What Made the Y Chromosome So Tiny?

The Y chromosome, a chunk of genetic code that is unique to male mammals, isn’t just physically smaller than the X. It also contains far fewer genes. The X has more than 1000 genes, while the Y has fewer than 200 —and most of them don’t even work. Why do men have this odd, stunted chromosome in their genomes? » 5/07/15 6:25pm 5/07/15 6:25pm