If we evolved from random combination of elements, why haven't we evolved to grow back amputated limbs?

We have. We lost that ability. Why is an interesting question, and I
think the answer is that it "costs" too much. As life gets more
complex, the repair systems need to be more sophisticated, and the
overhead involved in carrying around such a repair system makes those
individuals less likely to survive and reproduce. Ironic, isn't it.

Darwin cares not a whit for the individual.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
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