TESTOSTERONE . by Joe Herbert . (OUP £16.99) Testosterone doesn’t always get a good press. Everything that’s unpleasant about male behaviour has been ascribed to the effects of this much maligned hormone. Violence? It’s all testosterone’s fault. Sexual assault and rape? Just blame testosterone. Yet, as Joe Herbert makes clear in his engaging whistlestop tour of the science surrounding it, testosterone is at the heart of human life. ‘Without our father’s testosterone,’ as he writes, ‘none of us would exist.’ It has only one basic function — to enable a male to reproduce, and for that it’s essential. Although this is the case and it’s impossible to think of ‘maleness’ without testosterone, it’s also important for sexual behaviour in women. The blood of an adult woman before menopause actually contains about five times more testosterone than oestrogen, the supposedly ‘female’ hormone. However, it’s as a metaphor for masculinity that testosterone is best known. All that’s unpleasant about male behaviour is ascribed to testosterone, yet as Joe Herbert explains, testosterone is at the heart of human life . It begins its influence in the womb as it helps to shape the distinctive characteristics of the male body. This influence continues immediately after birth. That three-month-old baby boy, sweetly smiling at you from his pram, may well have testosterone levels that rival his father’s. We don’t know why but, starting two weeks after birth and lasting for four to six months, a little boy’s testes are producing testosterone in substantial amounts. The hormone’s power then recedes, but returns — and how! — in puberty. Post-puberty, testosterone drives the competition for females. In the animal world, stags lock antlers, elephants enter the aggressive state known as musth and male rhinos go horn-to-horn. Even male giraffes, aroused by the hormone’s influence, flail at one another with their long necks. Elaborate colourings emerge in some species, designed to emphasise masculinity and attract female attention. In guenon monkeys the scrotum turns bright blue. They don’t seem to mind. They adopt the habit of sitting with their legs apart to show the female guenons just how big and blue they are. We can only be thankful that testosterone’s effects on sexual display in humans are not so visually dramatic. Adult human males have varying levels of the hormone in different circumstances. Entirely unsurprisingly, having sex increases testosterone levels. So, too, does talking to an attractive woman and watching pornographic movies. Winning at sports sends the levels racing upwards. Just supporting a winning team can have the same effect. It works in politics as well. A study showed that, during the 2008 U.S. Presidential election, Barack Obama supporters were pumped full of testosterone. Levels fell in the supporters of his defeated rival, John McCain. Testosterone also helps in the City. Another study, on a London trading floor, showed that male traders made more money on days on which their morning testosterone levels were higher than usual. A challenge is obviously stimulating. Surgeons facing difficult procedures often find their testosterone levels shooting up. One would assume that the theatre of war would have the same effect as the operating theatre, if not more so. After all, testosterone is supposed to be the hormone behind violence and aggression. In fact, soldiers in the heat of battle can have testosterone levels not much above those of men who have been castrated. It’s the appalling stress that reduces it. Once they leave the front line, however, the soldiers revert to more normal levels. When levels are high, the effects of testosterone on male behaviour are so strong that the human brain has had to find a multitude of ways of regulating and channelling them. The creation of laws, religion and customs has, to some extent, been shaped by the need to do so. In that sense, as Joe Herbert writes, ‘testosterone lies at the heart of much of our history’. His own fascination with the ‘simple but wondrous chemical’ that is his subject is clear. His book does a fine job of conveying that fascination to the rest of us.
The male hormone testosterone doesn’t always get a good press.
All that’s unpleasant about male behaviour is ascribed to the hormone.
Yet, as Joe Herbert explains, testosterone is at the heart of human life.