Tamsin K. Saxton

Evidence that androstadienone, a putative human chemosignal, modulates women's attributions of men's attractiveness

Considerable research effort has focused on whether specific compounds found within human body odor influence the behavior or physiology of other individuals. The most intensively studied is 4,16-androstadien-3-one, a chemical which is known to modulate mood and have activational effects in the sympathetic nervous system in a context-dependent manner, but whose action in mate-choice contexts remains largely untested. Here we present evidence that this androgen steroid may modulate womens judgments of mens attractiveness in an ecologically valid context. We tested the effects of androstadienone at a speed-dating event in which men and women interacted in a series of brief dyadic encounters. Men were rated more attractive when assessed by women who had been exposed to androstadienone, an effect that was seen in two out of three studies. The results suggest that androstadienone can influence womens attraction to men, and also that research into the modulatory effects of androstadienone should be made within ecologically valid contexts.

Women's preferences for masculinity in male faces are highest during reproductive age range and lower around puberty and post-menopause

Masculinity in male faces is thought to be a sign of mate quality and is associated with measures of long-term health. Previous studies have demonstrated that womens masculinity preferences change across the menstrual cycle with women preferring more masculine men during phases of the menstrual cycle where fertility is highest (i.e. the late follicular phase). Given the hormonal correlates of such preferences and that these hormones change across the life span, we tested for differences in female masculinity preferences at different ages. We compared the masculinity preferences of peri-pubescent girls and young adult women (Study 1), circum-menopausal women reporting to either be pre- or post-menopause (Study 2), and a large sample of women across a wide range of ages (Study 3). In all three studies, preferences for masculinity in male faces were highest in women who were at a reproductively active age. Preferences for masculinity were lower when females were peri-pubescent, post-menopausal, or at ages corresponding to these groups. These data support the notion that masculinity in male faces is an important trait for reproductively relevant mate choice decisions. These data also highlight a shift in female visual preferences for men that is associated with important stages of the lifespan. Visual preferences appear to track important hormonal changes associated with age; as women pass puberty their preferences shift towards facial traits associated with mate quality and as women undergo menopause their preferences for such facial traits decrease. Overall, these results demonstrate the important role of reproductive status and support the notion that preferences for male faces are tied to reproductively relevant hormones.

Current issues in the study of androstenes in human chemosignaling.

We review research on the 16-androstenes and their special claim, born originally of the finding that androstenes function as boar pheromones, to be human chemosignals. Microbial fauna in human axillae act upon the 16-androstenes to produce odorous volatiles. Both individual variation and sex differences in perception of these odors suggest that they may play a role in mediating social behavior, and there is now much evidence that they modulate changes in interpersonal perception, and individual mood, behavior, and physiology. Many of these changes are sensitive to the context in which the compounds are experienced. However, many key outstanding questions remain. These include identification of the key active compounds, better quantification of naturally occurring concentrations and understanding how experimentally administered concentrations elicit realistic effects, and elucidation of individual differences (e.g., sex differences) in production rates. Until such issues are addressed, the question of whether the androstenes play a special role in human interactions will remain unresolved.

Face, body and speech cues independently predict judgments of attractiveness

Abstract Research on human attraction frequently makes use of single-modality stimuli such as neutral-expression facial photographs as proxy indicators of an individuals attractiveness. However, we know little about how judgments of these single-modality stimuli correspond to judgments of stimuli that incorporate multi-modal cues of face, body and speech. In the present study, ratings of attractiveness judged from videos of participants introducing themselves were independently predicted by judgments of the participants facial attractiveness (a neutral-expression facial photograph masked to conceal the hairstyle), body attractiveness (a photograph of the upper body), and speech attractiveness (the soundtrack to the video). We also found that ratings of the face, body and speech were positively related to each other. Our results support the assumption that the single-modality stimuli used in much attractiveness research are valid proxy indicators of overall attractiveness in ecologically valid contexts, ...

Body odor quality predicts behavioral attractiveness in humans

Growing effort is being made to understand how different attractive physical traits co-vary within individuals, partly because this might indicate an underlying index of genetic quality. In humans, attention has focused on potential markers of quality such as facial attractiveness, axillary odor quality, the second-to-fourth digit (2D:4D) ratio and body mass index (BMI). Here we extend this approach to include visually-assessed kinesic cues (nonverbal behavior linked to movement) which are statistically independent of structural physical traits. The utility of such kinesic cues in mate assessment is controversial, particularly during everyday conversational contexts, as they could be unreliable and susceptible to deception. However, we show here that the attractiveness of nonverbal behavior, in 20 male participants, is predicted by perceived quality of their axillary body odor. This finding indicates covariation between two desirable traits in different sensory modalities. Depending on two different rating contexts (either a simple attractiveness rating or a rating for long-term partners by 10 female raters not using hormonal contraception), we also found significant relationships between perceived attractiveness of nonverbal behavior and BMI, and between axillary odor ratings and 2D:4D ratio. Axillary odor pleasantness was the single attribute that consistently predicted attractiveness of nonverbal behavior. Our results demonstrate that nonverbal kinesic cues could reliably reveal mate quality, at least in males, and could corroborate and contribute to mate assessment based on other physical traits.

A LONGITUDINAL STUDY OF ADOLESCENTS' JUDGMENTS OF THE ATTRACTIVENESS OF FACIAL SYMMETRY, AVERAGENESS AND SEXUAL DIMORPHISM

Abstract Adolescents have been found to differ by age in their attraction to facial symmetry, averageness, and sexual dimorphism. However, it has not been demonstrated that attraction to these facial characters changes over time as a consequence of age-linked development. We aimed to extend previous cross-sectional findings by examining whether facial attractiveness judgments change over time during adolescence as a consequence of increasing age, in a within-subjects study of two cohorts of adolescents aged 11–16. Consistent with previous findings, we find that adolescents (often particularly females) judged faces with increased averageness, symmetry and femininity to be more attractive than original, asymmetric and masculine faces, respectively. However, we do not find longitudinal changes in face preference judgments across the course of a year, leading us to question the extent to which some of the previously reported differences in facial attractiveness judgments between younger and older adolescents ...

Changes in women’s facial skin color over the ovulatory cycle are not detectable by the human visual system

Human ovulation is not advertised, as it is in several primate species, by conspicuous sexual swellings. However, there is increasing evidence that the attractiveness of women’s body odor, voice, and facial appearance peak during the fertile phase of their ovulatory cycle. Cycle effects on facial attractiveness may be underpinned by changes in facial skin color, but it is not clear if skin color varies cyclically in humans or if any changes are detectable. To test these questions we photographed women daily for at least one cycle. Changes in facial skin redness and luminance were then quantified by mapping the digital images to human long, medium, and shortwave visual receptors. We find cyclic variation in skin redness, but not luminance. Redness decreases rapidly after menstrual onset, increases in the days before ovulation, and remains high through the luteal phase. However, we also show that this variation is unlikely to be detectable by the human visual system. We conclude that changes in skin color are not responsible for the effects of the ovulatory cycle on women’s attractiveness.

A lover or a fighter? Opposing sexual selection pressures on men’s vocal pitch and facial hair

Lay Summary Men’s optimum masculinity depends on whether they want to attract partners or compete with rivals. We found that men’s voice pitch was most attractive around 1.5 standard deviations lower than average, whereas facial hair growth did not consistently affect attractiveness. In contrast, men were perceived ever more dominant with lower voices and more facial hair. Sexual selection consists of both attracting mates and competing against rivals, but here selection pressures might oppose each other somewhat.

Sex Differences in Olfactory Behavior in Namibian and Czech Children

Sex differences in olfaction are well-established, but explanations for those sex differences remain incomplete. One contributing factor could be individual- or cultural-level differences in exposure to odors. We tested whether frequent engagement with common sources of domestic odors (cooking, domestic animals, siblings) was linked to individual differences in olfactory reactivity and awareness among children in southern Namibia and also compared study populations in southern Namibia and the Czech Republic using the established Children’s Olfactory Behavior in Everyday Life (COBEL) questionnaire. We did not find any effects of engagement with odor sources on olfactory behavior, but our results were consistent with usual olfactory sex differences in that girls scored higher than boys in measures of olfactory reactivity and awareness. Further, among the Czech children (but not among the Namibian children), odor identification abilities were positively linked to COBEL scores. Our data contribute to the literature that finds that sex differences in olfactory awareness are apparent across a diverse range of cultures and age groups.

Ecological Validity in the Study of Human Pheromones

Several constituents of human axillary secretions have been proposed as candidate human pheromones, but their influence on human behaviour remains controversial. Here we briefly review the literature on the behavioural effects of candidate compounds, noting that inconsistencies in findings could be due in part to the variation in experimental context and potential lack of ecological validity. We also report results of a pilot study which attempts to overcome these limitations in an ecologically-valid experimental paradigm: a speed-dating event. We tested the effects of 4,16-androstadien-3-one within a single speed-dating evening with 25 female and 22 male participants. We found a significant effect of androstadienone on female judgments of male attractiveness, which is consistent with the proposal that androstadienone could act as a modulatory pheromone in humans.