Women may prefer to pick socially dominant men for a fling.© Punchstock

Women are most likely to cheat on their long-term partner when they are at their most fertile, and they tend to choose genetically superior men for their fling. That's the claim of a study by Czech researchers, which found that the smell of a socially dominant male is most exciting to women in stable relationships, especially on days when they are ovulating.

Jan Havlícek, of Charles University in Prague, and his colleagues asked 48 men to complete a questionnaire, rating statements such as "I am the life of the party", in order to score the volunteers' social dominance. The researchers also asked them to wear cotton pads under their arms to collect sweat.

A group of 65 women then smelled the pads and rated the sexiness and masculinity of the scent. Women in the middle week of their menstrual cycle, the point at which fertility is at its peak, tended to prefer the smell of the men who scored highest on the dominance quiz. This preference was not shown by women at other points in their cycle.

What's more, the effect was only significant for women in long-term relationships, the researchers report in the journal Biology Letters¹. This shows that both menstrual phase and relationship status can have an effect on which men women tend to prefer, says Havlícek.

Mix it up

The results support a theory of mixed mating strategies, which argues that women should want different things from different men at different times. Females are expected to pair up with the males most likely to invest in parental care, but any affair is likely to be conducted with successful males who, although they may not be good dads, provide good genes.

"Other studies have shown that women are more likely to get involved in extra-pair affairs during their fertile period," Havlícek says. "We suppose that in such cases more socially dominant males would be preferred."

The idea is difficult to assess, because male quality is difficult to judge. Other researchers have used measures such as the 'ruggedness' of a man's face, or the symmetry of his features.

Havlícek and his team argue that a high dominance score is a reflection of high mating quality. "Such individuals are more likely to reach high social status," he says. "And this may reflect high genetic quality."

Perhaps the most controversial part of the study is the claim that women find the smell of sweaty cotton pads enticing. "Some raters found particular body odours sexy; others simply found them 'not repellent'," Havlícek admits. "But laboratory conditions are rather unnatural, and the smells would be judged more positively in more relevant, that is, intimate, conditions." 

Charles University, Prague

• References

  1. Havlicek J., Roberts S. C. & Flegr J. Biol. Lett., doi:10.1098/rsbl.2005.0332 (2005).