Q: Do high testosterone levels make guys “players”?
Testosterone (T) levels are associated with sexual behavior and function. T plays a role in both mating and parenting. Married men tend to have lower T levels than single guys. Men who are fathers tend to have lower T than those who are not. On an individual basis, T levels tend to drop when you partner/marry and drop when you become a father. On a national average basis, for reasons yet uncertain, men’s T levels have been declining with every recent generation.
T correlates to number of sex partners. The CDC says that the median lifetime number of opposite-sex partners among sexually experienced men aged 25-49 years of age is 6.3 (for women, it’s 4.3) and nearly 60 percent of men have had nine or fewer partners (for women, it’s over 75 percent with nine or fewer).1 Another study found the average number of sexual partners for men and women in the United States is 7.2.2 Research published in Hormones and Behavior found that “T is positively and sizably associated with the number of opposite sex partners in men” even when controlling for potential confounding variables.3
A recent survey of middle-aged men published in Biological Psychology found a “robust relation” between higher testosterone and increased unfaithful behavior.4 Among men with partners, a study published in the Journal of Sex Research found higher T is associated with concurrent or “overlapping” partners.5 But correlation doesn’t mean cause. Other factors and directives may influence both T levels and sexual behaviors – i.e., something else may affect both.
Humans, like all organisms, have been biologically programmed over millennia. Although we are free to make intentional choices to override this programming, these programs guide us far beneath our conscious awareness. Nature’s primary directive for all species is to pass on copies of their genes. The survival of the gene, not the individual, is paramount. Mating and raising the gene-bearing offspring can be seen as the core around which all animal behaviors revolve. For reproductive purposes, we can largely divide animals into two buckets. In “tournament species,” like chimpanzees, the males fight each other and the winners do all the mating. A small number of big, aggressive males leave behind a wake of pregnant females. In monogamous “pair-bonding species,” like marmosets, females seek out smaller less “binary” males who look and act more like them and are more likely to share parenting duties.6
In all species, sexual behaviors are tied to reproductive advantages. T plays a role in mediating what’s needed to pass on genes. The Challenge Hypothesis7 suggests that T levels fluctuate to meet environmental challenges. For example, in humans, the T levels needed for courtship tournaments and bedroom fireworks are different than those suited for being a good partner/husband and father.
Settling down and staying bonded with our first love would not help spread our genes.8 Almost all mammals, humans included, have a built-in mechanism that scientists call the “Coolidge Effect,” which makes us more sexually responsive toward new, unfamiliar mating partners when the fertilization job appears done. The evolutionary benefit is that a male can spread his genes among multiple females, which may be why research shows that human men are driven to seek “the strange” more than women in everything from a guy’s head-turn to check out an unfamiliar female on the street9 to looking at porn10 and engaging in one-night stands.11
Is the Coolidge Effect a sign that humans aren’t evolutionarily programmed to be monogamous? While traditional narratives note monogamy is a feature of human mating throughout societies,12 in “Sex at Dawn: The Prehistoric Origins of Modern Sexuality,” authors Christopher Ryan and Cacilda Jethá argue that monogamy is an unnatural state for our species, citing the history of human development and pointing out that today’s marriage rates are down while divorce rates, adultery and flagging libidos are up.13
Maybe the truth is more nuanced than that. As pointed out by evolutionary biologist and neuroendocrinologist Robert Sapolsky, humans are odd creatures combining the features of both tournament and pair-bonding species. Individual men may behave more like “tournament males” or like “pair-bonding males” in various contexts and individual women may be more attracted to one or the other at various stages of their lives. Which leads to the question: If humans are still evolving as a species, do generationally declining T levels and the societal shift away from traditional (binary) gender norms suggest that we are becoming more of a pair-bonding species? If so, where might that lead?