The idea that the male sex chromosome and its owners would someday vanish is based on the process by which our cells form sperm and eggs. These cells each contain pairs of chromosomes, or packets of DNA. When these cells divide, their chromosome pairs swap genetic information in a process called recombination (like shuffling two decks of cards before dividing them back into two decks).

Recombination allows the cells to repair genetic mistakes and mix and match genes. But unlike the other 45 chromosomes that carry human genetic information, the male sex chromosome, the Y, does not come with a matched partner to recombine with. Instead, it gets paired with an X chromosome. That means that when it comes time for cells to divide, the Y has no one to recombine with. …

But Hughes’ new research suggests that men can breathe easy. She and her colleagues sequenced the genome of the rhesus macaque, an Old World monkey whose lineage split from that of humans 25 million years ago. Prior to this study, researchers could only compare the human Y chromosome with that of the chimpanzee Y. Chimps split from humans 6 million years ago, giving a limited portrait of the evolution of the chromosome.