[Op-Ed] The End of the Y Chromosome?

The X chromosome was discovered by German biologist Hermann Henking in 1890. Though unaware that it carried “feminine characteristics,” he called the chromosome extracted from the testes of a Pyrrhocoris X chromosome because of its mysterious and extraordinary qualities, not because of its shape as many believe. It seems reasonable that the chromosome that defines femininity bears such a name given that women are often a mystery.

In 1905, Nettie Stevens of Bryn Mawr College in Pennsylvania discovered the Y chromosome. Dedicating her life to studying the mealworm Tenebrio, she found that while the female insects had 20 normal-sized chromosomes, their male counterparts only had 19 and one very small chromosome. She discovered the counterpart to the X chromosome. It seems ironic that the X chromosome was discovered by a man while the Y chromosome was identified by a woman.

Scientists say the X and Y chromosomes originally bore the same shape. They parted when the Y chromosome gained the gene that determines sex. After separation, the Y chromosome could no longer exchange genes with its counterparts, and it became impossible for them to co-exist with other Y chromosomes. While the Y chromosome was withering away, the X chromosome began to enjoy life away from its counterpart. The X chromosome can co-exist and exchange genes with the same chromosomes, which prevent them from degenerating like the Y chromosome.

In its recent paper “PLoS Genetics,” a research team at Penn State University said the Y chromosome is in danger of extinction because of its continuous degeneration. The number of genes for Y chromosomes, which was initially equal to that of the X chromosomes, has declined to 80. In contrast, there are 1,100 genes in X chromosomes. Despite a potential fallacy in linking the degeneration of the Y chromosome to the trend of “men’s feminization,” the results have other implications. University of Cambridge anatomist David Bainbridge said the X chromosome carries good social skills. Chromosomes and people alike exist in connection with others; it all boils down to forming relationships.

Editorial Writer Chung Sung-hee (shchung@donga.com)