Saturday, August 11, 2018

Women preferred stoic men who worked even though they were experiencing health problems as long-term mates, disregarding the male's facial symmetry and physique; in short-term mate choice, disregarded stoicism

Female Choice and Male Stoicism. Susan G. Brown, Susan Shirachi, and Danielle Zandbergen. Journal of Evolutionary Medicine,

Abstract: Men consistently report that they are healthier than women but have higher mortality rates. We hypothesized that men were sexually selected to present themselves as healthy to possible mates, according to predictions from health selection theory. The present study tested this theory by contrasting known influences of female mate choice with male's reactions to a health problem (flu symptoms, reaction to vog (air pollution associated with volcanic emissions in the Hawaiian islands) or a headache). Participants viewed three sets of slides contrasting male facial symmetry, physique, and status with stoicism (defined as ignoring a health problem) and were asked to choose which male they preferred as a long-term or a short-term mate. Participants preferred stoic men who worked even though they were experiencing health problems as long-term mates, disregarding the male's facial symmetry and physique. Status also significantly affected long-term mate choice. In short-term mate choice, participants shifted their preferences to symmetrical faces and mesomorphic bodies, signals of attractiveness, disregarding stoicism. In conclusion, our data provide support for health selection theory. Additionally, preventive health measures directed at men should recognize their reluctance to recognize minor health problems and focus on techniques that enhance men's perception of their health symptoms.

Masturbation with a Tool by an Infant Male Chimpanzee

Masturbation with a Tool by an Infant Male Chimpanzee. Michio Nakamura. Graduate School of Science, Kyoto University, Japan.


Here I report a case of “masturbation” with a tool by a wild infant chimpanzee. More accurately, the infant male inserted his erect penis into a wadge discarded by an adult male and performed several thrusts, as if he was copulating with the wadge. The observed “masturbation” did not involve ejaculation, because infant chimpanzees are unable to ejaculate. A similar behavior, i.e., rubbing the penis against a piece of fruit (e.g., orange peel), was reported for infant male orangutans in captivity (Harrison 1962). There are also some reported cases of captive or rehabilitant orangutans and chimpanzees stimulating their own genitals with tools (Dixson 2012).

Masturbation, or self-stimulation of one’s own sexual organs, is common among humans and nowadays is regarded as useful for healthy sexual development (Kaestle & Allen 2011). Various nonhuman primates are also known to masturbate (Thomsen et al. 2003; Dixson 2012; Thomsen & Sommer 2015); therefore, it may be a phylogenetically ancient behavior. However, there are relatively few studies that focus on masturbation among nonhuman primates in the wild (Thomsen & Soltis 2004). Male chimpanzees (Pan troglodytes) are known to stimulate their own penises. Although Goodall (1989) noted that captive chimpanzees sometimes ejaculate by stimulating their own penises, it had not been observed to result in ejaculation in the wild conspecifics at Gombe. Similarly, at Mahale, it is common for males to “fumble with penis,” but without it culminating in ejaculation (Nishida et al. 1999). Such fumbling of penis is done usually by hand (and sometimes by foot), but, thus far, I have found no reports of such penile-stimulating behaviors with tools, at least in wild chimpanzee populations.

Sex and age preferences: Why is age so important in human mating?

Conroy-Beam, D., & Buss, D. M. (2018). Why is age so important in human mating? Evolved age preferences and their influences on multiple mating behaviors. Evolutionary Behavioral Sciences. Advance online publication.

Abstract: Evolutionary theorizing suggests that chronological age, because it is so strongly linked with key reproductive qualities like fertility, should be an exceptionally consequential variable in mate selection. We review voluminous evidence for mate preferences for age and the substantial and varied behavioral sequelae of those preferences. These include (a) in actual marriage decisions, men choose younger wives, and women choose older husbands, on average in all of the dozens of cultures studied; (b) in personal advertisements, men and women seek partners consistent with their expressed age preferences; (c) chronological age determines number of “hits” received in online dating services; (d) the age of potential bride influences the amount of money spent on premarriage customs; (e) men’s mate retention effort, including commitment manipulation, resource provisioning, and intrasexual threats, is significantly predicted by the wife’s age; and (f) chronological age is an important sex-linked cause of divorce. The far-reaching ramifications of age also extend to (g) tactics of intrasexual competition, (h) predictors of mate value discrepancies, (i) victims of sex crimes, and (j) prostitution patterns. Finally, chronological age predicts (k) probability of remarriage, and (l) the age gap between grooms and brides upon remarriage. We synthesize evidence from diverse methods, across different cultures, and over time spans of centuries. Massive converging evidence provides a powerful, yet complex, understanding of the evolutionary importance of age in multiple mating outcomes over the human life span.