Will Men Become Extinct Due to the Disappearance of the Y Chromosome?
Scientists' predictions about the potential disappearance of the Y chromosome and, consequently, men, have sparked a scientific debate. Evolutionary biologist Jenny Graves, whose initial calculations two decades ago caused a global sensation, confirmed that this is merely one possible scenario. She emphasized that the disappearance of the Y chromosome does not mean the extinction of males, as some media outlets had claimed, but is just a potential hypothesis.
Historically, the Y chromosome was an exact copy of the X chromosome and contained about 800 genes. However, by taking on the role of sex determination, it lost the ability to exchange genes with the X chromosome, making it vulnerable to information loss. Over the past 300 million years, it has lost 97% of its original genes, retaining only 3%. Despite this, Graves notes that the loss of genes did not occur at a constant rate, and any estimates of its complete disappearance are merely speculative.
Two main schools of thought exist in the scientific community. The school of «continuous degradation», represented by Graves, believes the Y chromosome continues to slowly shrink, and its replacement is only a matter of time. An example of this is certain species, such as mole voles of the genus Ellobius, which lack a Y chromosome entirely, and the genes responsible for sex determination have moved to other chromosomes. Graves describes the Y chromosome as a «genetic waste dump» due to the numerous inefficient repetitive sequences it contains.
In contrast, the «long-term stability» school, led by the Massachusetts Institute of Technology (MIT), argues that the Y chromosome has stabilized and has lost almost no components in the last 25 million years. They suggest that a new, more efficient version of the gene determining male sex may have emerged.
As researcher Jean Hughes pointed out, this debate reflects two different visions of evolution itself: is stability the norm, and is constant change the fate of genes? Graves summarized the situation: «The evolutionary history of the Y chromosome may lead to its extinction... or to its stabilization. The possibilities are open forever».
Ultimately, as Graves herself said: «It amazes me that anyone fears the extinction of men in 6 million years, when we, as humanity, cannot even guarantee our survival for the next hundred years!»
