A greater decline in female facial attractiveness during middle age reflects women’s loss of reproductive value

Facial attractiveness represents an important component of an individual’s overall attractiveness as a potential mating partner. Perceptions of facial attractiveness are expected to vary with age-related changes in health, reproductive value, and power. In this study, we investigated perceptions of facial attractiveness, power, and personality in two groups of women of pre- and post-menopausal ages (35–50 years and 51–65 years, respectively) and two corresponding groups of men. We tested three hypotheses: (1) that perceived facial attractiveness would be lower for older than for younger men and women; (2) that the age-related reduction in facial attractiveness would be greater for women than for men; and (3) that for men, there would be a larger increase in perceived power at older ages. Eighty facial stimuli were rated by 60 (30 male, 30 female) middle-aged women and men using online surveys. Our three main hypotheses were supported by the data. Consistent with sex differences in mating strategies, the greater age-related decline in female facial attractiveness was driven by male respondents, while the greater age-related increase in male perceived power was driven by female respondents. In addition, we found evidence that some personality ratings were correlated with perceived attractiveness and power ratings. The results of this study are consistent with evolutionary theory and with previous research showing that faces can provide important information about characteristics that men and women value in a potential mating partner such as their health, reproductive value, and power or possession of resources

Dynamic simulation of forest management normative scenarios : the case of timber plantations in the southern Chile

International audienceAccounting for spatial issues (spatially explicit simulation, geographical amenities and advantages of land use 10 and cover changes, etc.) to build prospective scenarios is a crucial issue for better assessment of possible impacts on the environment. Such spatialized scenarios and their implications allow societies to reduce the uncertainty of the future by exploring various strategies for land use changes. Despite the wide diversity in existing scenario-building techniques, two different approaches can be distinguished (exploratory vs. normative) for their methodological implications. The originality in this study comes from the use of a relevant exploratory 15 (dynamic) approach to map normative scenarios which, in most cases, are represented throughout the combination of narratives and synchronic land use and cover maps. The objective of the article is to apply this dynamic exploratory simulation approach to spatialize normative scenarios within the framework of forest management in southern Chile. In the results, two contrasting images of the future are compared, with the preservation of native forests on one hand and the spread of exotic timber plantations on the other

Experimental evidence that female rhesus macaques (Macaca mulatta) perceive variation in male facial masculinity

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. However, whether conspecifics pay attention to facial masculinity has only been assessed in humans. Here, working with 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 more masculine and one more feminine – and recorded their looking behaviour. Females looked toward the masculine face longer than 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

Effect of Mating Activity and Dominance Rank on Male Masturbation Among Free-Ranging Male Rhesus Macaques

Abstract The adaptive function of male masturbation is still poorly understood, despite its high prevalence in humans and other animals. In non-human primates, male masturbation is most frequent among anthropoid monkeys and apes living in multimale-multifemale groups with a promiscuous mating system. In these species, male masturbation may be a non-functional by-product of high sexual arousal or be adaptive by providing advantages in terms of sperm competition or by decreasing the risk of sexually transmitted infections. We investigated the possible functional significance of male masturbation using behavioral data collected on 21 free-ranging male rhesus macaques (Macaca mulatta) at the peak of the mating season. We found some evidence that masturbation is linked to low mating opportunities: regardless of rank, males were most likely to be observed masturbating on days in which they were not observed mating, and lower-ranking males mated less and tended to masturbate more frequently than higher-ranking males. These results echo the findings obtained for two other species of macaques, but contrast those obtained in red colobus monkeys (Procolobus badius) and Cape ground squirrels (Xerus inauris). Interestingly, however, male masturbation events ended with ejaculation in only 15% of the observed masturbation time, suggesting that new hypotheses are needed to explain masturbation in this species. More studies are needed to establish whether male masturbation is adaptive and whether it serves similar or different functions in different sexually promiscuous species

Ethnicity-Related Variation in Sexual Promiscuity, Relationship Status, and Testosterone Levels in Men

The purpose of this study was to investigate potential ethnicity-related variation in men's relationship status, sexual promiscuity, and testosterone levels. Data from two ethnically diverse subject populations were used. The first dataset included 302 male graduate students (age range: 23-36 years; M ϭ 28); the second dataset consisted of 77 male undergraduate and graduate students (age range: 18 -38 years; M ϭ 23). For both, we collected information on ethnicity (European American, African American, Hispanic, or Asian American), relationship status (single, in a short-term or long-term relationship, or married), and sexual promiscuity (number of lifetime sexual partners, number of one-night stands, extrapair sexual activity), in addition to measuring salivary testosterone concentrations. In both datasets testosterone levels were significantly higher in single men than in men in relationships but this difference was reversed in men of Asian American ethnicity. Asian American men had the lowest number of sexual partners, one-night stands, and extrapair sexual activity across ethnic groups. Moreover, among Asian Americans, men in relationships had a higher average number of sexual partners than single men. Our results indicate that to understand the association between relationship status and testosterone levels in men, ethnicity-related variation in sexual activity in single men and men in relationships must be taken into consideration