Will Men Become Extinct?

Will men become extinct? It's entirely possible, according to recent scientific research performed on the single genetic element that makes a man a man: the Y chromosome. This conglomerate of nucleotides and proteins, whose sequence codes for only 23 distinct proteins¹, has been marked for eventual extinction by many geneticists. And yet, without it, and the male-specific proteins for which it codes (the majority of which are designated for reproduction), men would cease to exist.

All humans contain 23 pairs of chromosomes, totaling 46 in all. Females carry a full complement of 22 autosomal (non-sex) chromosome pairs, plus a pair of X sex chromosomes. Males also carry the 22 autosomal pairs, plus a single X and a single Y sex chromosome for the 23^rd pair. The X is equivalent in size to many of the other autosomal chromosomes and, in the female, to the other X sex chromosome. The Y chromosome is much smaller than the other autosomal chromosomes, and certainly much smaller than the X.

During the production of sex cells such as sperm and ova, these 23 chromosomal pairs match up and exchange genetic elements with each other. Alleles, which are the different forms that genes can take, are swapped between chromosome "twins". Bad alleles are swapped for better ones, or vice versa. In the end, once this gene shuffling exercise is over, all the chromosome partners end up with a completely new combination of genetic alleles -except for one particular pair. The Y chromosome has no identical partner with which to align: its closest match is the much larger X chromosome. Additionally, the X and the Y do not contain alleles of the same genes, so there is not much to swap. The only regions that do any meaningful exchange are the ones located at the very ends (telomeres) of the X and the Y, and they do not contain much useful information anyway. The remaining 95% of the Y chromosome does not recombine with the X chromosome.