Reprieve for men: Y chromosome is not vanishing

The Y chromosome is definitely the runt of our chromosome litter. Among our 23 pairs of these precious genetic bundles, pairs one through 22 are basically equal in size. But the Y — which holds genes that determine whether a mammal will be a male — is paired with the much larger X chromosome, and pales in size by comparison. Indeed the Y has only 19 of the approximately 600 genes it once shared with the X, 200 to 300 million years ago. But the decline and fall of the Y has stopped, according to new research published in this week’s Nature. Read more.