During evolution, men have lost most genes originally present on the Y chromosome, but that doesn't mean they're heading for the endangered species list, a genetic study suggests.
It has been suggested that the several hundred genes lost from the Y chromosome over 300 million years has degraded it to the point that men will someday become extinct, but one researchers says possessing the Y chromosome is not a death sentence as some believe.
David Page, head of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, says his study published in the journal Nature confirms the male sex chromosome has done an excellent job of conserving those collections of genes that have been a vital factor in seeing that men survive.
"This paper tells us that not only is the Y chromosome here to stay, but that we need to take it seriously," Page says. "This is an elite bunch of genes."
While he acknowledges men have lost many genes -- human Y chromosomes retain just 19 of some 600 genes once possessed in common with the X sex chromosome -- certain genes critical to important functions of cells throughout a male body have been saved.
"There are approximately a dozen genes conserved on the Y that are expressed in cells and tissue types throughout the body," he continued. "These are genes involved in decoding and interpreting the entirety of the genome."
The surviving genes find expression throughout the body in many more tissues than those genes that have not survived.
"All the survivor genes across different species had some common traits that differentiate them from genes that didn't survive. They are special, not lucky," Whitehead research scientist Daniel Bellott says. "We think that these genes are very important for male development, and are essential for male viability."
Just a single gene present on Y chromosomes is responsible for determining gender by triggering formation of testis and the production of sex hormones and sperm, but this represents just a fraction of what is controlled by the Y chromosome, Bellot says.
"Sex determination is really the role of one gene," Bellott says, explaining the remaining Y chromosome genes likely create subtle but important differences found between genders in many other tissues in the body.
"These genes may be doing a lot of things that are underappreciated," he says. "They may play a large role in differences between males and females outside the reproductive tract."
