I saw the movie Highlander and one question came to mind. After years of existing on this planet, and since humans have been able to develop better than other organisms, why haven't we been able to use natural selection and evolution to make us live forever.
Before I start to make you feel like you are the one with the problem, actually we all have the problem because there are no organisms on planet earth that can live forever or that has been living since as far back as we can calculate that still exists as a single organism and not evolutionary descendants.
Scientists were looking into hydra to see if it was possible that they do not die in an ideal environment although they live in freshwater of temperate and tropical regions and although they do not appear to age scientists needed to confirm this. This is because most of the cells in the body are made up of stem cells unlike we humans were we have specialized cells for different purposes such as skin cells, nerve cells, and so on but stem cells are undifferentiated cells. Stem Cells are responsible for making new cells and this is usually found in humans in embryonic state.
Back to the hydra, scientists wanted to confirm if they would grow old and remain that way without any deterioration, after monitoring the hydra for about 8 years, it was seen that hydra throughout the eight years didn't experience senescence as the stem cells in the body of the hydra replaced damaged cells with new stem cells. But in the wild, they die from predator and diseases.
Now we know that if the conditions were right, hydra might live forever but what about humans. When we get old, we are said to die of natural causes but then what is natural about death actually, it is the body part malfunctioning or getting infected with diseases. This is as a result of the body cells dividing and at such resulting in mistakes in genetic coding which causes mutations that can damage and kill the cells but in terrible cases, it can lead to tumors of the cells. Thanks to natural selection the Gene p53 helps us to prevent damaged cell from continually growing, rather they start to die.
If we are to look at the case of the hydra, then we would understand that even if our bodies were correcting themselves, there are chances of having diseases or other unnatural causes that increases our chances of dying. We do not have stem cells that would create new cells for us and so as we get old, our body do not find it productive to keep repairing and making us healthy. Our body has also programmed itself die so we do not overpopulate and become unable to survive.
Reference
https://www.sciencedaily.com/releases/2013/07/130731093255.htm
https://www.livescience.com/53178-hydra-may-live-forever.html
https://www.forbes.com/sites/quora/2016/07/13
https://www.medicaldaily.com/can-people-really-die-old-age-318528
https://www.nature.com/articles/6885440
https://www.livescience.com/53178-hydra-may-live-forever.html