Most Men Take Testosterone For Granted But It’s One Of The World’s Most Powerful Chemicals

Attitudes about the role of men in today’s world are shifting, but what do our hormones have to say about that? RISING spoke to Professor Joe Herbert, author of Testosterone to find out…

RISING So, what does testosterone actually do, on a basic level? JOE HERBERT, NEUROSCIENTIST ‘Testosterone has a single simple function, which is reproduction and it does that in two ways: by acting on your testes to make good sperm, to make you fertile; and secondly on your brain to make you sexy. But the problem is, that isn’t enough, because in order to be functionally fertile you need more than simply to be sexy and to be fertile; you need to be competitive, you need to be attractive, you need to be aggressive and you need to take risks because reproduction, as we all know, is a risky business.’

RISING OK, but giving testosterone total control over our actions would bring a new meaning to the phrase ‘social hand grenade’ so how is it regulated? JH ‘It's still an amazingly powerful substance, it’s just that it's moderated and controlled by lots of other things. You can't let unbridled testosterone behaviour loose in society. No animal allows that. Humans have taken this fundamental, very powerful hormone – I mean without testosterone none of us would be here – and on top of that you have this secondary system of the great human brain, which regulates and controls testosterone-dependent behaviour. Not only do we have huge amounts of variety in the way we express reproductive activity, we also have huge amounts of variety in the way in which we regulate it, and there are laws and conventions, which other animals don't have.’

RISING What role does testosterone have in shaping society? JH ‘If you look at human history, wars and social selection and social competition, you can see that testosterone, which is fundamental to all these things, has a huge effect on the way in which human history has developed. I mean most of the maps drawn in the world are a result of war and all the evidence shows that the effects testosterone has on neural function is right at the basis of war.’

RISING What about right now – how is our modern lifestyle affecting our testosterone levels? JH ‘So, stress knocks your testosterone levels right down and that may possibly be one of the reasons why there has been a decrease in sperm count, as you may know, over the last 30 or 40 years because of the fact that more people now are exposed to an uncertain, stressful lifestyle. We don't know that but it's a plausible idea.’

If you win something, or if your football team wins a match, your testosterone levels will go up

RISING The internet is full of stuff about testosterone levels being connected with diet – is there evidence for this? JH ‘Not really, you know, there's a lot of guff talked about this – drinking pomegranate juice and stuff. There's no evidence. What you can say is two things: first of all testosterone levels are highly variable, they vary a lot and the idea that you just go on pumping out testosterone day after day is wrong. It's affected hugely by stress, or losing, or indeed by winning. If you win something, or if your football team wins a match, your testosterone levels will go up. That’s been shown for example, in male ice hockey players. So it's highly reactive to circumstance. If you look at soldiers who are on a front line and in constant danger their testosterone levels go way down, very often. Whereas when they get back into base the levels go back up again. And being a father reduces testosterone levels quite a lot in men!’

RISING So what happens to you when your testosterone levels plummet? JH ‘People who have very low levels of testosterone complain of several things: first of all low sex drive and a loss of ability to have sex. Secondly, of course, a loss of energy; testosterone is a great energy provider. When you talk to people who've been given testosterone for a variety of reasons, they say that their energy and their zest for life goes up, and their competitiveness goes up too. They become more, not aggressive, but more competitive and eager to get into contests with other people.’

On days when financial traders’ testosterone levels were high they made more money

RISING What about the effect of testosterone on risk taking and success? JH ‘We did a study a few years ago where we looked at financial traders, making bets on commodities and we found that on the days when their testosterone levels were high they made more money. Testosterone levels between individuals didn't tell you who was going to make more money – what it did tell you was on the days where, for whatever reason, their testosterone levels were high, they made more money than on the days when it was low.’

RISING Was that because they were taking more risks? JH ‘When we gave testosterone to graduate students [in a study] and they played a kind of game, which mimicked financial trading, we found that when they got testosterone, they preferred riskier bets. They did that, interestingly, not because they liked taking a risk, but because they became more optimistic – they thought they would do better than they otherwise would.’

RISING So, are the levels of testosterone in your body the whole story of how it acts on you? JH ‘Most of the time testosterone levels are way beyond what you actually need. Levels of testosterone aren't the only thing you need to think about because people’s sensitivity to their own testosterone varies quite a lot and we know why – it's a biochemical genetic variation in a particular molecule in the brain which makes your brain more or less sensitive to testosterone. So, you may get two blokes with the same levels but one will be more sensitive to testosterone than the other and you won't know that until you actually measure this particular gene.’

RISING Can your sensitivity to and levels of testosterone determine the kind of person you are? JH ‘Testosterone doesn't act by itself. Temperament isn't determined by adult testosterone; it's determined by a whole slew of genetic and environmental and experiential events, which determine the kind of person you are, and it may very well be that you could be a highly dominant male with low levels of testosterone. I have to say the probability is less than the opposite. I mean in most studies of animals certainly and in some human males, high-ranking males tend to have high levels of testosterone.’

RISING So could social status be decided by testosterone, or does having a higher status give you more of it, because you’re winning? JH ‘Whether that's the cause of their rank or the result is an interesting question – in monkeys, for example, when you take away the top male and see what happens, the second male’s testosterone level rises as he becomes the dominant male. So, which causes which, is another matter.’

Prescriptions for testosterone in men over 40 have tripled in the last 10 years

RISING What happens to the testosterone in our bodies as we get older? JH ‘In many men, as you get older testosterone level declines. It's very variable; some men it doesn't, some men it declines quite a lot, it just depends. There’s no doubt too that if it declines, say to about half your normal levels, this will have an effect.’

RISING Is it becoming more common for men to have hormone levels ‘topped up’? JH ‘The prescriptions for testosterone in the UK to males over 40 have doubled in the last ten years and in the United States they've actually tripled. So there's a huge demand for testosterone in older men and it's increasing all the time. Whether or not it has any beneficial effects is much less certain, nobody really knows that because nobody's looked very carefully – but it’s a legitimate way, if you can persuade your doctor to do it, of taking testosterone. Restoring your testosterone levels makes sense but to do that you need pretty careful and sophisticated [medical] supervision and that isn't always the case.’

RISING Yes, you only have to look at some of the guys coming out of gyms these days to see testosterone abuse… JH ‘The other way [people take testosterone] as you say, is athletes, and testosterone-taking or commonly compounds like testosterone is very common. We're seeing pictures of bodybuilders with bizarre muscular elements – that's due partly to training but much to do with overdosed testosterone. These people have serious health problems later in life and they do themselves great damage by taking these enormous amounts of testosterone, which is of course why it's banned, apart from the fact that it's unfair.’

RISING Is there anything we’re still to learn about testosterone? JH ‘The thing which strikes you, and it always strikes any neuroscientist, is how ignorant we are about exactly what testosterone does. When I said to you testosterone makes you sexy, and it does, how? What does it do to your brain?’

RISING What’s the most surprising thing for you about testosterone? JH ‘First of all how amazingly powerful this substance is and how it's shaped our destiny, our history and our individuality and our lifestyles in a way which we maybe don't want even to admit because it's a simple hormone. It's a very simple chemical. And we have taken this fundamental power and diverted it across geography and throughout history so that testosterone-regulated behaviour in the sixteenth century is quite a lot different from what it is now and testosterone hasn't changed nor has the effects on the brain changed. What has changed is the way in which we use that.’

WHAT NEXT? Read more about the molecule that has shaped your life in Joe Herbert’s book Testosterone now available in paperback.