Most of the body doesn't regenerate because there was not enough evolutionary pressure. Even with regeneration you could still easily die from some severe injury, blood loss or disease. While salamander regeneration is impressive, it has its limitations. For example, no known adult salamander can regenerate an entirely removed eye. Also if you chop a salamander, it will not regenerate like a Planarian worm, it will just die. And a fun fact, Axolotls can regrow a limb yet cannot regenerate an adult eye lens.
Also, although the article is mostly true, there are some inaccuracies:
>> Neurons and cardiac muscle cells don't reproduce after childhood
There is some evidence showing a slow cell turnover in cardiac muscle, estimated around ~1% per year in young adults, falling toward ~0.5% in older people. Most neurons don't regenerate, but there an evidence that some parts of the adult brain (such as hippocampus) still produce new neurons, although the number is very low.
Liver regeneration is not perfect either: <a href="https://www.youtube.com/watch?v=rOv7Sr3X-eo" rel="nofollow">https://www.youtube.com/watch?v=rOv7Sr3X-eo .
Getting "old" is a recent and tiny sliver of human evolution. It's only been the last 100 or so years that we've really started to push the boundaries of what the body is capable of and our biology has never really had a chance to deal with it and "develop" a solution.
This isn’t correct. For example, when Edmond Halley created the world’s first life table in the 1690s, he estimated that approximately 5% of his city’s adult population was >70. Getting old is not new.
senfiaj · · focus · HN ↗
Also, although the article is mostly true, there are some inaccuracies:
>> Neurons and cardiac muscle cells don't reproduce after childhood
There is some evidence showing a slow cell turnover in cardiac muscle, estimated around ~1% per year in young adults, falling toward ~0.5% in older people. Most neurons don't regenerate, but there an evidence that some parts of the adult brain (such as hippocampus) still produce new neurons, although the number is very low.
Liver regeneration is not perfect either: <a href="https://www.youtube.com/watch?v=rOv7Sr3X-eo" rel="nofollow">https://www.youtube.com/watch?v=rOv7Sr3X-eo .
werdnapk · · focus · HN ↗
cloudbonsai · · focus · HN ↗