ÐÓ°ÉÔ­´´

The X in Sex: How the X chromosome controls our lives by David Bainbridge, Harvard University Press, $22.95/£15.50, ISBN 0674010280 Reviewed by Mark Ross

BEING crazy about a particular chromosome can provoke strong reactions in colleagues and friends – bewilderment, sarcasm, possibly even a hint of envy. So it’s always heartening to find others who are similarly crazy, and particularly when they choose the right chromosome. In The X in Sex: How the X chromosome controls our lives, David Bainbridge proclaims his passion for the X chromosome, producing an account that is accessible and entertaining.

In a skilful opening manoeuvre, Bainbridge builds an apparently unassailable case for the importance of the other sex chromosome, the Y. After all, the Y chromosome in mammals is the critical trigger to male development, and the absence of the Y chromosome appears to lead by default to female development. The X chromosome, despite being a sex chromosome, seems to have relatively little to do with this process of sex determination.

At this point, I wondered if the author might have backed the wrong horse. This is what readers are meant to think, of course. The rest of the book makes you realise that the Y chromosome goes for a high impact, putting all its sperm in one basket, while the X has hidden depths and intricacies. The truth is that the behaviours of X and Y are inextricably linked. Bainbridge explores this link in a compelling tale that takes in how the sex chromosomes became sex chromosomes, and the very different consequences of this for women and men. Along the way, we encounter the Duke of Kent’s testicles, calico cats and non-identical identical twin girls. His story weaves science, history and the history of science (with a little religion for good measure) in a straightforward, anecdotal fashion that will appeal to scientists and non-scientists alike. The science is clearly and simply explained, and is illustrated with fascinating examples.

Oversimplification occasionally leads to inaccuracies, and the language is a little puerile in a couple of places. A few analogies are contrived: the one about the smoking and non-smoking chromosomes in a European restaurant is baffling, to say the least. But overall this is a highly readable and informative account of the best of human chromosomes (X and Y)!