Instead of doubling up to protect its genetic cargo like other chromosomes, the lone Y safeguards its genes by having sex with itself, an international consortium has found. Proving perhaps that nature has a sense of humor, scientists have discovered that the Y chromosome - the one that makes a man a man - has a remarkable ability to make do-it-yourself repairs.
June 20, 2003 — The human male sex chromosome does have the ability to repair itself and may not be headed for extinction as had previously been thought, according to a surprising new study.
A 40-strong team of researchers led by David Page of the Whitehead Institute at the Massachusetts Institute of Technology, report their findings in this week's issue of the journal Nature.
As well as having a previously unknown and elaborate back-up system for self-repair, the Y chromosome also carries 78 genes.
"The Y chromosome is a hall of mirrors," said Page, whose team has for the first time identified the full genetic sequence of a Y chromosome, from an anonymous donor.
Both the male Y and female X chromosomes are thought to have originally been the same size, but after the Y took on the sex-determining role for maleness it apparently began to lose genes. At this time it also lost the ability to pair up exactly with ...
The death of the Y doesn't mean the death of men. Men need only look to the mole vole for comfort. Burrowing through the soil of western Asia are two species of these rodents (Ellobius tancrei and E. lutescens) that have lost all the genes from their Y chromosome--in fact, they no longer have a Y chromosome at all. In one of these species, both males and females have been left with just the unpaired X; in the other, both sexes have two X's. No one knows how mole voles ended up being the first mammals to cross over into the Y-free future. But along the way, they must have evolved new genes--on other chromosomes--that are responsible for making males. One of those genes took over the job of SRY, and the chromosome on which it resides is probably on its way to becoming the new Y.
If our species manages to survive for another 10 million years, our descendants will go on making men even after their Y chromosome vanishes. But the change may not be smooth. Graves speculates that several new systems for determining sex could emerge within the global human population. People conceived under one system mi...
Chromosome which is found in males. XY = male. XX = female. Sperm can be either an X or Y chromosome. During fertilization, if the Y chromosome sperm reaches the egg, then the baby is a boy. If the X chromosome sperm reaches the egg, then the baby is a girl.