Whitehead Institute geneticists have overturned the theory that the mammalian Y chromosome is essentially stagnant, instead they discovered that the Y chromosome is actually evolving rapidly and continuously remaking itself.
The findings offer the first evidence that a Y chromosome as evolutionarily old as the human Y is in fact still evolving, says Andrew Clark, a genetics professor at Cornell University who studies Y chromosome evolution in fruit flies.
"There's a dramatic amount of turnover, and it's not just degeneration — it's gain and loss of genes that do something on the Y chromosome," says Clark, adding that the new sequence comparison may also help researchers study male infertility, which is often driven by defects in the Y chromosome.
Hundreds of millions of years ago, the Y diverged from its sister X chromosome and became specialized for male-specific traits. Evolutionary biologists have theorized that it quickly lost most of its genes through a process known as degeneration, then lapsed into a fairly static state.