What stops humans from growing back fingers or arms or legs?
In: Biology
The human body doesn’t have a mechanism to see that something is missing. After we’ve developed we have instructions to continue growth for a while. We do have mechanisms for sensing and repairing damage but it is highly localized and more along the lines of ‘SEAL THE BREACH’ than ‘restore to factory spec’.
In homo sapiens (and quite a bit down our branch of the tree of life) there wasn’t really an evolutionary pressure to have this ability and I suspect that somewhere on the tree, some of the ‘tools’ needed to fulfill such a function (like keeping stem cells active for our whole lives) may have even proved to be a liability. It may have carried increase risk of cancers, it may have raised the ‘cost’ of our metabolism.
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