Findings

Attractiveness and Sex Differences

Kevin Lewis

May 02, 2010

Zoonotic and Non-Zoonotic Diseases in Relation to Human Personality and Societal Values: Support for the Parasite-Stress Model

Randy Thornhill, Corey Fincher, Damian Murray & Mark Schaller
Evolutionary Psychology, April 2010, Pages 151-169

Abstract:
The parasite-stress model of human sociality proposes that humans' ontogenetic experiences with infectious diseases as well as their evolutionary historical interactions with these diseases exert causal influences on human psychology and social behavior. This model has been supported by cross-national relationships between parasite prevalence and human personality traits, and between parasite prevalence and societal values. Importantly, the parasite-stress model emphasizes the causal role of non-zoonotic parasites (which have the capacity for human-to-human transmission), rather than zoonotic parasites (which do not), but previous studies failed to distinguish between these conceptually distinct cate-gories. The present investigation directly tested the differential predictive effects of zoonotic and non-zoonotic (both human-specific and multihost) parasite prevalence on personality traits and societal values. Supporting the parasite-stress model, cross-national differences in personality traits (unrestricted sexuality, extraversion, openness to experiences) and in societal values (individualism, collectivism, gender equality, democratiza-tion) are predicted specifically by non-zoonotic parasite prevalence.

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Captured by True Crime: Why Are Women Drawn to Tales of Rape, Murder, and Serial Killers?

Amanda Vicary & Chris Fraley
Social Psychological and Personality Science, January 2010, Pages 81-86

Abstract:
The true crime genre, which consists of nonfiction books based on gruesome topics such as rape and murder, has amassed an extensive audience. Many people might assume that men, being the more aggressive sex, would be most likely to find such gory topics interesting. But a perusal of published reader reviews suggests that women enjoy these kinds of books more so than do men. The purpose of this research was to shed light on this apparent paradox. In Studies 1 and 2, the authors conducted a study of reader reviews and a study of book choices that demonstrated that, in fact, women are more drawn to true crime stories whereas men are more attracted to other violent genres. In Studies 3 to 5, the authors manipulated various characteristics of true crime stories to determine which features women find appealing. The authors discuss the findings in light of contemporary evolutionary perspectives on aggression and murder.

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Up or Down? A Male Economist's Manifesto on the Toilet Seat Etiquette

Jay Choi
Economic Inquiry, forthcoming

Abstract:
This paper develops an economic analysis of the toilet seat etiquette. I investigate whether there is any efficiency justification for the presumption that men should leave the toilet seat down after use. I find that the "down rule" is inefficient unless there is a large asymmetry in the inconvenience costs of shifting the position of the toilet seat across genders. I show that the "selfish" or the "status quo" rule that leaves the toilet seat in the position used dominates the down rule in a wide range of parameter spaces including the case where the inconvenience costs are the same.

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Physical Contact and Financial Risk Taking

Jonathan Levav & Jennifer Argo
Psychological Science, forthcoming

Abstract:
We show that minimal physical contact can increase people's sense of security and consequently lead them to increased risk-taking behavior. In three experiments, with both hypothetical and real payoffs, a female experimenter's light, comforting pat on the shoulder led participants to greater financial risk taking. Further, this effect was both mediated and moderated by feelings of security in both male and female participants. Finally, we established the boundary conditions for the impact of physical contact on risk-taking behaviors by demonstrating that the effect does not occur when the touching is performed by a male and is attenuated when the touch consists of a handshake. The results suggest that subtle physical contact can be strongly influential in decision making and the willingness to accept risk.

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Contact with attractive women affects the release of cortisol in men

Leander van der Meij, Abraham Buunk & Alicia Salvador
Hormones and Behavior, forthcoming

Abstract:
Previous studies have shown that situations relevant for human mating can affect the levels of many hormones. This study focused on the hypothalamus-pituitary-adrenal axis by measuring salivary cortisol levels in 84 young men prior to and after a period of short social contact with a woman or man. Results showed that after contact with another man the cortisol levels of the participants declined according to the circadian release pattern of cortisol. However, cortisol levels in men declined less when they had contact with a woman. Furthermore, cortisol levels of men increased when they perceived the woman with whom they had contact as attractive. Our findings provide indirect evidence for the role of the hypothalamus-pituitary-adrenal axis in human courtship. During social contact with attractive women, moderate increases in cortisol levels may reflect apprehension over an opportunity for courtship.

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Sex differences in mushroom gathering: Men expend more energy to obtain equivalent benefits

Luis Pacheco-Cobos, Marcos Rosetti, Cecilia Cuatianquiz & Robyn Hudson
Evolution and Human Behavior, forthcoming

Abstract:
Some of the strongest evidence for sex differences in human cognition relate to spatial abilities, with men traditionally reported to outperform women. Recently, however, such differences have been shown to be task dependent. Supporting the argument that a critical factor selecting for sex differences in spatial abilities during human evolution is likely to have been the division of labor during the Pleistocene, evidence is accumulating that women excel on tasks appropriate to gathering immobile plant resources, while men excel on tasks appropriate to hunting mobile, unpredictable prey. Most research, with the exception of some recent experimental field studies, has been conducted in the laboratory, with little information available on how men and women actually forage under natural conditions. In a first study, we GPS-tracked the foraging pathways of 21 pairs of men and women from an indigenous Mexican community searching for mushrooms in a natural environment. Measures of costs, benefits and general search efficiency were analyzed and related to differences between the two sexes in foraging patterns. Although men and women collected similar quantities of mushrooms, men did so at significantly higher cost. They traveled further, to greater altitudes, and had higher mean heart rates and energy expenditure (kcal). They also collected fewer species and visited fewer collection sites. These findings are consistent with arguments in the literature that differences in spatial ability between the sexes are domain dependent, with women performing better and more readily adopting search strategies appropriate to a gathering lifestyle than men.

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Male axillary extracts modify the affinity of the platelet serotonin transporter and impulsiveness in women

Donatella Marazziti, Irene Masala, Stefano Baroni, Margherita Polini, Gabriele Massimetti, Gino Giannaccini, Laura Betti, Paola Italiani, Laura Fabbrini, Carolina Caglieresi, Cecilia Moschini, Domenico Canale, Antonio Lucacchini & Mauro Mauri
Physiology & Behavior, forthcoming

Abstract:
The presence of functional pheromones in axillary extracts in humans is still matter of debate. Scattered data suggest that unidentified human axillary compounds with pheromonal activity may influence mood and this may occur, perhaps, through the modulation of the serotonin (5-HT) system that has been linked to mood by several findings. Therefore, the aim of this study was to assess the possible changes of a peripheral marker of the 5-HT system, i.e., the platelet 5HT transporter, and of some psychological tests, in a group of women who were exposed to male axillary extracts (group 1). A matched group of women who underwent an exposure to a neutral solution, were used as control subjects (group 2). The 5-HT transporter was evaluated by means of the specific binding of 3H-paroxetine (3H-Par) to platelet membranes, as well as by means of 3H-5-HT reuptake in whole platelets, at baseline (T0) and 1 h after the stimulation (T1). The following tests were used: the "Experiences in Close Relationships" questionnaire (ECR), the latest version of the Barratt Impulsiveness Scale (BIS-11) and the Structured Clinical Interview for Mood Spectrum, self-reported version. The dissociation constant (Kd) of 3H-Par binding showed a significant decrease at T1 only in the women exposed to male axillary extracts, as compared with baseline values, while the Bmax and 3H-5-HT reuptake parameters did not show any change in both groups. The correlation analyses showed that at T0, the Kd values correlated significantly and positively with the factor of motor impulsiveness in all subjects. Two factors of the BIS-11, in particular, the attentional and the motor impulsiveness were significantly lower at T1 in the group 1. Further, at T1 and still in the group 1, a significant and positive correlation was measured between the Kd values and two ECR attachment styles, the secure and preoccupied, as well as with the ECR anxiety scale. Taken together, these findings suggest that the application of male axillary extracts to women may modify the affinity of their platelet 5-HT transporter, as well as of some impulsiveness and romantic attachment characteristics. The substances responsible for this effect remain to be identified.

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Evolved foraging psychology underlies sex differences in shopping experiences and behaviors

Daniel Kruger & Dreyson Byker
Journal of Social, Evolutionary, and Cultural Psychology, December 2009, Pages 328-342

Abstract:
This study documents that men and women experience and perform consumer shopping differently, and in ways consistent with adaptations to the sexually dimorphic foraging strategies utilized during recent human evolution. There is an abundant literature on sex differences in spatial abilities and object location that follow from the specific navigational strategies associated with hunting and gathering in the ancestral environment. In addition to sex differences in navigational strategies, the unique features of hunting and gathering may have influenced other aspects of foraging psychology that underlie sex differences in modern male and female shopping experiences and behaviors. Scales were developed to assess several aspects of shopping psychology that may be based on sexually differentiated ancestral adaptations. Results generally confirmed the predicted directions of sex differences. Compared to men, women relied more on object oriented navigation strategies and scored higher on skills and behaviors associated with gathering, the degree to which shopping is seen as recreational, the degree to which shopping is a social activity, and the tendency to see new locations as opportunities for shopping. Men scored higher on skills and behaviors thought to be associated with hunting. Most effect sizes were moderate or strong. These results suggest that shopping experiences and behaviors are influenced by sexually divergent adaptations for gathering and hunting.

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Signals of Genetic Quality and Maternal Investment Capacity: The Dynamic Effects of Fluctuating Asymmetry and Waist-to-Hip Ratio on Men's Ratings of Women's Attractiveness

Helen Perilloux, Gregory Webster & Steven Gaulin
Social Psychological and Personality Science, January 2010, Pages 34-42

Abstract:
Fluctuating asymmetry (FA) and waist-to-hip ratio (WHR) are frequently studied physical attractiveness variables in social and evolutionary psychology. FA represents deviations in bilateral symmetry - differences between left and right body parts. WHR is the ratio of the smallest part of the waist to the largest part of the hips. Although FA and WHR are important mate preference criteria, research has not examined their joint influence on attraction. Thus, 140 heterosexual male undergraduates ranked - and 118 rated - the attractiveness of 10 photographs of rear-facing nude women. Women's FA and WHR were negatively related to attractiveness separately, after controlling for each other and after controlling for body mass index (BMI). An FA x WHR interaction emerged, such that men's preferences for lower WHRs increased as FA decreased, even after controlling for BMI. FA and WHR affected attractiveness in ways consistent with the information they carry and its likely effects on offspring quality.

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Cross-cultural consensus for waist-hip ratio and women's attractiveness

Devendra Singh, B.J. Dixson, T.S. Jessop, B. Morgand & A.F. Dixson
Evolution and Human Behavior, May 2010, Pages 176-181

Abstract:
In women of reproductive age, a gynoid body fat distribution as measured by the size of waist-hip ratio (WHR) is a reliable indicator of their sex hormone profile, greater success in pregnancy and less risk for major diseases. According to evolutionary mate selection theory, such indicators of health and fertility should be judged as attractive. Previous research has confirmed this prediction. In this current research, we use the same stimulus for diverse racial groups (Bakossiland, Cameroon, Africa; Komodo Island, Indonesia; Samoa; and New Zealand) to examine the universality of relationships between WHR and attractiveness. As WHR is positively correlated with body mass index (BMI), we controlled BMI by using photographs of women who have gone through micrograft surgery for cosmetic reasons. Results show that in each culture participants selected women with low WHR as attractive, regardless of increases or decreases in BMI. This cross-cultural consensus suggests that the link between WHR and female attractiveness is due to adaptation shaped by the selection process.


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