Getting pissed on by chimpanzees is a strong opener for Professor Carole Hooven’s new book Testosterone: The Story of the Hormone that Dominates and Divides Us, - a fittingly visceral image for the subject matter.
Hooven was collecting urine as part of her research on chimpanzees in Uganda. The primate golden showers raining down each morning from the Kibale Forest were being tested for testosterone, which provided researchers with the perfect measure for aggression in the chimp group.
Testosterone - or as Hooven calls it ‘T’ - is the key to explaining certain behavioural differences between the sexes, not just in chimps, but humans too.
There is a certain nervous energy in Testosterone. With Hooven seeming primed for a backlash. She spends most of the opening few chapters of the book articulating what she is not saying, rather than what she is.
This isn’t paranoia. Just last week Hooven received a walloping for an appearance on Fox News where she defended the use of the terms “males” and “females” in research settings. Acknowledging sexual dimorphism in the age of the internet is something of a minefield.
Hooven’s main thesis is pretty straightforward: sex difference, and in particular sex differences in hormone levels, have an important role in shaping human behaviour.
But Testosterone is very cautious about what behaviour it is talking about.
Hooven is keen to emphasise that males and females are vastly more similar than different in nearly all behavioural and cognitive respects. However, she notes there are on average differences in aggression and sexual drive that don’t appear to be the result of socialisation.
These differences appear cross-culturally and do not appear to shift significantly in social environments, or over historical periods. The cause for this sex difference? Testosterone both pre-natally and during puberty.
It’s important to re-emphasise that Hooven is not arguing for some simplified “men are from Mars, women are from Venus” thinking.
Indeed, she praises researchers such as Dr Cordelia Fine for pointing out many of the ludicrous claims about testosterone, including claims that men are intrinsically primed for leadership or career success because of a little extra androgen.
But Hooven is equally sceptical of claims that try to brush away statistics as pure gender socialisation. Men commit the bulk of violent crimes, are more likely to desire multiple sex partners and are more likely to respond aggressively during conflict. This surely can’t be purely due to cultural influence?
Instead, Hooven looks to our evolutionary history:
We have compelling evidence that human sexual dimorphism is largely the result of sexual selection: an evolutionary process that favors traits the improve the ability to acquire mates, either in quantity or quality. Men’s and women’s reproductive interests are similar but not identical…. For men, high social status is more reproductively advantageous than it is for women. Direct forms of competition, including physical aggression, help men to reach higher on the totem pole. Men also have a greater sex drive and preference for sexual novelty.
Now if this all sounds rather stereotypical, a slight watering down of the language may ease some concerns. On my interpretation, Hooven is speaking primarily about drives here, not complex human behaviours. As I’ve noted before, something like interpersonal violence is a highly complex behaviour - not reducible to the experience of ‘aggression’ per se.
When it comes to men and violence, you can think of aggression as the “match” but socialisation as the “fuel” which directs the behaviour. The vast majority of modern men are not violent, because civilised societies are quite good at socialising men to back away from and resist conflict. As Hooven writes:
Among healthy humans, with rare exceptions, there is not one gene or even on hormone that unilaterally causes anyone to act in any particular way or that sets anyone up for a specific kind of future.
The same of course is true for the sex drive - homosexuality, masturbation and shoe fetishes don’t have an evolutionary advantage, but they are different ways to sublimate the underlying sex drive.
So why is Hooven so confident testosterone is the reason for this difference?
Well there are a number of “human experiments” which show the influence of testosterone on real-life behaviour.
Hooven draws on everything from the eunuchs of Ancient China to the castrati of 16th century Italy to transgender people today as perfect case studies on the role of testosterone. For transmen, testosterone increasing sex drive and aggression is a frequent joke . But high sexual interest and aggression were the very things lost or never formed by eunuchs and castrati.
Then there are conditions such as androgen insensitive syndrome (where XY males, do not respond to testosterone) and congenital adrenal hyperplasia (where XX females express higher than normal levels of testosterone). Observations from both conditions point to testosterone as a masculinisation force.
Ultimately, Hooven makes a solid case for acknowledging the role of testosterone in shaping sex differences in behaviour. However, she is fairly light on the consequences of this finding and how society should respond. For example in one off-hand remark about her son she notes:
Characteristically masculine feelings are not toxic; he is not toxic for having them. What matters are actions, and he has control over those. We’ll try to guide him in learning to make the best, most respectful and compassionate choices.
This is a refreshingly out of fashion take on “toxic masculinity” but is rather vague on the appropriate level of socialisation required.
Yes, we shouldn’t make boys feel guilty for their hormones - but we should be teaching them to sublimate and channel those feelings into behaviours that aren’t harmful to others (particularly women).
How do we do that? This is something Hooven leaves completely unanswered, and ultimately her book falls a little flat as a result.
Males and females are different, sure. But how should we respond to those differences in ways that allow free expression of our drives, whilst deterring our more destructive masculine impulses?
The book fails to answer the most important question.