If all human cells replace themselves every 7 years, why can scars remain on you body your entire life?

Question

If all human cells replace themselves every 7 years, why can scars remain on you body your entire life?

In: Biology

Answer 1

They don’t. You might generate a number of new cells equal to the number of cells that make up a whole body every ~7 years, but the vast, vast majority of that is high-turnover cells like skin, GI lining, RBCs, neutrophils and so on, while some barely or don’t replicate at all.

Also, scars are like a quick patch-up job. As far as evolution is concerned, it’s a very efficient solution to major damage, so has stuck around.