“The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness?”
1999 Study by Randy Thornhill and Steven W. Gangestad
This study investigates the potential role of body scent as a signal of genetic and phenotypic quality in human mate selection. It explores how olfactory cues, particularly pheromones, influence sexual attraction and mate choice. Specifically, the study examines the relationship between body symmetry, scent attractiveness, and menstrual cycle variation in women’s preferences.
Background and Rationale
Chemical Candidates Discussed
The study discusses androstenone and androstenol as potential chemical candidates for human sex pheromones, with a particular focus on their role in signaling body symmetry.
Implications and Conclusions
The study suggests that the scent of symmetry in men may act as an honest signal of genetic and phenotypic quality. These findings support the idea that women have evolved preferences for mates with superior genes, and that olfactory cues play a significant role in mate selection.
1999 Study by Randy Thornhill and Steven W. Gangestad
This study investigates the potential role of body scent as a signal of genetic and phenotypic quality in human mate selection. It explores how olfactory cues, particularly pheromones, influence sexual attraction and mate choice. Specifically, the study examines the relationship between body symmetry, scent attractiveness, and menstrual cycle variation in women’s preferences.
Background and Rationale
- Olfactory Cues in Mate Selection: Previous research indicates that body scent significantly impacts sexual interest, with women being more affected by olfactory cues than men. Women view scent as an important factor in mate selection and sexual arousal.
- Menstrual Cycle Variation: Women’s attraction to androstenone (a component of human scent) fluctuates across the menstrual cycle, with more favorable ratings near ovulation. Sensitivity to androstenol, a precursor of androstenone, also increases before ovulation.
- Good-Genes Sexual Selection: The study operates within the framework of good-genes sexual selection, hypothesizing that women prefer mates with genes that enhance offspring fitness, especially during their fertile phase.
- Fluctuating Asymmetry (FA) as a Marker: FA refers to small, random deviations from perfect bilateral symmetry and is viewed as a marker of genetic and environmental stress resistance during development. Low FA is linked to better fitness, including health, longevity, and mating success.
- Parental Investment Theory: The article mentions parental investment theory to explain why symmetry appears to have a stronger effect on male attractiveness. Because males typically invest less in offspring, sexual selection is expected to be stronger in males.
- Women, especially those not using hormonal contraceptives, will find the body scent of men with greater body symmetry more attractive during the high-fertility phase of their menstrual cycle.
- Facial attractiveness will predict body scent attractiveness to the opposite sex.
- Men will not prefer the scent of symmetrical women.
- Participants: The study involved 80 men (mean age 20.4) and 82 women (mean age 22.3), all recruited from an introductory psychology course. Only women not using hormonal contraceptives were included.
- Symmetry Measurement: Researchers measured ten bilateral body traits (e.g., ear length/width, elbow width, wrist width, ankle width, etc.) using digital calipers. Facial photographs were also taken.
- Scent Collection: Participants wore clean, unscented cotton T-shirts for two nights while sleeping. Strict guidelines were set to minimize external influences on body scent, including using unscented soaps, avoiding scented products, and abstaining from certain foods, alcohol, drugs, tobacco, and sexual activity.
- Scent Evaluation: Participants returned the T-shirts, which were then evaluated for scent attractiveness. The method of scent evaluation, though not explicitly detailed, involved assessing attractiveness by the opposite sex.
- Replication of Previous Findings: The study confirmed the previous finding that women not using hormonal contraceptives rate the scent of more symmetrical men as more attractive during their fertile phase.
- Control for Confounding Variables: The study controlled for factors such as men’s hygiene practices, addressing limitations from earlier research.
- No Preference for Symmetrical Women’s Scent: Contrary to the hypothesis, the study found no evidence that men prefer the scent of symmetrical women.
- Facial Attractiveness and Scent: The study found that facial attractiveness appears to predict body scent attractiveness to the opposite sex.
Chemical Candidates Discussed
The study discusses androstenone and androstenol as potential chemical candidates for human sex pheromones, with a particular focus on their role in signaling body symmetry.
Implications and Conclusions
The study suggests that the scent of symmetry in men may act as an honest signal of genetic and phenotypic quality. These findings support the idea that women have evolved preferences for mates with superior genes, and that olfactory cues play a significant role in mate selection.
