Barnaby J. Dixson

Eye-Tracking of Men’s Preferences for Waist-to-Hip Ratio and Breast Size of Women

Studies of human physical traits and mate preferences often use questionnaires asking participants to rate the attractiveness of images. Female waist-to-hip ratio (WHR), breast size, and facial appearance have all been implicated in assessments by men of female attractiveness. However, very little is known about how men make fine-grained visual assessments of such images. We used eye-tracking techniques to measure the numbers of visual fixations, dwell times, and initial fixations made by men who viewed front-posed photographs of the same woman, computer-morphed so as to differ in her WHR (0.7 or 0.9) and breast size (small, medium, or large). Men also rated these images for attractiveness. Results showed that the initial visual fixation (occurring within 200xa0ms from the start of each 5xa0s test) involved either the breasts or the waist. Both these body areas received more first fixations than the face or the lower body (pubic area and legs). Men looked more often and for longer at the breasts, irrespective of the WHR of the images. However, men rated images with an hourglass shape and a slim waist (0.7 WHR) as most attractive, irrespective of breast size. These results provide quantitative data on eye movements that occur during male judgments of the attractiveness of female images, and indicate that assessments of the female hourglass figure probably occur very rapidly.

Human Physique and Sexual Attractiveness in Men and Women: A New Zealand–U.S. Comparative Study

Men and women living in New Zealand and California completed five studies regarding human physique and sexual attractiveness. In Studies 1–3, women rated images of male stimuli and, in Studies 4–5, men rated female stimuli. In Study 1, women in both countries rated mesomorphic (muscular) and average male somatotypes as most attractive, followed by ectomorphic (slim) and endomorphic (heavily built) figures. In Study 2, amount and distribution of masculine trunk hair (chest and abdominal) was altered progressively in a series of front-posed male figures. In both countries, the image lacking any trunk hair was rated as the most attractive, with a steady decline in attractiveness as hirsutism became more pronounced. Study 3 assessed attractiveness of front-posed male figures that varied only in the length of the non-erect penis. Five lengths were presented: The smallest penile size was rated as less attractive than three intermediate sizes. The largest penile size was not the most attractive, but received higher scores than the unaltered and smallest penile size. In Study 4, men rated the attractiveness of back-posed female images varying in waist-to-hip ratio (WHR) (from 0.5 to 1.0). The 0.7 WHR figure was rated more attractive in New Zealand and the 0.6 WHR in California. Study 5 measured the attractiveness of female skin color; men expressed preferences for lighter skinned female figures in New Zealand and California. Results indicate very similar preferences for sexually dimorphic physical traits among men and women of European extraction, living in two culturally and geographically different environments.

Eye Tracking of Men’s Preferences for Female Breast Size and Areola Pigmentation

Sexual selection via male mate choice has often been implicated in the evolution of permanently enlarged breasts in women. While questionnaire studies have shown that men find female breasts visually attractive, there is very little information about how they make such visual judgments. In this study, we used eye-tracking technology to test two hypotheses: (1) that larger breasts should receive the greatest number of visual fixations and longest dwell times, as well as being rated as most attractive; (2) that lightly pigmented areolae, indicative of youth and nubility, should receive most visual attention and be rated as most attractive. Results showed that men rated images with medium-sized or large breasts as significantly more attractive than small breasts. Images with dark and medium areolar pigmentation were rated as more attractive than images with light areolae. However, variations in breast size had no significant effect on eye-tracking measures (initial visual fixations, number of fixations, and dwell times). The majority of initial fixations during eye-tracking tests were on the areolae. However, areolar pigmentation did not affect measures of visual attention. While these results demonstrate that cues indicative of female sexual maturity (large breasts and dark areolae) are more attractive to men, patterns of eye movements did not differ based on breast size or areolar pigmentation. We conclude that areolar pigmentation, as well as breast size, plays a significant role in men’s judgments of female attractiveness. However, fine-grained measures of men’s visual attention to these morphological traits do not correlate, in a simplistic way, with their attractiveness judgments.

Men's Preferences for Women's Breast Morphology in New Zealand, Samoa, and Papua New Guinea

Sexual selection via mate choice may have influenced the evolution of women’s breast morphology. We conducted an image-based questionnaire quantifying and comparing the preferences of men from Papua New Guinea (PNG), Samoa, and New Zealand (NZ) for images of women’s breast size, breast symmetry, areola size, and areolar pigmentation. Results showed that men from PNG preferred larger breasts to a greater extent than men from Samoa and NZ, providing some support for the hypothesis that men from subsistence living cultures have a greater preference for morphological cues indicative of caloric reserves. Symmetrical breasts were most attractive to men in each culture. However, preferences were highest among NZ men, followed by men from Samoa, and were lowest among men from PNG. These results did not support the hypothesis that people living in higher pathogen environments have a greater preference for traits indicative of pathogen resistance and developmental stability. Large areolae were preferred among men from PNG, and to a lesser extent in Samoa, while in NZ men preferred medium-sized areolae. Thus, men’s preferences for women’s areolar size appear to be highly culturally specific. Darkly pigmented areolae were most attractive to men from Samoa and PNG, whereas men from NZ preferred areolae with medium pigmentation. These findings suggest that areolar pigmentation indicative of sexual maturity is preferred by men rather than lighter pigmentation, which may signal that a woman is in the early years of reproductive maturity. This study highlights the importance of cross-cultural research when testing the role of morphological cues in mate choice.

Male Preferences for Female Waist-to-hip Ratio and Body Mass Index in the Highlands of Papua New Guinea

One hundred men, living in three villages in a remote region of the Eastern Highlands of Papua New Guinea were asked to judge the attractiveness of photographs of women who had undergone micrograft surgery to reduce their waist-to-hip ratios (WHRs). Micrograft surgery involves harvesting adipose tissue from the waist and reshaping the buttocks to produce a low WHR and an hourglass female figure. Men consistently chose postoperative photographs as being more attractive than preoperative photographs of the same women. Some women gained, and some lost weight, postoperatively, with resultant changes in body mass index (BMI). However, changes in BMI were not related to mens judgments of attractiveness. These results show that the hourglass female figure is rated as attractive by men living in a remote, indigenous community, and that when controlling for BMI, WHR plays a crucial role in their attractiveness judgments.

Venus Figurines of the European Paleolithic: Symbols of Fertility or Attractiveness?

The earliest known representations of the human female form are the European Paleolithic “Venus figurines,” ranging in age from 23,000 to 25,000 years. We asked participants to rate images of Paleolithic figurines for their attractiveness, age grouping and reproductive status. Attractiveness was positively correlated with measures of the waist-to hip ratio (WHR) of figurines, consistent with the “sexually attractive symbolism” hypothesis. However, most figurines had high WHRs (>1.0) and received low attractiveness scores. Participants rated most figurines as representing middle-aged or young adult women, rather than being adolescent or older (postmenopausal). While some were considered to represent pregnant women, consistent with the “fertility symbol” hypothesis, most were judged as being non-pregnant. Some figurines depict obese, large-breasted women, who are in their mature reproductive years and usually regarded as being of lower attractiveness. At the time these figurines were made, Europe was in the grip of a severe ice age. Obesity and survival into middle age after multiple pregnancies may have been rare in the European Upper Paleolithic. We suggest that depictions of corpulent, middle-aged females were not “Venuses” in any conventional sense. They may, instead, have symbolized the hope for survival and longevity, within well-nourished and reproductively successful communities.

Whatever the Weather: Ambient Temperature Does Not Influence the Proportion of Males Born in New Zealand

Background The proportion of male births has been shown to be over 50% in temperate climates around the world. Given that fluctuations in ambient temperature have previously been shown to affect sex allocation in humans, we examined the hypothesis that ambient temperature predicts fluctuations in the proportion of male births in New Zealand. Methodology/Principal Findings We tested three main hypotheses using time series analyses. Firstly, we used historical annual data in New Zealand spanning 1876–2009 to test for a positive effect of ambient temperature on the proportion of male births. The proportion of males born ranged by 3.17%, from 0.504 to 0.520, but no significant relationship was observed between male birth rates and mean annual temperature in the concurrent or previous years. Secondly, we examined whether changes in annual ambient temperature were negatively related to the proportion of male stillbirths from 1929–2009 and whether the proportion of male stillbirths negatively affected the proportion of male live births. We found no evidence that fewer male stillbirths occurred during warmer concurrent or previous years, though a declining trend in the proportion of male stillbirths was observed throughout the data. Thirdly, we tested whether seasonal ambient temperatures, or deviations from those seasonal patterns, were positively related to the proportion of male births using monthly data from 1980–2009. Patterns of male and female births are seasonal, but very similar throughout the year, resulting in a non-seasonal proportion of male births. However, no cross correlations between proportion of male births and lags of temperature were significant. Conclusions Results showed, across all hypotheses under examination, that ambient temperatures were not related to the proportion of male births or the proportion of male stillbirths in New Zealand. While there is evidence that temperature may influence human sex allocation elsewhere, such effects of temperature are not universal.

Ambient temperature variation does not influence regional proportion of human male births in New Zealand

Abstract Fluctuations in the mean annual ambient temperature have been associated with temporal changes in the proportion of males in total human births. Our aim was to test if changes in mean annual ambient temperature have influenced regional variation in the proportion of males born in New Zealand from 1961 to 2009. We used time-series analyses to test for positive relationships between current or lagged mean annual ambient temperature and the proportion of male births within 13 regions. Only two regions showed a significant effect of either current year or lagged temperature on the proportion of males born, with each showing a decreasing male-bias with temperature (contrary to our hypothesis). Additionally, a meta-analysis revealed that the standardized effect size of temperature on the proportion of male births across regions was negative for both current and previous years, but was not statistically significant. These findings did not support the hypothesis that mean annual ambient temperature affects the proportion of males born.