Why do we have hair in some parts of the body and in others not? BBC News

Have you ever wondered why you have hair on your legs but not on the soles of your feet?

Or why do we have a lot of hair on our head, but not a single hair on our palms?

For years, the question has been an open question for doctors, researchers and other specialists in the complex machinery of the human body.

For decades, science has confined itself to considering that it was an evolutionary function of some animals, but the physiological explanation of how it is produced does not was until recently not a question.

Scientists from the University of Pennsylvania's Faculty of Medicine have been investigating this "mystery" for years and now claim to have discovered an answer.

The study published in the journal Cell Reports states that "the culprit" of which no we obtain hair in certain parts of our body is a special type of molecule for more signal, a protein.

According to the researchers, this is Dickkopf 2 (DKK2), which blocks "WNT signaling pathways", cellular channels that, among other things, are responsible for triggering growth hair.

"In this study, we show that skin in hairless regions naturally produces an inhibitor that prevents TNOs from doing their job," he told Newsweek Sarah E. Millar, one of the authors of the research.

"We know that WNT signaling is essential for the development of hair follicles, blocking it causes a hairless skin and activating it causes the formation of more hair," he said.

But why do some animals have hair on most bodies and others not?

What will evolve

The study suggests that it is, as has been felt for years, an evolutionary adaptation.

The investigation considers that some animals evolved to produce DKK2 in parts of their bodies in order to help them survive their environment better

Thus, for example, one hand without hair would be more useful for holding instruments or other tasks, while the absence of villi on the soles of the feet would help to walk better.

On the other hand, in cold climates, better if they are coated, as in the case of polar bears.

To reach these conclusions, the team badyzed the skin of the legs. a mouse (which, like humans, do not have hair on their plants) and compare them to other animals that have them, such as rabbits.

When comparing levels of DKK2 between the two species, they found that protein was significantly lower in the skin of animals carrying hair on the soles of their legs

. of the molecule was much higher in areas where hairs do not grow than in hairier ones.

The study indicates that it is not that there is no WNT signaling pathway in these areas, but that the protein blocks them.

Researchers now hope this discovery can be used for future research. on hair growth, to treat certain diseases or for future treatments in people who have suffered serious burns or accidents.