The tired trope of aggressive male sexuality is a pervasive one. The story goes like this: because men are full of testosterone and sperm as well as unhindered by the consequence of pregnancy, their sexuality is naturally brutish and promiscuous. Testosterone fuels aggression, billions of sperm want hundreds of outlets and nature failed to offset these desires with physical dangers associated with reproduction.

The compliment to this heterocentric sex story is that women, with their limited eggs, lack of testosterone and pregnancy burden are naturally chaste and self protective. Any sexual adventurousness or licentiousness is only done to please men and keep them around so they will help with the child rearing.

A simple and neatly packaged explanation of human sexuality. But it’s wrong. Let’s do some debunking.

Myth No. 1: Testosterone makes men aggressive.

Origins: The idea that testosterone is an aggression correlate comes from an experiment that found castrating male mice reduced combativeness. Naturally, culture extrapolated these findings to humans and claimed testosterone had the same effect on male humans.

Reality: In a 2009 study, European researchers administered either .5 mg of testosterone or a placebo to male participants before engaging them in a game of cooperation that involved negotiating money distribution with other players. They could make an offer as fair or unfair as they wished and those on the receiving end could choose to accept or decline. The findings? Testosterone recipients made fairer offers, a direct contradiction with common beliefs about testosterone and aggression. Researchers suggested that testosterone influences a sensitivity towards status which is expressed as cooperativeness in pro-social situations.

[NOTE: The relationship between testosterone and sexual desire is a slightly different, albeit unclear, story. There is evidence to suggest that testosterone influences sexual desire in males and somewhat less in females. However, our desires are also regulated and influenced by a myriad of psychological and external factors. Stress, diet, and sexual beliefs likely have more of an effect on our sex drives than this hormone.]

Myth No. 2: Plentiful and easy sperm production encourages promiscuous behavior in men.

Origins: The biological definition of male and female has to do with size of gametes, where male gametes are always smaller than female gametes. Male gametes are often mobile and easily replenished,especially in the case of humans. The theory (called Batemen’s Principle) states that females are choosier when selecting mates because of their limited lifetime gamete supply. (The idea comes from Angus Bateman’s 1948 fruit fly research that studied phenotype distribution via genetic mutations among offspring.) To simplify his assertion: male reproductive success is positively correlated with number of female mates.

Reality: Modern researchers invalidated Bateman’s findings when they reanalyzed the original data. None of the findings were statistically significant and the study had many methodological flaws. In 2010, researchers in the UK put forth a contradictory reading on fruit fly sexual behavior that posited female promiscuity as essential to some species’ survival. The press release on EurekAlert says it best:

This study suggests that polyandry reduces the risk of populations becoming extinct because of all-female broods being born. This can sometimes occur as a result of a sex-ratio distortion (SR) chromosome, which results in all of the Y chromosome ‘male’ sperm being killed before fertilisation. The all-female offspring will carry the SR chromosome, which will be passed on to their sons in turn resulting in more all-female broods. Eventually there will be no males and the population will die out.

Of course, these are studies on insects. What about humans? Overall, social factors influence promiscuity and choosiness for both genders greater than any biological factors such as gamete production. Most people have multiple partners over a lifetime, though it is hard to discern true numbers as self-reporting of partners is often misleading. (For a more in-depth explanation, check out this Livescience article.) Basically, there is no evidence that human sexual partner selection patterns are directly influenced by biological gender.

Myth No. 3: Risk of pregnancy mitigates sexual desire and behavior.

Origin: Likely extrapolated from the Bateman Principle that states reproductive costs influence sexual mating patterns.

Reality: Once again, sexual behaviors are not influenced solely by biology, especially in highly social species. The idea that women are choosier about sex because of the physical ramifications of pregnancy ignores birth control, social aspects of fatherhood (such as negative views of “deadbeat dads” or legislation aimed at combating absent fathers), and non-reproductive sex acts. Considering that 49% of U.S. pregnancies in 2001 were unintended, I really question pregnancy avoidance as a motivating factor for sexual selectivity. What I think is more likely: social ramifications for females. In the face of a social narrative positing females as naturally sexually selective and males as naturally aggressive, any female with a higher number of sexual partners violates common wisdom and is perceived as deviant, whether or not this behavior really is deviant. (Remember, we don’t have any reliable data on number of sexual partners in populations because the data is always self-reported and there is a strong social bias for people to misrepresent their numbers.)

Why does this any of this matter? In social debates about sexuality, this narrative is repeatedly employed to inaccurately discuss porn, justify rape and reinforce restrictive gender stereotypes. Tune in tomorrow when I discuss sexual stories that contradict this narrative in “Brutish” Male Sexuality Part 2.

ETA: This post was also published at AlterNet where a commenter questioned the minimal amount of evidence I offered. My response below, explaining more of the studies on testosterone-behavior links.

Greetings, You’re very right to question my argument in light of the limited studies I offered in my blog post. (Because my audience is the general population and not always academically inclined, I try to break it down simply and cite sources that my readers can access.) I’m happy to go into greater detail about studies looking at testosterone-behavior connections in humans. The first thing I want to stress is that testosterone effects are not direct and that any behavioral expressions are modified and influenced by psychological factors such as character traits and environment or social situations. One very concrete environmental example of this is stress reducing levels of testosterone, on which several studies agree. (Kruez, Rose and Jennings, 1972; Thompson, Debbs and Frady, 1990; Rabe, Karson, Howard, Fubin and Poland, 1990) Daryl O’Connor has led several studies (2002, 2004, 2007) researching the relationship between behavior and testosterone and have found that above average levels of testosterone are not associated with aggressive behaviors and that behavioral expressions are modified by the circumstances as well as individual personality traits. With regards to sexual behaviors, the 2004 study found that above average levels did not increase levels of libido or frequency of sexual contact. One thing to note is that *below average levels* are related to low levels of libido and sexual function and testosterone can be used as a therapy. But this relationship only appears with low levels not high levels. So, if testosterone is not related to aggression, what is it related to? Alan Mazur (book: “Biosociology of Dominance and Deference”, 2005) and Allan Booth are two other researchers studying testosterone-behavior relationships (1998 study and a 2006 meta-analysis of research along with Douglas A. Granger and Katie T. Kivlighan) What they assert is that testosterone is linked to dominance behaviors. Now, dominance is not the same thing as aggression. Dominance exists within a social hierarchy and dominant behaviors with humans are determined by social values and mores. What this means in conjunction with the study I listed in my article is that testosterone is linked to seeking higher status in a social hierarchy, something that Mazur and Booth also assert. (There is also evidence that high levels of testosterone are linked with risk-taking behavior, which can be seen as a part of status.) Bringing this back to the popular myth of aggressive male sexuality: when considering the role of testosterone in male sexual behavior, the emphasis is on status and dominance does not mean aggression. I want to point out an interesting social phenomenon that I think illuminates the relationship. Since the 1970s in the U.S rates of reported forcible rape have dropped by a staggering 85%. One important thing to look at when trying to explain large social phenomenon like this is the social context in which it occurs. During this time period there have been large efforts and much criticism against male sexual domination of women and more legislation against forcible rape, such as states making spousal rape illegal. (The first being South Dakota in 1975 and the last being North Carolina in 1993). To me, what this indicates is that when a culture reconstructs what constitutes a dominant member, those seeking dominance alter their behavior. We should note, however, that broader social messages are not deterministic and experience as well as messages from peer and family will influence an individual’s understanding of defining dominant behaviors. My larger point is simply this: testosterone is one of hundreds of hormones involved in our highly complex endocrinology system, a system which has a very small influence on behavior. Even with the links to dominance, this in no way shows a gender-determined bias toward aggressive sexual behaviors. This is a social myth based on simplistic understandings of complex systems and environmental/situational interactions. Furthermore, our sexualities are highly complex in their expressions and our sexual behaviors are not determined by our biology. Thank you for pointing out the critical thinking red flag raised by my limited presentations of studies in my blog post. I hope the further evidence I presented lessens your reaction to my argument as rubbish. -The Sexademic