Y chromosome under attack

An ANU scientist, working with the University of Newcastle, has confirmed that the male Y chromosome is under attack and will eventually self-destruct.

Dr Jenny Graves, ANU Research School of Biological Sciences, and Dr John Aitken, University of Newcastle, have reported that the human Y chromosome (the genetic characteristic for males) is disappearing at the rate of five genes per million years.

"With less than 50 genes in total, the Y chromosome will be gone within 10 million years," Dr Graves said. Paul Waters, a PhD student in Dr Graves' group, has been looking at the history of genes on the Y chromosome and found that there were only a few left from the original Y, and only about 40 from a region added to the chromosome relatively recently.

Dr Graves said Dr Aitken's work supported these findings and offered an explanation for the cause. "Sperm generates reactive oxygen molecules that make the DNA vulnerable to attack. This means that deletions of the Y chromosome that cause infertility are very common," Professor Graves said.

She believes that in the future sex determining genes will evolve on other chromosomes, as has already happened in two rodent species. "If this happens differently in different human populations, we might see the evolution of new human species," Professor Graves said.