in relation to red in rhesus macaques, although adult males do attend to female red coloration (Higham et al, 2011;Waitt et al, 2006). Males also attend to red more generally: adult males were more likely to choose food from an experimenter wearing green than one wearing red, regardless of the sex of the experimenter, and were also more likely to take food from a male experimenter wearing blue than from a female experimenter wearing red (here the sex effect was not tested) (Khan, Levine, Dobson, & Kralik, 2011).…”