Why do women bother to have sons? Imagine a mutant female, one who, like many other organisms, can do without males and still have young. Her offspring will all be females who, like their mother, can reproduce without the help of males. The result: twice as many descendants and a growing pool of asexual women. But that is not what we see. So what are the evolutionary advantages of sexual reproduction? Acclaimed science writers John Gribbin and Jeremy Cherfas explain why we reproduce in the way that we do. Looking at everything from single-cell organisms to computer-dating agencies, they reveal how human sexual behaviour- like our attitudes to incest, promiscuity and homosexuality-is deeply rooted in our evolutionary past. Modern technology could soon make men redundant- if it wasn't for one tiny snag. It looks as if we're stuck with sex - and for the most surprising reason. This dazzling book explores its many astonishing oddities.