system
Given the following post, respond as if you're commenting on Reddit:
human
What limits the speed of healing?

I was thinking about this earlier... it seems reasonable to assume that a living thing that was able to heal faster than its competition would have a definite Darwinian advantage, but it seems as though most animals have sort of plateaued at about the same place. For example if I get a small cut it will probably take a couple of days to heal, and it would probably take a cat or a cow or a platypus about the same amount of time. There's no animal I (that I know of) that would heal in seconds, for example. So what prevents this?

If I had to guess I'd say that fast healing would either use up energy too quickly to be viable, or that rapid cell multiplication like that would cause something like cancer or premature aging. But I am no scientician!
gpt
In a way it does happen fast! The most important part of fixing an injury would be to make sure you don't get any infections from it, and we do mount responses to that end in minutes (or maybe an hour or two) by clotting the wound, recruiting LOTS of immune cells and making sure that infectious agents don't enter and you don't loose blood.

But full healing is mechanistically very complex: you need to first clear all the cells that died, then make new cells in the same design as before, all the while making sure you don't loose any blood or get any infections. I'd say our bodies do a pretty amazing feat already, even the theoretically best possible levels!