Question: how would humans in the future be able to be able to live up until 400 years old or older

Kim Liu answered on 30 Apr 2020: last edited 30 Apr 2020 9:57 am

Thanks for this awesome question; it’s something I’ve often wondered about myself! Life in general is limited by a lot of factors, but I’m going to assume that all external, non-biological factors are already solved, so we have enough food and space, and we won’t be killed by accidents, war or natural disasters in the meantime! Also, I’m going to assume that we’re going to be still young and enjoying living up to 400 yrs old!
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Aging is a very complex area of research because it is very hard to collect reliable data, but most theories point towards issues with DNA and genes being the cause of aging. I’m going to focus on what I think is the most difficult challenge. Your DNA is being copied and duplicated all the time – that’s 6 billion letters to copy correctly every time a cell wants to divide. Imagine copying the whole Harry Potter series (1 million words) constantly – the cells is very, very good at doing this accurately, but mutations happen all the time. Luckily, most mistakes don’t cause trouble because cells will automatically kill themselves if they spot serious mutations, but by the time you’re living to around 100 years old it becomes more and more likely a serious mistake will not get noticed. This is a reason why cancer is so common – eventually, cells can get mistakes which are not fixed and start damaging their body.
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Therefore, to gain longer lifespans we’d need to have a way of accurately fixing our DNA using genetic engineering all the time. We have some good ways of editing DNA (have you heard of CRISPR?), but turn these into a medicine is very hard! It’s not too crazy to imagine nanoscale machines which can carry these DNA editing machines around your body to help correct these mistakes. Another solution to this problem might be to use an external, personal source of stem cells (cells which, roughly, can turn into any other cell) to replenish our own cells and DNA. I am quite confident humans of the future will be able to work out some way of fixing our DNA, and if they do manage to live much longer this will be an important part of the solution.

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Hope this makes sense ~ Let me know if there’s more you want to ask! After this – there are some more issues that I can leave you with to think about – leave a comment if you want to know more about any of them: The ends of chromosomes are always worn down when they are copied, and their caps called telomeres need to be replenished, chemical markers on DNA known as methylation probably also need to be monitored and reset periodically, and regulation of autophagy, a process which cleans cells of unnecessary or dysfunctional components.