why do organic bodies degrade over time and not continually regenerate?
In: Biology
There are some relatively simple organisms, like earthworms, whose physiology is very strictly defined by their genes. So if they’re damaged severely to the point of being torn in half, as long as the remaining sections can stay alive, they can regrow. But they don’t have a brain and their nervous systems are very simple.
But even then, cells have a built-in limitation. The are sections of DNA at the ‘ends’ of all our chromosomes, called telomeres, that become shorter and shorter every time the chromosome duplicates. Eventually they wear off completely, and the chromosome starts to break apart and lose the informative sections. The result is that most cells are able to make only a limited number of copies of themselves before breaking down.
There are enzymes that are capable of rebuilding the telomeres. Our limited lifespans are a feature of our design, not merely an accidental deficiency; it’s our nature to wear out and die. It’s thought this is to give our offspring a better chance to survive in a world with limited resources.
They do continually regenerate, but to do so perfectly without error, and while correcting all kinds of problems that slowly get introduced… that’s difficult! You need different processes to heal different kinds of problems. Then you’ve introduce complexity, so that too needs controls and processes so it can keep working (and not break in a dangerous way)
So the longer an organism is meant to last, the better it handles all these things (evolutionary pressure). The simpler the organism, the better it handles this (needs less complicated systems of maintenance)
Eg: Cancer is cells trying to continually regenerate, and eventually breaking and going out of control. We have a special process in our body to capture and kill cells which are going cancerous, and it’s not a perfect process. So our body actually constantly “cures” cancer, until some appears it cannot handle.
– if we change it to be more sensitive and attack the ones it lets thru? You get the body attacking normal body cells “just in case”. Autoimmune
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