Could We Live Forever? | Earth Science

A great man once said, who wants to live forever? Well, judging by the amount of money that's been invested in prolonging life, I'd say that quite a few people do, or at least the very rich ones. But despite medical advances over the last century or so, leading to a creeping increase in life expectancy, there does seem to be a limit to the length of a human life of around 120 years. But is that the best that we could do? Could we live forever? Well, gerontologist Aubrey de Grey certainly thinks so. In fact, he thinks that the first person to achieve immortality is already alive today. The theory goes that if we can find a way to extend our lives by a few decades, then in those decades, new advances can grant us even more longevity, in which time technology will have advanced to add a few more years, and so on. Achieving this longevity escape velocity, in which life expectancy is extended faster than time is passing, is the holy grail of all ageing research. But what is ageing? We might see it as wrinkles, grey hair, stiff joints and mental decline, but inside our bodies, there are more subtle processes at work. There's DNA methylation, extra bits of junk that our genetic molecules accumulate over time, which interfere with how our genes function. Plus, over the years, our genetic code can become damaged, thanks to mutations or mistakes made when the DNA is copied, or by collisions with reactive free radical molecules. And then there's our telomeres, the protective caps at the end of all our chromosomes, which become smaller every time the cell and the chromosomes divide. All these factors and more contribute to something called cell senescence, the ageing and deterioration of cells that produces the tangible evidence of old age. So, to stop ageing, we need to find a fix for cell senescence, and one potential solution that sounds like something straight out of your favourite vampire romance, assuming you have one, is to replace your old blood with new. It was way back in the 1800s that scientists first started experimenting with parabiosis, linking two animals together so they share a circulatory system, with some intriguingly positive results. By joining the circulatory system of an old mouse to that of a young mouse, scientists have noted that in the heart, brain, muscles and almost every other tissue examined, the blood of the young mice seems to bring new life to ageing organs, making old mice stronger, smarter and healthier. It even makes fur shinier. Although we're still not entirely sure what it is in young blood that's doing the trick, evidence points to proteins that build up in our blood as we get older. Too many of these proteins can start to hamper the growth and maintenance of body tissues, and replacing with young blood massively dilutes their concentration. This promising finding suggests that we may be able to keep our bodies up and running by simply filtering out the proteins, rather than needing to undergo transfusions or running around sinking our teeth into the necks of teenagers. Scientists are also exploring medicinal routes to eternal life, or at least ways of extending it a bit for now. Rapamycin, which is normally used in organ transplants and to treat rare cancers, was found to extend a mouse's life by up to 25%. If it works in humans, that could be the equivalent of adding an extra 30 years of life or so, raising the longevity ceiling to around 150. And the diabetes drug metformin seems to help the body run smoothly for longer in life. Metformin increases the number of oxygen molecules released into a cell, which appears to boost robustness and longevity. And at a cost of only around 10 pence per day, it could be a very affordable way of adding on those extra years. And finally, some futuristic gene therapies are claiming to be able to rewind the biological clock present in every cell. Born of a technique to turn specialised body cells back into stem cells, scientists are attempting to partially reset them, returning them to a younger state, but not letting them completely lose their function. It's still in experimental stages and apparently not ready to be applied in humans. However, the researchers expect that clinical trials are a decade away or so. But if other techniques can keep us going for those years, then that longevity escape velocity might still be achievable. But what happens if and when we do find that fountain of youth so that our lives span centuries and millennia rather than decades? Well, we can forget about retiring at 65 for a start. We'll be fit and healthier for much, much longer, so we'll be able to stay and work indefinitely. Doesn't sound like much fun, but we'll need it if we're going to support ourselves for hundreds of extra years. But with supercentenarians keeping their jobs for much longer, that leaves little employment and earning potential for young people. Never mind the worries of overpopulation and housing in a world where births continue apace and death is rare. Clearly, living forever isn't the gateway to utopia that we might expect. So maybe immortality isn't the answer, but in the short term, it can't harm to stay healthier for longer, putting off those age-related diseases like Alzheimer's and heart disease. And for that, you don't need a blood transfusion or gene therapy. Just some simple changes in lifestyle should suffice. So eat well, sleep well, and exercise regularly. So would you want to live forever? What length would you go to to cheat death, and what would you do with all that extra time? 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