The sex of human babies, like other mammals, is determined by a gene on the Y chromosome. But the human Y chromosome is slowly disappearing and might be gone in a few million years, which could lead to our extinction unless we develop a new way to determine sex.
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In humans, females have two X chromosomes, while males have one X and one Y chromosome. The Y chromosome has fewer genes but carries an important one called SRY, which starts the development of male features in an embryo.
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Over time, the Y chromosome has been losing its genes. It once had many more, but now it’s down to just 55. At this rate, it might lose the rest in about 11 million years. Scientists are still debating exactly when, but the loss of the Y chromosome seems likely.
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Some rodents, like mole voles in Eastern Europe and spiny rats in Japan, have already lost their Y chromosome and the SRY gene but are still able to survive. The spiny rat has moved most of its Y chromosome genes to other chromosomes and developed a new way to determine sex.
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The possible loss of the human Y chromosome raises concerns about our future. Unlike some species, humans can’t reproduce without males because we need certain genes that only come from the father.
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But, there’s hope that humans might evolve a new way to determine sex, just like the spiny rats did.
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However, this change carries risks. If different regions develop distinct sex-determining systems, it could result in new human species, each separated by these differences. In 11 million years, we might see no humans or several species, each with its own way of determining sex.
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