London:
Men are on the road to extinction as their genes shrink and slowly fade away, a world-renowned British scientist has said.
Professor Jennifer Graves, a leading human sex chromosomes researcher with the Australian National University, Canberra, said the male Y chromosome needed to be a male was on the path to extinction and could run out within the next five million years.
Speaking at a lecture entitled 'The Decline and Fall of the Y Chromosome and the Future of Men', Prof Graves discussed the disappearance of the Y chromosome and the implications for humans.
"The Y chromosome is dying and the big question is what happens then," said Professor Graves, whose work on the past evolution of sex determination has paved the way for developments in diagnosis of gender disorders and gender-related disease in humans.
She, however, said men may follow the path of a type of rodent which still manages to reproduce despite not having the vital genes that make up the Y chromosome.
According to the top scientist, a second species of human beings could even be born in the future.
"Three hundred million years ago the Y chromosome had about 1,400 genes on it, and now it's only got 45 left, so at this rate we're going to run out of genes on the Y chromosome in about five million years," she told researchers at the Royal College of Surgeons (RCSI) in Ireland.
The male Y chromosome has a gene (SRY), which switches on the development of testis and pumps out male hormones that determine maleness.
She said it was not known what would happen once the Y chromosome disappeared.
"Humans can't become parthenogenetic [asexually reproduce], like some lizards, because several vital genes must come from the male," she was quoted as saying by the Daily Telegraph newspaper on Thursday.
"But the good news is that certain rodent species - the mole voles of Eastern Europe and the country rats of Japan - have no Y chromosome and no SRY gene.
"Yet there are still plenty of healthy male mole voles and country rats running around.
Some other gene must have taken over the job and we'd like to know what that gene is," she stressed.