(PhysOrg.com) -- Men with strong immune systems are most attractive to members of the opposite sex according to a new study from the University of Abertay Dundee and partners.
The research, which identifies a link between testosterone, facial attractiveness, and the stress hormone cortisol is reported in this weeks Nature Communications journal.
The findings suggest that women might be more attracted to men with high levels of the sex hormone testosterone because they have a healthier immune system.
Sexual characteristics in male faces are testosterone-dependent, but how the sex hormone affects immune function is unclear. Dr Fhionna Moore from Abertays School of Social and Health Sciences, and collaborators, measured the immune responses of 74 Latvian men in their early twenties to a hepatitis vaccine, and determined the blood concentrations of testosterone and cortisol. They then asked Latvian women of a similar age to rank the participants by facial attractiveness on a 10 point scale.
The team found that men with a strong immune response had high levels of testosterone and were perceived as more attractive. Men with low levels of testosterone tended to have higher concentrations of cortisol, suggesting that their immune responses might have been inhibited by the stress hormone.
While previous research has discussed the relationship between testosterone and the immune system, this study is the first to directly link women's opinions of a man's attractiveness with the strength of his immune system. The authors suggest that this behaviour, previously observed in birds, could be explained through the fact that women seek for their offspring to inherit the healthiest immune systems.
Dr Moore and the rest of the team, who come from the University of Turku in Finland and the University of Daugavpils in Latvia, now hope to assess whether the results hold across cultures and across different age ranges.
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The paper Evidence for the stress-linked immunocompetence handicap hypothesis in humans was published in online journal Nature Communications.