*** RECOMMENDED AS ONE OF THE TIMES' BEST SCIENCE BOOKS OF 2021 'With all the talk about testosterone in sex, sports and politics, we need a good explanation of the science and its implications, and this one is outstanding.' STEVEN PINKER, bestselling author of The Blank Slate 'There are whole books written about the idea that behavioural sex differences are a societal construct and how a male hormone we know influences animal behaviour somehow doesn't influence us. Hooven's book is a riposte to that silliness - and also a defence of a hormone that isn't just about aggression.' TOM WHIPPLE, THE TIMES, BEST SCIENCE BOOKS OF 2021 'Fascinating, vital, unputdownable.' JULIE BINDEL 'The definitive book on testosterone . . . A brave and significant book . . . simply fascinating and filled with extraordinary facts.' EVENING STANDARD 'Testosterone does what all superb popular science must do: it entertains as it educates.' THE WALL STREET JOURNAL Through riveting personal stories and the latest research, Harvard evolutionary biologist Carole Hooven shows how testosterone drives the behaviour of the sexes apart and how understanding the science behind this hormone is empowering for all. The biological source of masculinity has inspired fascination, investigation and controversy since antiquity. From the eunuchs in the royal courts of ancient China to the booming market for 'elixirs' of youth in nineteenth-century Europe, humans have been obsessed with identifying and manipulating what we now know as testosterone. And the trend shows no signs of slowing down. Thanks to this history and the methods of modern science, today we have a rich body of research about testosterone's effects in both men and women. The science is clear: testosterone is a major, invisible player in our relationships, sex lives, athletic abilities, childhood play, gender transitions, parenting roles, violent crime, and so much more. But there is still a lot of pushback to the idea that it does, in fact, contribute to sex differences and significantly influence behaviour. Hooven argues that acknowledging testosterone as a potent force in society doesn't reinforce stifling gender norms or patriarchal values. Testosterone and evolution work together to produce a huge variety of human behaviour, and that includes a multitude of ways to be masculine and feminine. Understanding the science sheds light on how we work and relate to one another, how we express anger and love, and how we fight bias and problematic behaviour to build a fairer society.