When I get a minor cut on my hand or arm, the wound usually heals completely within a week or two. On the leg, the same damage can take more than a month before it’s repaired. The same seems to be true for my wife, and I suspect, most people.
Why should this be so? In modern times, we get far fewer injuries on our legs than our arms, so it’s really not a big issue, but our ancestors would surely have gotten a lot of minor leg damage pursuing the wild rhinocerous, naked through the cutgrass fields of Africa. Were prehistoric peoples legs a mass of scars and cuts, or is the rate at which a particular part of the human integument heals affected by how often that part gets wounded? Or is there some other explanation that I’m not seeing here?
Poorly healing or slow healing leg injuries can sometimes be a symptom of diabetes. You may want to check this with your doctor.
I expect arms get a slightly better blood supply than the legs, if for no other reason than they are closer to the heart and lungs. As time goes on and the person ages this different can become greater. Add in something like diabetes or narrowing of the arteries and the problem only increases.
Not a concrete cite, but this seems to indicate that Squink’s anecdotal experience (which also coincides with mine) is correct:
While the concerns over disease states and the horror of aging are appreciated, I’m really wondering about the relative rate of healing on the arms vs legs of say a healthy 20 year old.
Do legs heal faster from minor injuries if they get injured more often?
If not, why wasn’t rapid leg healing selected for as strongly as rapid arm healing from among our ancestors?
I’m looking for a bit of a physiological or evolutionary explanation for the phenomena.
-Thanks neuroman, that’s a start.
Fresh chips of flint can be razor sharp - it may be faster healing in hands, arms and trunks was selected because flint knapping to create tools made such injuries far more likely on the upper body rather than the lower. Also, with hands being used to manipulate various things, including messy butchery of carrion as well as fresh-killed meat, the risk of infection from hand/arm cuts might have been higher than from leg cuts - again, that would favor faster upper limb healing.
Just wild speculation, and off the top of my head.
At the derm office I work in, we do biopsies all day long. The doctors tell people that ones on the legs will heal much more slowly than others. Even up to 8 weeks.
This is due to less circulation in the legs. It’s normal even for healthy, young people, but gets more pronounced with age as the skin loses it’s integrity, or if you’re on medications that do the same.