By: PENNY MACIAS
The male sex chromosone, which is very unstable, has led scientists to find that is it slowly disappearing. Professor Jennifer Graves of Australian National University has previously suggested the Y chromosome may become extinct in as little as five million years’ time, based on the rate at which genes are disappearing from the chromosome. But, without the Y chromosome, how will we continue the human race?
In fact, women carry sperm cells in their bone marrow, so they don’t necessarily need males to reproduce. Their offspring would always be daughters, though, because sperm made from a female cell would always carry an X instead of a Y chromosome. While this may sound far-fetched, the animal kingdom throws up some scary precedents. Whiptail lizards are a case in point: they have already evolved into a self-sustaining species composed entirely of females. Also, women live longer than men; 73.5 years vs. 68.5 years on average. There is an ongoing debate about the extinction of men, although it’s not going to happen in the near future. However, others suggest that this loss of the Y chromosome won’t lead to the loss of men altogether.
For whoever was worried, or excited about the extinction of men, ever since this theory came up there have been many who have challenged it. Jennifer Hughes and colleagues at the Whitehead Institute in Cambridge, Massachusetts, have sought to determine whether rumours of the Y chromosome’s demise have been exaggerated. In a paper by Nature in 2005, they compared the human Y chromosome with that of the chimpanzee, whose lineage diverged from that of humans about six million years ago.
The conclusion from these comparative studies is that genetic decay has in recent history been minimal, with the human chromosome having lost no further genes in the last six million years, and only one in the last 25 million years. Hughes says, “The Y is not going anywhere and gene loss has probably come to a halt. We can’t rule out the possibility it could happen another time, but the genes which are left on the Y are here to stay. They apparently serve some critical function which we don’t know much about yet, but the genes are being preserved pretty well by natural selection.” So, there is a chance that the Y chromosome won’t go extinct fully.
Scientists suggest that the Y chromosome has inbuilt mechanisms that will prevent it from losing all of its genetic material. Due to the presence of many copies of the same gene on the Y chromosome, these copies will ensure no gene is completely lost or degraded. Fortunately, or unfortunately, men may not go extinct!