system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If our cells are constantly regenerating, why do we have permanent scars?
gpt
Humans are, as an animal, incredibly difficult to bring down. We can walk off injuries that would kill or cripple most mammals.

One of the things that helps us do this is our hyperactive healing process. Put simply, we heal fast. *Really* fast. The downside of that is scarring. We scar because instead of healing nice and neatly our bodies are programmed to do it quick and dirty. Scar tissue isn't pretty, but it's the fastest way to close a wound.