We know that chromosomes are the microscopic rods that hold genes. Chromosomes generally come in matched pairs, with one member of each pair from Mom and the other from Dad. But men have one wildly mismatched pair, the X and the Y. The Y chromosome makes males. If you inherit it from your dad, you’ll become a boy. If you get an X chromosome from Dad instead, you’ll be a girl.
The idea that men had their own chromosome was recognized in the early 1920s, and the Y was one of the first to be identifiable under a microscope. But while researchers could figure out what kinds of genes the X chromosome carried by studying generations of families, this approach failed when applied to the Y. For decades after that, scientists regarded the Y as a like a wasteland, not of much significance except that it carried some gene that determined gender in a fertilized egg.
That view has largely held on, even though evidence has emerged that the chromosome carries at least two dozen genes or gene families. That’s a small number compared to maybe 2,000 or more genes on the X.
Scientists are now close to deciphering the makeup of the Y chromosome. , Scientists hope to have worked out the DNA sequence of the Y chromosome. The work should help researchers learn about causes of male infertility, because it’ll help them identify genes on the Y that men need to make sperm.