Relax! Male chromosome is not doomed, say scientists
FEARS that the male Y chromosome could be wiped out within five million years have been undermined by new research showing the drop in genes has stabilised.
A study of rhesus macaque monkeys found that while male DNA was lost at first, the rate of reduction tailed off.
Researchers said they hoped their findings would put an end to theories that the Y chromosome was dying out after claims that its 1,400 genes had fallen in number to just 45 in the last three hundred million years.
The belief was named the "rotting Y theory" and was based on an assumption that the Y chromosome would carry on losing genes until it disappeared.
The study looked at the evolution of genes in the rhesus monkey and found it kept just three per cent of its ancestral "autosome" or non-sex chromosome.
Older regions, or strata, of the chromosome have not lost any genes in the past 25 million years, according to the findings published online in Nature.
Biologist Professor David Page, of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, said: "For the past 10 years the one dominant storyline in public discourse about the Y is it is disappearing.
"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 it has kept us from moving on to address the really important questions about the Y."
Professor Page added: "The Y was in free fall early on and genes were lost at an incredibly rapid rate. But then it levelled off – and it's been doing just fine since."
The researchers said the evolution of the Y chromosome was characterised by a period of swift decay followed by strict conservation.
Lab researcher Jennifer Hughes, whose earlier work revealed a stable human Y for at least six million years, said: "We've been carefully developing this clear-cut way of demystifying the evolution of the Y chromosome.
"Now our empirical data fly in the face of the other theories out there. With no loss of genes on the rhesus Y and one gene lost on the human Y it's clear the Y isn't going anywhere."
Professor Page added: "This paper simply destroys the idea of the disappearing Y chromosome. I challenge anyone to argue when confronted with this data."