On her days off from the SFZS, she wrote freelance articles for San Francisco Chronicle's Sunday magazine, Image. Her writing career began in the public affairs office of the San Francisco Zoological Society, producing press releases on topics such as wart surgery on elephants. Roach bravely tries one out, while pursuing the cheery notion that masturbation might be good for your health.After college, Roach moved to San Francisco, California, and spent a few years working as a freelance copy editor. If 'clitoral erectile insufficiency' really exists, a female equivalent of the penis pump might help, by increasing blood flow to the clitoris. She tackles treatments for impotence – everything from pumps and penile prostheses to Kegeling – as well as research into what might be the female equivalent of male erectile dysfunction. At one point, in the interests of science and reportage, she and her husband Ed try to have sex while being scanned by a researcher wielding an ultrasound wand. She visits Topco, a sex-toy manufacturer, where she's shown an array of plastic penises, vaginas and anuses, modelled on plaster casts of top porn stars. On this roller-coaster ride, Roach is soon off investigating whether orgasm boosts fertility, which entails a visit to a crack Danish pig unit where farmers sexually stimulate sows during artificial insemination to boost fertility rates. 'It wasn't until the past half century that lab-based science embraced the pursuit of better, more satisfying sex.' Yet even today, there's the unspoken assumption that 'people study sex because they are perverts,' says Roach.

All are premised on the conviction that human sexuality is as worthy of scientific study as 'sleep or digestion or exfoliation'. In her quest for the latest insights, Roach visits sex research labs in London, Cairo, and Taiwan as well as the US. While she's sympathetic to scientists' desire to demystify sex and to help people with sexual problems, her sense of the ridiculous supplies regular doses of comic relief. Keenly attuned to what she calls the 'cringe factor', she manages to describe the nitty-gritty of genitalia in action without making you wish she hadn't. Californian reporter Mary Roach puts her quick wit to good service in this entertaining romp through sex research, past and present.

Bonk roach