What drives men to sexual conquest and solo activities among women?
It’s testosterone, of course.
As the primary male sex hormone, it plays a leading role in the sexual development of men. But people often overlook the role it plays in female sexuality. Yes, women have testosterone too, albeit a lot less of it – and it’s a very different attraction, new research shows.
“It was quite surprising that the association with masturbation was stronger in women than in men,” said study director Wendy Macdowall of the London School of Hygiene and Tropical Medicine in the UK. “And that we did not see any connection between women and aspects of sex as a partner.”
Except for one, that is. In women, testosterone levels were significantly higher in those who had ever had a same-sex relationship.
For the surprising new study, Macdowall’s team used mass spectrometry to analyze testosterone levels in saliva samples from nearly 4,000 adults ages 18 to 74. Participants also completed a questionnaire to find out connections between hormone levels and sexual behavior.
Men who had relatively high testosterone or T levels were more likely to have more than one sexual partner at the same time in the past five years, the study found. And straight guys are more likely to have had a recent encounter.
The landscape was different for women.
People with high testosterone levels are more likely to have had a same-sex relationship at some point. They also masturbated more often – and recently.
High T has also been linked to having more solo sex for boys. But the masturbation connection was significantly stronger in women, the study found.
Participants who had at least one sexual partner in the previous year were asked about problems with sexual function, such as lack of interest or difficulty getting or maintaining an erection. No link of any kind was found.
As for the association between high T and greater urges to masturbate in women than men, Macdowall suggested that ultimately this could be due to social rather than biological factors.
Women, she said, may be more vulnerable to social pressures and norms than men – and those pressures are likely to be less when alone than with someone else.
“It is said that masturbation can be a ‘true’ measure of sexual desire because it is a private sexual activity and less of a social influence,” Macdowall explained.
Still, two experts who reviewed the results said that the overall influence of hormones on the sexual habits of men and women appears to be relatively small.
“Ultimately, the bulk of the evidence does not support relationships between normal T levels and sex drive or partner numbers in either sex,” said Carole Hooven, professor of human evolutionary biology at Harvard University. “So this surprises me.”
David Puts, associate professor of anthropology at Pennsylvania State University, was less surprised at the idea that a high T could affect sexual behavior. But, he added, the effect seems modest.
“It is particularly interesting why, from an evolutionary point of view, we see relatively modest relationships in humans compared to, for example, deer or hamsters,” said Puts.
For example, he found that humans – and our ape cousins - unlike many other animals, do not have a specific breeding season that is triggered by hormonal surges.
From an evolutionary point of view, Puts added, this could be because our ancestors “likely lived in an environment where temperatures and food availability were stable all year round, so it made little sense to limit breeding to specific times.” .
According to Puts, the real question could therefore be: Why do sex hormones such as testosterone still have an influence on human sexual behavior at all? Are some of these hormone-behavioral links just evolutionary holdovers?
However, in the absence of an immediate response, Puts said these effects exist but are not large.
“And that variation in sexual interest and activity in each gender may be better explained by other variables like social factors,” he added.
The results were published online this week in the Journal of Sex Research.
Harvard Medical School has more on the role of testosterone.