The truth behind testosterone

Testosterone is associated with lust and aggression, but does it deserve its reputation, and what would a world without it be like?
03 August 2015

Interview with 

Professor Joe Herbert, University of Cambridge


Testosterone is certainly a well-known hormones. When you hear the word, you mayRick Valente think of aggression, lust and "lads". But this chemical is the ultimate multitasker, providing many different functions in the body and mind, and impacts across society. So how does testosterone help reproduction in the first place, and what is the link between this hormone and being good at stock trading? Joe Herbert, from Cambridge University, has written the book on testosterone and has worked on many studies into the hormone. He spoke to Kat Arney...

Joe - Without Testosterone, you wouldn't be here, Kat, I wouldn't be here, nobody would be here. The world would be a very quiet place without testosterone. It's a very simple hormone. It's a very ancient hormone. It's present in amphibians, and reptiles, and birds, and fish, and of course all mammals. It comes most with the testes, a little bit comes from another gland called the adrenal which might be quite important in women, which I guess we'll come back to later.

Kat - I certainly don't have testes, last time I checked.

Joe - Good. I'm pleased to hear it. But in a male, it's overwhelmingly from the testes and this starts very early in life. I mean, within a few weeks of conception, the testes wakes up and starts pushing out testosterone. And that has enormous consequences.

Kat - So, let's talk a bit more about testosterone later in life. We've covered development very briefly. So, I do have this view that testosterone is kind of aggressive, manly sort of hormone. Is it really doing that? What's the role of testosterone in what we might describe as aggressive male behaviours?

Joe - Yes, doing all that - it has to. Testosterone has only one function really in the adultand that is to make the male fertile and sexy. Simple objective but complicated strategy because it has to do many other things than simply make him sexy. Let's make him attractive from the start. Otherwise, females won't agree. It has to make him aggressive so he will compete. It has to make him like taking risks so he'll get into a fight. With the possibility he might lose the fight and be damaged. And of course has huge effects on the whole of society. If you look at things we do every day, you can detect testosterone in practically everything.

Kat - So, one of the examples that I think you've studied is the idea that testosterone might be driving risk-taking in people who work in the financial sector. Tell me a bit about this. Was testosterone to blame for the credit crisis?

Joe - No, is the answer to that. But let me tell you why. If you look at a financial trading floor which is a huge room full of young men sitting in front of a lot of computers. What they're doing is, they're taking high risk quickly on the basis of lots of information. Now that's classic young male behaviour. Think of a young male creeping through the forest, hunting antelope - same problem. Or attacking a rival tribe in order to gain access to food or women or territory, exactly the same.

Kat - You just got to decide.

Joe - Absolutely. So, males have to make instant decision with the knowledge that if they lose, the results are dire. That's exactly what happens in traders. Now, the problem here is control. But all societies regulate testosterone. They don't allow males just to do as they please. If they did, it would be mayhem as you might imagine.

Kat - Have you been out in Norwich on a Friday night?

Joe - Yes, that's a good example of temporary loss of control because most of the time is controlled. Every religion, every society, every nation, controls who mates with who because rape is illegal in nearly all societies and so on. Now, if you get to international trading, you have the same problem here. You need control. What happened in 2008 was, not that males were doing anything different from what they normally had to do because in order to be a good trader, you've got to be a risk-taker, you got to be aggressive. What happened was a loss of control. They simply were doing it in uncontrolled way which is disaster in any context of testosterone.

Kat - Tell me about how you've been studying some of these risks and testosterone and that kind of behaviour in traders?

Joe - The first study we did was on real traders and we measured their testosterone and also another hormone called cortisol which is the stress hormone on several days and we related this to how much money they made. To our surprise, we got quite a marked positive relationship between levels of testosterone and their success. That is within the individual trader. Testosterone varies from day to day in men, but on days when their testosterone levels were particularly high, they made more money. Interestingly, their cortisol levels were very different and they responded to the uncertainty of the market. You can measure market of uncertainty. That was how volatile it is. If it's very volatile, up goes their cortisol and that's important too because that has effects on risk as well. But we went on to do this by looking at real trading. Not in real traders, but in graduate students. We made them play a game which looked very much like a trading floor. They had to basically bet on how their stocks did and they got real money. Not very much real money but they got some real money.

Kat - For students enough to make it worth it.

Joe - What we found there was, interestingly enough, that both cortisol and testosterone and we gave them both, different subjects on different days. But both increase risk taking, interestingly for different reasons. Cortisol made them like risk more. But testosterone didn't do that. What it did was made them optimistic. They thought they were better than they really were.

Kat - They felt kind of good and like, "Yeah, I could do this."

Joe - Doesn't that ring a certain bell?

Kat - So, that's really proving that testosterone is making people feel kind of good about themselves. It's making them want to put themselves out there and go for it which comes back to the sex thing?

Joe - It does. It comes back to initiative and drive and motivation, so you've got to believe in yourself. You got to believe that you can do it. As you know, one of the catches of young men is sometimes that's overdone. They believe they're better than they really are.

Kat - So, in terms of being able to manipulate testosterone, say, someone who doesn't feel that they're very outgoing, is there something that people could do maybe in terms of exercise or diet that might boost their testosterone. Is there any truth in this?

Joe - The best way to manipulating your testosterone is win something. The best way to reduce is to lose something. If you win a tennis match or a chess match or I don't knowget a promotion, or someone tells you how great you are, up goes your testosterone.

Kat - We've talked about testosterone with regards to men and what might be considered to be masculine behaviours, aggressive behaviours. I'm a lady, but am I still making testosterone and what's it doing for me?

Joe - You are making testosterone, Kat. You're making it for your ovaries and for your adrenals. Now, in males, the adrenal contribution doesn't matter very much because the testes make so much, it gets lost. But in you, roughly, around about half your testosterone comes from your adrenals, the other half is the ovaries, and your levels are about somewhere between a 5th and a 10th of that of an average male.

Kat - Is it doing the same kind of thing to me, kind of making me when I get out there and feel kind of sexy?

Joe - Sexy, certainly. It's highly important for libido. Whether it has other effects like it does on males is much less certain. But the suspicion is that it doesn't necessarily have the same effect because don't forget, you have a female brain whereas a male brain is substantially different, that's the reason why testosterone in a male will do different things than a female. Apart from sexuality, that's the common feature of both sexes.

Kat - Can you imagine what a world might be like maybe with no testosterone or if everyone had the same kind of levels as women? Would it just be calmer and generally more nice?

Joe - No not at all. Testosterone has got a bad press, but actually, it's responsible for a huge amount of get-up and go, of innovation, of drive, of motivation, of excitement. It's really a very interesting and valuable hormone. I'd hate the world to have no testosterone.

Kat - More testosterone all around. Thank you very much. That was Joe Herbert.


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