Y Chromosome Not Going Anywhere, Study Suggests

The Y chromosome isn't going anywhere, researchers concluded after comparing the male chromosome in 16 African and European men.

"The Y chromosome has lost 90 percent of the genes it once shared with the X chromosome, and some scientists have speculated that the Y chromosome will disappear in less than 5 million years," said evolutionary biologist from the University of California, Berkeley Melissa A. Wilson Sayres said. "Our study demonstrates that the genes that have been maintained, and those that migrated from the X to the Y, are important, and the human Y is going to stick around for a long while."

Published in the journal PLOS Genetics, the report challenges the theory put forth by so-called "Y declinists" who argue that the chromosome is vanishing right before our eyes. The theory, described in a 2002 article published by Nature, is based on the observation that some mammals, including mole voles and spiny rats, lack a Y chromosome - their sex determining genes having relocated to other chromosomes.

Seven years later, Jenny Graves, a co-author of the 2002 study and researcher from Australian National University's Research School of Biology, again reiterated the warning, pointing to the disappearance of genes on the Y chromosome.

"Three hundred million years ago the Y chromosome had about 1,400 genes on it, and now it's only got 45 left, so at this rate we're going to run out of genes on the Y chromosome in about five million years," she said, according to The Telegraph, adding "You need a Y chromosome to be male."

The new study, however, reveals how the patterns of variation on the 16 men's chromosomes "are consistent with natural selection acting to maintain the gene content there." UC Berkeley wrote in a statement. That the chromosome boasts just 27 unique genes, rather than the thousands found on other chromosomes, just means it's gotten rid of extra baggage and can now travel light with only the essentials, the researchers argue.

"Melissa's results are quite stunning," said co-author Rasmus Nielsen, a professor of integrative biology who also teaches at UC Berkeley. "They show that because there is so much natural selection working on the Y chromosome, there has to be a lot more function on the chromosome than people previously thought."