Ten thousand years ago, the average human life lasted just over 30 years. One hundred years ago that number was up to 50 years.
If you were born in the last few decades in the developed world, then you life expectancy is 80 years, but that is, of course, assuming that no major breakthroughs happened during your lifetime that can slow the process of ageing and that may be a very bad assumption.
Ageing is not recognised as a disease, there is plenty of diseases that we do acknowledge like diabetes, heart disease, Alzheimer’s and at their core ageing may be responsible for all of them, and yet ageing seems natural, because it is something that we do from birth and for a while it makes us better, bigger, stronger, faster, more intelligent, but then at some point in your life it reverses and ageing makes our bodies decay. But why is that?Why do we have to age? Why do our bodies have to decay?
Scientists are now realising, there is a fundamental cellular mechanism at the heart of ageing. A key discovery was made by a biologist named Hayflick. He was studying normal human cells, he found that they can only divide a finite number of times, on average it is about 50, beyond that the cells become ‘’senescent’’, which means its’an aged cell that can divide no longer lives for a little while but it’s the accumulation of the ‘’senescent’’ cells in our bodies that lead to ageing on the macroscopic scale. Human cells have a little timer inside them that tells them when to stop dividing. But how do they know? And what is that timer?
Inside the nucleus of a cell, our genes are arranged along twisted, double-stranded molecules of DNA called chromosomes. At the ends of the chromosomes are stretches of DNA called telomeres, which protect our genetic data, make it possible for cells to divide, and hold some secrets to how we age and get cancer.
Telomeres have been compared with the plastic tips on shoelaces because they keep chromosome ends from fraying and sticking to each other, which would destroy or scramble an organism’s genetic information.
Yet, each time a cell divides, the telomeres get shorter. When they get too short, the cell can no longer divide; it becomes inactive or “senescent” or it dies. This shortening process is associated with ageing, cancer, and a higher risk of death. So telomeres also have been compared with a bomb fuse.
There is one animal that doesn’t seem to age, and that is the lobster. Lobster just gets bigger, it doesn’t get weaker and its chromosomes don’t change, it has long telomeres that do not shorten, so it doesn’t die from biological ageing (known as biological immortality). So how can we be more like a lobster?
Cancer cells have really long telomeres, and they can divide indefinitely, and that is the problem with cancer – it won’t stop and it won’t die, so in a way cancer is the immortal cell living within us. If we were immortal wouldn’t we be equivalent of cancer for the planet?
Over the past hundred years developments in medicine have increased human life span more than we could ever imagine and we could only expect that the next hundred years will bring similarly incredible results, we can’t be sure where or how they will take place but you can bet that your life expectancy today will not be the actual age at what you die.