For a long time, biologists have predicted that the Y chromosome — the DNA that makes men men — was gradually dying out, and that it would eventually lead to the extinction of the male. Fortunately, a team of researchers has proven that isn't the case.
It used to be, a long time ago, that the X and Y chromosomes were the same size and shape. Then, about 166 million years ago, a huge chunk of the Y chromosome was turned upside down and reinserted. Nobody quite knows why. Ever since, the Y chromosome has lost 781 of the 800 genes it originally shared with the X chromosome, all thanks to mutation. It's this which led to speculation that it would eventually disappear.
But according to research from the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, that's not the case. A team of researchers has compared the human Y chromosome to that of the rhesus macaque — a primate that diverged from humans around 25 million years ago. The monkey's Y chromosome contains just 20 genes, and 19 of them are identical to those of the human Y.
So, in 25 million years, only one gene has been lost from the human Y chromosome. The research appears in this week's issue of Nature. Speaking to New Scientist, Jennifer Hughes, one of the researchers, said:
"We finally have empirical data that the Y chromosome has held steady over the last 25 million years. Most of the Y chromosome's gene loss happened almost immediately after it stopped recombining with the X chromosome."
In theory, the remaining 19 genes serve vital biological functions, so there's little chance of them disappearing. That means that we can rest happy in the knowledge that the rest of Y chromosome is going nowhere fast. Good news, chaps. [Nature and New Scientist via Gawker]
Image: The National Institute of Standards and Technology