The original Y chromosome in mammals and marsupials evolved in a marsupial ancestor roughly 180 million years ago. And, up until about 25 million years ago, the Y chromosome was shedding genes, possibility to improve the chances of survival of male marsupials and mammals, according to genetic analyses.
The Y chromosome may therefore play a larger role in Turner syndrome and in health and disease differences between males and females than previously thought, a team of scientists argue. The analyses appear April 24 in two papers in Nature.