Scientists challenge male `Y` chromosome extinction theory

London: Theories that the male Y chromosome could become extinct within five million years may have been greatly exaggerated, scientists have claimed.

Previous research has suggested the male Y chromosome -- the biological keeper of all things male -- is shrinking and could disappear altogether within the next five million years.

But, studying on rhesus macaque monkeys, researchers at the Whitehead Institute for Biomedical Research at MIT found that while male DNA was lost at first, the rate of reduction tailed off, a newspaper reported.

The findings, published in the journal Nature, would put an end to the theories that men are facing extinction because the Y chromosome was dying out is well wide of the mark, the researchers said.

The theory, known as the "rotting Y theory", had claimed that three hundred million years ago the Y chromosome had about 1,400 genes, but now it has only 45.

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, the researchers found.

"For the past 10 years the one dominant storyline in public discourse about the Y is it`s disappearing," Prof David Page, a biologist who led the study, said.

Prof Page said: "Putting aside the question of whether this ever had a sound scientific basis the story went viral fast and has stayed viral.

"I cannot 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."

"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."

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