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

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 the head, but not a single hair on the palms of the hands?

The issue has been an unresolved issue for years for doctors, researchers and other specialists in the complex machinery of the human body.

• Why do pubic hair grow?
• The mistake of shaving your head to avoid becoming bald and other myths about hair loss

For decades, science has been limited to considering that it was a matter of evolutionary trait of some animals, but the physiological explanation of how it is produced was until recently a question.

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

The study, published in the journal Cell reports, indicates that "the culprit" of not We get hair in certain areas 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 the "WNT signaling pathways", cellular channels that are among other things responsible for triggering hair growth.

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

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

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

Things of evolution

The study suggests that it is, as is known for years, an evolutionary adaptation.

Research considers that some animals have evolved to produce DKK2 in some parts of their bodies help them survive better in their environment.

Thus, for example, a hairless hand would be more useful for holding instruments or other tasks, while the absence of villi on the soles of the feet would help better walk.

In cold climates, however, it would be better to cover them, as in the case of polar bears.

To reach these conclusions, the team analyzed the skin of the paws of a mouse (which, like humans, did not have hair on their plants) and compared it to other animals, such as rabbits.

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

Meanwhile, the level of the molecule was much higher in areas where the hair does not grow than in the most hairy areas.

The study indicates that it is not in these areas that there are no signaling pathways for TN-O, hair producers, but that the protein blocks them.

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

You can now receive notifications from BBC News World. Download the new version of our application and activate it to not miss our best content.

• Do you already know our YouTube channel? Subscribe!