Y chromosome doing just fine, say researchers

Posted by Emma Woollacott

Were the Y chromosome to die out, it probably wouldn't mean the disappearance of men - the relevant genes would likely move elsewhere.

All the same, the widely accepted belief that the Y chromosome is gradually withering has caused quite a bit of angst. Over the last 300 million years, it's lost hundreds of genes, leading many to suggest that it's on its way out altogether.

Now, though, a team headed by Whitehead Institute Director David Page says it's demonstrated that the chromosome in fact has a long, healthy future ahead of it.

"For the past 10 years, the one dominant storyline in public discourse about the Y is that it is disappearing," says Page.

"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."

Page's team has now sequenced the Y chromosome of the rhesus macaque —an Old World monkey whose evolutionary path diverged from that of humans some 25 million years ago — and compared it with the sequences of the human and chimpanzee Y chromosomes.

And they've found what they describe as 'remarkable genetic stability' on both the rhesus and human Ys in the years since their evolutionary split.

"The Y was in free fall early on, and genes were lost at an incredibly rapid rate," says Page. "But then it leveled off, and it's been doing just fine since."

In fact, the new research reveals that the rhesus Ychromosome hasn't lost a single ancestral gene in the past 25 million years - and the human Y's lost just one, in a segment that comprises only three percent of the entire chromosome.

The team says this shows that the Y's evolution is chracterized by periods of swift decay, followed by strict conservation.

"This paper simply destroys the idea of the disappearing Y chromosome," says Page. "I challenge anyone to argue when confronted with this data."