Research: Testosterone Does Not Cause Aggression

I recently shocked my daughter in a conversation when I told her I didn't believe in endorphins. Actually, I'm sure there are endorphins, I just don't think that's a good way to describe your state of mind: "I'm happy" is better than "I can feel the endorphins." Same for adrenalin, it's just as easy to say "I'm excited" as it is to say "I feel the adrenalin rush," ignoring other aspects of the sympathetic nervous system, the limbic system, and other physiological components that you can't feel directly, but they affect you. We have preconceptions about the effects of endorphins and adrenalin, and other natural parts of ourselves, but those preconceptions are socially constructed, we don't really know if it's adrenalin, or endorphins, or something else. We may, however, really know introspectively if we are excited, or tense, or happy. I guess I have a suspicion of laypersons offering mechanistic theories to explain their own behavior -- we're people, not robots.

An article in the current issue of Nature takes on our preconceptions about testosterone. You know what testosterone is; though women's bodies produce testosterone, men have forty times as much, it is the primary male sex hormone. Testosterone is used to explain why our prisons are full of men, why men get into fights, why men are sexually aggressive, why men are jerks. It's all part of our common folklore -- men act that way because nature made us that way. Testosterone makes us behave badly. Or so we believe.

Here is Nature News:

The popular idea that testosterone always makes people more aggressive has been debunked by researchers. A team based in Switzerland has shown that the hormone can make people behave more fairly in an effort to defend their social status.

Ernst Fehr, an experimental economist at the University of Zurich, and his colleagues used the 'ultimatum bargaining' game to test how testosterone would affect behaviour in a group of 121 women. Counter-intuitively, women who were given testosterone bargained more fairly.

But the idea that testosterone causes aggression in humans, as it clearly does in rodents, is so firmly ingrained in the human psyche that women who believed they had been given testosterone — whether or not they had — bargained much less fairly.

Women, not men, were tested because they have less variable 'baseline' blood testosterone levels.

The study is published in Nature. "It is a folk hypothesis that testosterone causes aggression," says Fehr. "But human society is more complex than this." Testosterone link to aggression may be all in the mind

We often discuss issues here that have to do with attitudes and beliefs about variations in aspects of gender. There are some people who believe that gender is a binary variable, you are either male or female, and once you have been assigned to a category you are expected to behave according to social expectations for that category. Some people believe this so strongly that they believe gender-related behavior norms should be enforced, for instance by punishing individuals who violate them. But, as the article says, "human society is more complex than this." I would put it this way: Human society is much more interesting than this. On a good day I might even say beautiful.

I'll skip the description of the study itself, which gave a shot of testosterone or placebo to some women and had them play a game where they could cooperate or compete. Subjects who had received the testosterone made more cooperative, fairer decisions.

Skipping down...

"In the socially complex human environment, pro-social behaviour, not aggression, secures status," says Michael Naef, an experimental economist at the Royal Holloway, University of London, who is a co-author on the paper.

That's a thought, isn't it? People respect a nice guy.

Skipping a little further ...

Adam Goodie, a psychologist at the University of Georgia in Athens who works on decision-making, says: "The paper is a major blow to the popular wisdom that testosterone simply makes you more aggressive and less cooperative — the true picture is not nearly as negative."

This re-opens the question, why are the prisons full of men? Men commit the vast majority of violent crimes, for instance. The civilized human being is a strange creature, optimizing two kinds of variables. As physical beings, products of evolution, we inherit physical bodies and the complicated layers of motives and drives that keep the species alive. And as social beings we are subtly and powerfully influenced by our culture and our language. There may be a physiological explanation for the aggressiveness of males -- there is certainly more to the physiology of sex differences than testosterone levels. Cross-cultural variations in violent behavior demonstrate that there are social factors at work, as well.

Sex and gender in human beings are complex abstractions. Men and women differ, on average, on many dimensions, but the distributions overlap -- though men are taller on average, some woman are taller than some men, for instance. Everyone who lives has a physical body, and everyone you know participates in a social system, a culture, a circle of acquaintances, a family, and those two domains of explanation cannot be separated. Science is able to help us understand ourselves and our neighbors, in this case it seems that one excuse explanation for bad behavior by men has been eliminated.