my question is, why do we have scars. it may sound simple(minded), but it requires a better answer
than, “because we run into stuff.”
consider: the human body constantly recycles its cells. i’ve heard that roughly every seven years that
process replaces every cell in our bodies with new ones created from material in the food we eat. to
pull off this trick our bodies rely on DNA to act as a blueprint for what new cells they build and
how to arrange those cells into an organism. the reason we don’t change from an ape to an octopus
every seven years is that the body only builds what’s in the plans. so why do scars persist if they
aren’t in our DNA? and for that matter, why don’t people who have lost an arm build a new one,
since that is in the plans?
Scar tissue is what happens when you make your body regenerate a lot of cells at once. Cancer is another example.
Basically, your body can knit together things that are still there, and to a lesser degree replace some missing cells slowly, but for the most part regeneration of exact body parts is an ability that gets lost at about the same level of evolution that things develop central nervous systems.
Interesting. Sounds like maybe scars become a part of the plan once their instituted. And since the rebuilding (replacing?) that you are talking about is at such a slow pace, that the loss of a limb would not be remembered and the cells would only replace what exists now. Does that make sense?
Oh well, I have an inch-long semi-fat daddy scar on my cheak that I’ve been told looks like it’s suppose to be there. Kinda makes me feel like my old GI Joe (and yeah, I got the Kung-Fu Grip, too). GO SCARS!!! Does that make sense?
The thing is, the original growth and repair growth are very very different processes, mediated by different signals and carried out by different cell types. Scars happen because the first cells to respond to an injury are the clotters. Their job is to make proteins that will close off the wound. Etc, etc, etc. Sorry. I just realized I’m too tired to try and explain the whole process, even if I could remember all the details.
Suffice it to say, they’re very different processes. Your DNA contains instructions for both, under the control of different signals.
Though I’m not sure of the mechanisms involved in retaining scar tissue, it does seem to depend on the seriousness/nature of the scar and what you did to it (picking, medicating, etc) - which is complicated in it’s self. I’ve had a little cat-scratch like scar on my arm from a tree branch since I was a kid; and a little scar on my shoulder from when I had chicken pox at around 12. Neither are going anywhere, and I’ll probably have them for life. OTOH, I got a large 1.5" diameter burn on my leg from a motorcylc exhaust pipe in Asia 3 years ago; very ugly at the time and left me a lovely scar for a while…it’s completely disappeared now. (damn!! now how can I convince anybody that I was an outlaw biker-dude in the far-east?:D)