Jennifer Graves

The human Y chromosome has lost roughly 97% of the genes it inherited from its ancient ancestor over the past 300 million years.

And evolutionary biologist Jenny Graves has calculated that if that deterioration continues at the same rate, the Y could disappear entirely in a relatively quick five to 6 million years, which might seem like a while, but time flies, people.

Another evolutionary biologist, Jen Hughes of MIT's Whitehead Institute, argues that the Y lost genes rapidly early in its evolution, but then essentially stabilized with very few of its remaining core genes disappearing over the past 25 million years.

Those genes still perform important functions throughout the body.