Nature Magazine and several other news outlets have been covering recent research that suggests that disappearance of the Y chromosome may not be in the cards. David Page and Daniel Bellott report in the April 24th issue, that genome sequencing across eight mammalian species demonstrates a great shrinkage due to loss of genes early on but that this loss peaks out about 125 million years ago and has remained relatively stable as of 25 million years ago when monkeys split off chimps. They write “That stability, he argues, comes from a vital core of about 12 genes on the Y that have nothing to do with male sex determination, sperm or male sex organ development. Instead, these genes ensconced on the Y are expressed in other tissues, such heart cells and blood cells. They are responsible for vital cellular functions, such as protein synthesis or regulating the transcription of other genes. That means the Y is important to the whole organism’s survival, he says, and so survival of these genes would be favored by evolution.” but Jennifer Graves and others debate this as would the existence of humans who have only one X chromosome and no Y chromosome… though they may have compromised fertility, it does not seem that the Y is essential… but perhaps provides a selective advantage.