It's not every day that researchers learn something completely new about how the human body works.
To be sure, researchers already knew that human beings have a unique kind of sweat gland, not found in any other animal.
But they didn't know everything those sweat glands do.
Laure Rittié of the University of Michigan says it was assumed that our hair follicles create new skin cells to heal wounds - because that's how rodents and pigs do it.
But she says that brought up questions, like, why are we able to heal wounds on our palms and feet - where there are no hair follicles?
To solve the mystery, Rittié and her colleagues used special lasers to make tiny, thin cuts in the skin of volunteers, and analyzed where those new skin cells forming underneath the scab were coming from.
And surprise! "The new skin cells are .... coming from the sweat glands," says Rittié -- not the hair follicles.
Rittié says our unique sweat glands likely evolved as we lost many of our hair follicles, and began running long distances to track prey.
The glands may have had to take over the wound-healing function of the hair follicles.
The discovery could lead to treatments to help sweat glands heal wounds better and faster.
"We now have a target for designing new therapies to actually try to help the sweat glands produce those new skin cells that are necessary to close a wound."
Rittié says the skin is an understudied organ in medicine, and that's why this basic fact about the body was missed until now.