Body Odour and Sexual Attraction in Humans

This entry was written by Natasha Black as part of a project done in BIAN 2133 ‘Human Reproductive Strategies’ at The Australian National University in 2019 Semester 2.

Introduction:

Body odour, an olfactory cue, is an important signal that is used by brain when determining if a potential mate is sexually attractive or not. Body odour is able to indicate the level of fertility in a female that can be interpreted by both males and other females, the genetic compatibility of a mate especially in relation to the immune system and even a potential mate’s diet which can indicate good health and available resources. This makes body odour an important reproductive strategy in terms of choosing a mate which is demonstrated by less attraction in body odour in homosexual males.

Main Text:

In females their level of fertility is communicated through their body odour that can be detected by both males and females. It has been observed that human males are able to detect how close a female is to ovulating through olfactory cues, in this case, body odour. An experiment was conducted to show this where men smelled the scent of women, once when they were at a low-fertile point in their cycle and again when at a high-fertile point in their cycle. A low point in the fertility cycle is where a female is not able to get pregnant as there is not an egg available while a high point is where it is likely to pregnant as there is an egg available. It was determined that females were in a high point of their fertility cycle by hormone testing that confirmed the women ovulated within two days of the sample being collected. Results showed that males could distinguish between the low and high fertile scents and found the scent where the female was the most fertile to be more attractive (Gildersleeve et al, 2012). Females are also able to detect the fertility status of other women and can impact how they interact with one another. An experiment was conducted where women were given scents of females at different stages in their fertility cycle and were told to rate them. It was observed that females found the females that were not on any hormonal contraceptive and at their most fertile point in their cycle to be the most attractive. They also observed that females who were on a hormonal contraceptive were rated as attractive as the females who were the most fertile during their natural cycle (Fales, Gildersleeve & Haselton, 2017).

Body odour is also used to determine the genetic compatibility of a potential mate. Body odour can especially indicate the genetic similarity or difference of aspects of the immune system where it can be more beneficial to have someone who is similar or different depending on the factor. For the Human Leukocyte Antigen (HLA) it is more beneficial for a couple to have very different HLAs as this can result in a child that is heterozygous and has a more adaptable immune system. Because of this, human females find males that have a dissimilar HLA to have a more attractive body odour than those that have a similar HLA to them, however, this phenomenon seems to be affected by contraception (Croy et al, 2018). An experiment was conducted where couples were genotyped and then were exposed to HLA similar and dissimilar scents and then rated how attractive they found the odour. It was observed that men didn’t show any notable preference and the same was also seen in females that were on a hormonal contraceptive. However, women that were not on a hormonal contraceptive displayed a higher attraction towards men that had a different HLA to them and was not affected by the odour being from their partner or a stranger (Croy et al, 2018).

Body odour can also indicate to a potential mate the resources available and good health by indicating a healthy diet. A diet that consists of high amounts of fruits and vegetables is correlated with good health and people who follow this diet have more attractive body odours. This is observed in an experiment where males provided sweat samples and information about their diet. Females then smelled the different samples and the males that had a diet with the highest amounts of fruit and vegetables were rated to have the most attractive scent (Mahmut et al, 2017).
Body odour is an important reproductive strategy related to mate choice for procreation which is confirmed by the reduction in attraction to body odour seen in homosexual males. This is observed in an experiment where heterosexual males and females and homosexual males rated the importance of different factors. It was observed that heterosexual females and males valued body odour to be important in choosing a potential partner more than homosexual males who found the sound of a partner’s voice to be more important (Cunningham & White, 2017). Because those who value indicators of reproductive fitness, the heterosexual males and females, it makes sense that body odour would be more important as it indicates how fit they are to produce offspring. Reproductive fitness is the fitness ability fo an individual to reproduce successfully. While these results seem promising, the above experiment was conducted by participants self-rating how important each factor was which could introduce some measurement error as people are not always honest. Because of this these results need to be thought of critically and potentially further research to understand this further.

Conclusion:

There are a number of factors which influence how sexually attractive a person is determined to be by potential mates with one of these being body odour. Both males and females are able to use body odour to detect if a female is fertile and find females that are close to ovulation to have the most attractive body odour. Females are able to use body odour to determine how similar they are genetically to potential mates, in particular, females find males that have a different HLA to have the most attractive body odour as it will have the best probability to result in children with more adaptive immune systems. Also, body odour can indicate the diet of a mate, indicating the resources they have access to, by having more attractive body odour when they have a healthier diet. Because of these reasons, body odour is an important reproductive strategy that is further demonstrated by the reduction in body odour attraction seen in homosexual males.

Literature Cited:

Croy, I., Hummel, T., Kromer, J., Pietrowski, D., Sauter, J., Schafer, L., Schmidt, A & Sorokowska, A. (2018). Human Leukocyte Antigen similarity decreases partners’ and strangers’ body odor attractiveness for women not using hormonal contraception. Hormones and Behaviour, 106, 144-149.

Cunningham, C & White, T. (2017). Sexual preference and the self-reported role of olfaction in mate selection. Chemosensory Perception, 10(1-2), 31-41.

Gildersleeve, K., Haselton, M., Larson, C & Pillsworth, E. (2012). Body odor attractiveness as a cue of impending ovulation in women: Evidence from a study using hormone-confirmed ovulation. Hormones and Behaviour, 61(2), 157-166.

Fales, M., Gildersleeve, K & Haselton, M. (2017). Women’s evaluations of other women’s natural body odor depend on target’s fertility status. Evolution and Human Behaviour, 38(2), 155-163.

Mahmut, M., Stephen, I., Stevenson, R & Zuniga, A. (2017). Diet quality and the attractiveness of body odor. Evolution and Human Behaviour, 38(1), 136-143.

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