Male Sex Gene Still Quite Robust

Men can breathe again. They may not be doomed after all. US scientists said last night that the Y chromosome - the rope of DNA that distinguishes male from female - may not be withering away.

Two studies of the Y chromosome in Nature today confirm that the Y contains more genes than scientists had thought, and a set of safeguards that could protect genes that control sperm production.

Females have two X chromosomes, males have the X and the smaller Y chromosome. When sex chromosomes evolved, the Y may have carried more than 1,000 genes. Most of these have rotted away. The latest count is 78. Scientists had predicted that the Y chromosome could disappear within 5m years.

"Genes constantly are being bombarded with little injuries - mutations. Mutations can be beneficial or detrimental but more often detrimental," said David Page of the Whitehead Institute in Cambridge, Massachusetts. But comparison of the human chromosome with the chimpanzee identified a repair technique.

"The study shows the Y chromosome has become very efficient at preserving its important genes," said Richard Wilson of the Washington University school of medicine in St Louis, Missouri.