Sexual Selection and the Evolution of Human Physique

Charles Darwin proposed in The Descent of Man and Selection in Relation to Sex (1871) that traits which improve reproductive success, such as sexually attractive adornments, or weaponry that enhances fighting potential, have been selected for during the course of evolution. The field of evolutionary psychology has revitalized Darwin's hypotheses of sexual selection and human evolution through integrating the fields of anthropology, biology and psychology. In this thesis I investigate the potential for sexual selection to have acted upon sexual dimorphism in body composition and secondary sexual adornments in women and men. In women, body fat accumulation around the hips, buttocks and thighs can be measured using the waist-to-hip ratio (WHR). Female body fat and body weight are critical as energy reserves for gestation, pregnancy and lactation. Female body shape, body weight and breast morphology have been implicated in male judgments of female physical attractiveness. Men from New Zealand (NZ), China, Samoa and the highlands of Papua New Guinea (PNG) rated images of women with low WHRs as most attractive, independent of changes in body weight. In studies of male preferences for female breast morphology, married men from NZ, Samoa and PNG preferred large breasts whereas unmarried men preferred medium-sized breasts. Darkly- and medium-pigmented areolae were preferred in each culture, as were symmetrical breasts. However, male preferences for female areolar size varied considerably across these cultures. Eye-tracking techniques were used to measure attention to morphological traits as men made attractiveness judgments of female images that varied in WHR and breast morphology. In studies using full-length female images that varied in WHR and breast size, men look most often and for longer at the regions of female physique in which fat deposits are greatest (i.e. the breasts followed by the waist). However, attractiveness judgments were driven primarily by WHR rather than breast size. In eye-tracking studies using female torsos as stimuli, men looked most often and for longest at the breasts and areolae, irrespective of differences in breast size and areolar pigmentation. Men rated large and medium size breasts, and medium and darkly pigmented areolae as most attractive. These eye-tracking studies show a possible discordance in male visual attention for morphological traits that appear to drive attractiveness decisions. However, when men were shown full-length images of women posed in back-view as well as in front-view there were significant differences in their viewing patterns. Men spent more time looking at the midriff region of back-posed images than front-posed images and, irrespective of body-pose, rated images with low WHRs as most sexually attractive. Darwin suggested that the human male beard evolved via female choice as a highly attractive secondary sexual adornment. Other authors have proposed that the beard may augment aggressive displays and enhance perceptions of social dominance among males. To test these hypotheses I developed a new questionnaire that integrated facial expressions with the presence or absence of the beard. These questionnaires were administered in NZ and Samoa. The presence of a beard augmented male perceptions of aggressive facial expressions in Samoa and NZ. However, women in these cultures rated faces without beards as more attractive than bearded men. Men and women in both cultures rated bearded men as looking older and as having higher social status. The findings suggest that the beard plays a stronger role in intra-sexual competition rather than inter-sexual mate choice

Mate preferences and choices for facial and body hair in heterosexual women and homosexual men: influence of sex, population, homogamy, and imprinting-like effect

Recent research has reported that male body and facial hair influence women's mate preferences. However, it is not clear whether such preferences are typical for women or for individuals who prefer males as sexual partners. Here we explored body and facial hair in preferred and actual partners among men and women who prefer men as sexual partners. Including homosexual individuals provides a unique opportunity to investigate whether evolved mating psychologies are specific to the sex of the individual or sex of the partner. Based on an online survey of 1577 participants from Brazil and the Czech Republic, we found that, on average, homosexual men preferred hairier stimuli than heterosexual women, supporting past findings that homosexual men have strong preferences for masculine traits. Preferences for facial and body hair appear to be influenced less by sex of the preferred partner than sex of the individual, pointing to a possible sex-specific mating psychology. Further, Brazilians preferred bigger beards than Czechs, which was positively associated with the self-reported amount of beardedness in Brazil, suggesting that familiarity effects underpin cross-cultural differences in preferences for facial hair. Moreover, homosexual men preferred a self-similar degree of beardedness, and Czech women preferred a similar degree of beardedness as their fathers had during their childhood. However, these effects were not associated with the level of facial hair in their actual partners; in general, mate preferences and actual mate choices for facial and body hair differed. Thus, individual differences in some self-reported characteristics, cultural factors, and aspects of personal experience may modulate differences in preferences for masculine traits

The Psychological Science Accelerator: Advancing Psychology Through a Distributed Collaborative Network

Source at https://doi.org/10.1177/2515245918797607.Concerns about the veracity of psychological research have been growing. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions or replicate prior research in large, diverse samples. The PSA’s mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time limited), efficient (in that structures and principles are reused for different projects), decentralized, diverse (in both subjects and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside the network). The PSA and other approaches to crowdsourced psychological science will advance understanding of mental processes and behaviors by enabling rigorous research and systematic examination of its generalizability

The psychological science accelerator’s COVID-19 rapid-response dataset

In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

The Psychological Science Accelerator’s COVID-19 rapid-response dataset

In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic.

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

Sexual Selection and the Evolution of Human Physique

Charles Darwin proposed in The Descent of Man and Selection in Relation to Sex (1871) that traits which improve reproductive success, such as sexually attractive adornments, or weaponry that enhances fighting potential, have been selected for during the course of evolution. The field of evolutionary psychology has revitalized Darwin's hypotheses of sexual selection and human evolution through integrating the fields of anthropology, biology and psychology. In this thesis I investigate the potential for sexual selection to have acted upon sexual dimorphism in body composition and secondary sexual adornments in women and men. In women, body fat accumulation around the hips, buttocks and thighs can be measured using the waist-to-hip ratio (WHR). Female body fat and body weight are critical as energy reserves for gestation, pregnancy and lactation. Female body shape, body weight and breast morphology have been implicated in male judgments of female physical attractiveness. Men from New Zealand (NZ), China, Samoa and the highlands of Papua New Guinea (PNG) rated images of women with low WHRs as most attractive, independent of changes in body weight. In studies of male preferences for female breast morphology, married men from NZ, Samoa and PNG preferred large breasts whereas unmarried men preferred medium-sized breasts. Darkly- and medium-pigmented areolae were preferred in each culture, as were symmetrical breasts. However, male preferences for female areolar size varied considerably across these cultures. Eye-tracking techniques were used to measure attention to morphological traits as men made attractiveness judgments of female images that varied in WHR and breast morphology. In studies using full-length female images that varied in WHR and breast size, men look most often and for longer at the regions of female physique in which fat deposits are greatest (i.e. the breasts followed by the waist). However, attractiveness judgments were driven primarily by WHR rather than breast size. In eye-tracking studies using female torsos as stimuli, men looked most often and for longest at the breasts and areolae, irrespective of differences in breast size and areolar pigmentation. Men rated large and medium size breasts, and medium and darkly pigmented areolae as most attractive. These eye-tracking studies show a possible discordance in male visual attention for morphological traits that appear to drive attractiveness decisions. However, when men were shown full-length images of women posed in back-view as well as in front-view there were significant differences in their viewing patterns. Men spent more time looking at the midriff region of back-posed images than front-posed images and, irrespective of body-pose, rated images with low WHRs as most sexually attractive. Darwin suggested that the human male beard evolved via female choice as a highly attractive secondary sexual adornment. Other authors have proposed that the beard may augment aggressive displays and enhance perceptions of social dominance among males. To test these hypotheses I developed a new questionnaire that integrated facial expressions with the presence or absence of the beard. These questionnaires were administered in NZ and Samoa. The presence of a beard augmented male perceptions of aggressive facial expressions in Samoa and NZ. However, women in these cultures rated faces without beards as more attractive than bearded men. Men and women in both cultures rated bearded men as looking older and as having higher social status. The findings suggest that the beard plays a stronger role in intra-sexual competition rather than inter-sexual mate choice