In school, the Y chromosome is taught as a symbol of masculinity, but it is becoming increasingly clear that the chromosome itself is not strong and enduring. The Y chromosome carries very few other genes and is the only chromosome not necessary for life — after all, women do not have one. Smithsonian Magazine writes that the Y chromosome has degenerated rapidly, which leaves women with two perfectly normal X chromosomes but males with an X and “shriveled Y.” If this degeneration continues at the same rate, the Y chromosome has just 4.6 million years left before it disappears completely. This might sound like a long time, but life on Earth has existed for 3.5 billion years. The early “proto-Y” chromosome was originally the same size as the X chromosome and carried all the same genes. But the Y chromosomes have a fundamental flaw: they are only ever present as a single copy, passed from fathers to their sons. This means that the genes on the Y chromosome cannot undergo genetic recombination, which causes degeneration over time. The science community is currently divided on whether or not the chromosome will fully disappear. If it does fully disappear, that does not mean that males will be wiped out too. Males and females are both still needed for reproduction. The SRY “master switch” gene that determines genetic maleness has moved to a different chromosome, so species don’t need a Y chromosome to produce males.
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