Over the last 300 years, scientists estimate that more than 150 vertebrate species have become extinct. There was the dodo, the Tasmanian tiger, and most recently the black-horned rhino. Now, according to researchers at Australian National University, we may have another, more prominent species to add to the list: men. Professor Jenny Graves theorizes that within the next 10,000 years we could see the end of the Y chromosome, and with it, men as we know it. For some, this may be comforting. Others, with a more invested interest, are slightly more apprehensive. Since this theory is still being flushed out and argued within the scientific community, an examination of both sides of this debate seems relevant. To better understand the possible extinction of men, we will first examine the background behind the theory, next, discuss the theories and
counter theories themselves, before finally, looking at some implications of these ideas, to see what kind of world we would have if there really were no good men out there.
The actual theory of the death of the Y chromosome has been around for a few years now, but biology and genetics professor Jenny Graves of the Australian National University has devised her own version of this theory which is turning heads in the scientific community. Through looking at the genomes of numerous marsupials and other mammals, she has found that the Y chromosome has steadily been losing some of its girth over the course of our evolution.
But before we get too deep into the theory we need a little refresher course on genetics. According to Genetics for Dummies, (it’s a real source. Google it yourself) every person comes complete with twenty four pairs of chromosomes. These pairs account for much of what makes us up, from the everyday things like hair and eye color, to sometimes more serious disorders like risk factors for cancer and alcoholism. In each of these 46 chromosomes, there are thousands of actual genes. Luckily for us, on this topic there’s only two that are really important: X and Y. These are the two chromosomes that are the determining factor of a person’s sex. If you get two X’s you’re a girl, with an X and a Y, you’re a boy.
It is here that the battle of the sexes is being waged. Females have an early advantage in this battle. With two X chromosomes they have the opportunity to weed out negative mutations that build up over a species’ history. Simply explained, any negative genes on one X can be trumped by well-functioning genes on the second. Males do not get this advantage. With only one Y, mutations have been building up for a few hundred thousand years. And that leads us to where we are today, with a shrinking Y chromosome. According to ABC Science On line of June 20, 2003, the Y chromosome has dwindled to only 45- 78 working genes. That, compared to the X, tipping the scales at a whopping 1,078 genes, leaves the Y on a perilous path.
Grave’s theory comes about from her study of Australian marsupials. According to the New Scientist of August 24, 2002, some 100 million years ago, the mammalian Y chromosome gained around 500 genes when another chromosome combined with what is now the Y. As this event was prior to most species specific deviations, some Australian marsupials, cut off from most of their mammalian kin, didn’t receive the booster and are now down to only 7 genes on their Y chromosome. Studying some of these species, Graves uncovered the massive genetic disparity between the X and Y chromosomes.
So now that we have genetics understood, it’s time to look at the theories and counter theories that have developed.
The primary theory regarding the extinction of the Y chromosome discusses a major problem facing the Y chromosome is the number of times it gets replicated every day. A female in her lifetime will produce somewhere around 4,000 eggs. Each of which has 23 chromosomes which can all mutate. However, each male makes hundreds of thousands of sperm every day. Again, each sperm contains 23 chromosomes. Every time one of these cells is created there is another chance for mutation. And, according to Professor Aitkin of the University of Newcastle in Australia, as a 35 year old male will have produced 350 times more chromosomal copies than a female the same age, men have a greatly increased chance of genetic mutation. So with all these extra mutations on the Y chromosome, it is quickly losing its mass and becoming dysfunctional. Using this data, Graves projects that over the next ten thousand year the Y chromosome will become more and more dysfunctional, until men become completely infertile. This would leave women little chance for reproduction; thereby leading to the end of the human race.
But Dr. David Page of MIT sees things a bit differently. Page and a team of researchers have for the first time completely mapped the genetic sequence of the human Y chromosome. And with this map, they argue that the Y chromosome may have a mechanism of self preservation. According to the Orlando Sentinel from June 18, 2003, the Y chromosome may save itself with the use of palindromes. It turns out that the genes on the Y chromosome are arranged in the same way as the word racecar. For example, if a Y chromosome holds the genetic sequence “CAAC” then the opposite side of that double helix would contain the mirrored sequence “GTTG”. This works in the same way as backing up your hard drive on your computer. So if you get a corrupt file, mutation, there’s a fresh copy somewhere that can be accessed and eventually replace the defective genes. It is with this process that Page hopes the Y will eventually regain some of its lost genes and reverse the damage that it has sustained through the last few millennia.
A third theory relies on a concept known as XX-Men. No, not like those XX-Men. These ones have a much more mundane mutation. According to the Sinclair Murdoch Children’s Research Institute on August 10, 2006, 1 in every 150,000 men born have two X chromosomes, however, they are also born sterile. The hope is that somewhere in the next 10,000 years the male’s increased chance of mutation will create a mutation on the second X gene of these new males that will allow for them to also reproduce. A problem with this theory is that it relies completely on chance to save all of humanity.
A variation on the XX-men theory is called migration; something we already see occurring. In 10% of XX-men there are some parts of the Y latched onto one of their X’s. So far it’s not enough to make them fertile, but it is proof of the concept. As seen in the Futurist of March/April 2005, we may already have an example of this. In 1995, scientists discovered that the European Mole Vole has no Y chromosome in its males. The parts of their former Y chromosome that were responsible for the reproduction process somehow shifted onto another chromosome that still allowed for both males and females. Hopefully, the human species will adapt in a similar fashion to the mole vole, without moving to underground burrows.
Having examined the science behind the theories, as well as the theory and some counter-theories, we’ll now look at some implications of such research.
To begin, the possible end of men, and humanity with it, leaves us with some troubling visions of the future. However, as we’ve seen time and time again, humanity’s use of technology and science could come through to save the day. With the recent announcement of possible reproduction using two eggs, we have to ask ourselves: is the end of the Y really that troubling at all? In 10,000 years, it is entirely possible that science could develop a technique for genetically engineering a new Y chromosome. As a society, we have looked to science to get us out of many of the bad hands that nature has dealt us. From the polio vaccine to penicillin, human beings have relied on scientific discovery. However, when we’re facing a possibility as overwhelming as human extinction, can we really afford to rely on the hope that science will once again see us through? Or will we as human beings be forced to finally admit that we are, after all, just human beings?
Which raises the next point: through all of our posturing and presupposed dominance over the other life on this earth, the possible natural extinction of the Y chromosome holds a sobering reminder of our true place. With some scientists estimating that the extinction rate on this planet has increased 1000% since the beginning of colonization, as a species, we must account for our actions as we look into our own possible demise. We have contorted and twisted the natural order of things for centuries, but in the end, nature laughs last. Despite all of our technology, and all of our progress, human beings might still have to answer to natural selection.
Today, we have examined the possible end of the Y chromosome and human kind along with it, by first, looking at the science behind the theory, then exploring some of the theories and counter-theories, before finally, looking at some of the implications of these ideas.
The human race has come a long way since our humble beginnings. Whether science will come to our rescue, or nature will reign supreme, is something only the future will know. But in the meantime, we should all learn to appreciate what we still have. Men.
