However, the expert say that men could follow the path of a type of rodent that manages to reproduce despite not having the vital genes that make up the Y chromosome. Graves told the medical students that a second species of human beings could even be born in the future.
Prof Graves said, "You need a Y chromosome to be male". She also said, "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. The Y chromosome is dying and the big question is what happens then."
The male Y chromosome has a gene called SRY (Sex-determining Region Y) which switches on the development of testes and pumps out male hormones that determines maleness. Graves said, "Humans can't become parthenogenetic, like some lizards, because several vital genes must come from the male."
"But the good news is certain rodent species - the mole voles of Eastern Europe and the country rats of Japan - have no Y chromosome and no SRY gene," she added.