February 23, 2012
New Study Offers Evidence Against ‘Rotting Y’ Chromosome Theory
Males of the world, fear not -- researchers have determined that the chromosome which determines maleness is not shrinking after all, and concerns that the gender could be headed for extinction are apparently unfounded.
The study, which was led by Jennifer Hughes and David Page of the Whitehead Institute for Biomedical Research and the MIT Department of Biology, have compared the genes of the human Y chromosome to those of chimpanzees and rhesus macaques, according to Guardian Science Correspondent Ian Sample.
Their work on the chimpanzee Y chromosome was published in 2010, while their most recent study focused on the rhesus macaque, which Sample said split from the human lineage some 25 million years ago.
In the course of their research, Hughes, Page, and their colleagues discovered that in that time span, just one gene had been lost from the human Y chromosome.
Furthermore, they observed that the rapid deterioration of the chromosome appears to have slowed down considerably at least tens of millions of years ago, the Guardian reported.
According to AFP, "The men-are-doomed scenario" -- also known as the "Rotting Y" theory -- "leapt to prominence nearly a decade ago when scientists found that the male chromosome had dramatically shriveled. It had plummeted from a super-Y of more than 1,400 genes, several hundred million years ago, to a nubby little stump with just several dozen."
"That discovery triggered opinion that the Y was on the skids," the French news agency added. "In the worst scenario, men would disappear without some artificial means to keep the beleaguered male gender going. Some doomsayers said this would happen in around five million years -- others, in just 125,000 years -- as the Y chromosome went the way of the dodo."
Those predictions, BBC News Science and Health Reporter Neil Bowdler said, were inspired by comparisons between the two different human sex chromosomes, X and Y.
While the two were believed to be identical at one point, Bowdler said that the male chromosome now only has approximately 78 genes, compared to roughly 800 in the female chromosome. However, Hughes told the BBC that the Y chromosome had not lost a gene over the last six million years.
"For the past 10 years, the one dominant storyline in public discourse about the Y is that it is disappearing," Page said in a statement. "Putting aside the question of whether this ever had a sound scientific basis, the story went viral -- fast -- and has stayed viral. I can't give a talk without being asked about the disappearing Y. This idea has been so pervasive that it has kept us from moving on to address the really important questions about the Y."
"The Y is not going anywhere and gene loss has probably come to a halt. We can't rule out the possibility it could happen another time, but the genes which are left on the Y are here to stay," Hughes told Bowdler.
"I think it should finally put an end to the speculation about the demise of the Y." she added in comments made to Ewen Callaway of Nature, the journal which published the research on Wednesday.
In addition to Hughes, Page, and their colleagues from the Whitehead Institute for Biomedical Research, experts from the Washington University School of Medicine Genome Institute and the Baylor College of Medicine Human Genome Sequencing Center were involved in the study.
On the Net:
- Whitehead Institute for Biomedical Research
- Washington University School of Medicine Genome Institute
- Baylor College of Medicine Human Genome Sequencing Center