Finally geneticists have sequenced the entire X chromosome - well, 99.3 per cent of it - and their discovery, published in last week's issue of the science magazine Nature, does not auger well for the human male.
They found a large number of genes on the X chromosome - the female one - are essential to key brain functions. Alas, the Y, or male, one contributes - you guessed - mostly to what takes place below the waist. (To refresh your memory, two Xs make a girl and an X and a Y make a boy.)
Laura Carrel and Huntington Willard of Pennsylvania State and Duke universities analysed the genetic sequence and made an even more startling discovery. It was known that most genes on one of the two Xs in females had to be silenced so males and females would have roughly the same dose of gene products. Early in female development, cells randomly select the maternal or paternal X to be the active X. But Carrel and Willard found a whopping 15 per cent of the genes on the silenced X chromosome are irrepressible. They move around to escape being shut up, and so contribute to far greater genetic variability in women than men. It makes you wonder whether the far superior gene expressions of women may not be behind the cliche that men have trouble expressing themselves. Meanwhile, study after study has confirmed that the Y has been shedding genes for millions of years and is a fraction of its former glory. Lack of genetic variability, shrinking size... Guys, we are toast!