A few days ago, my little girl, fresh out of the pool, came running to look for me, very worried because she was “pupae”. One fascinating thing about having young children is that they are a constant opportunity to rediscover the world we live in: the “pupae” were their wrinkled fingers. For me the explanation was clear: It’s something that happens when you spend a lot of time in the water, but at that moment I realized I didn’t know why.

After all, not all skin is wrinkled, no. It occurs only in the hands and feet. As Richard Gray puts it, “where once delicate spirals of a slightly rigid epidermis were visible, thick folds of flesh now appear more typical of the skin of a raisin”. The interesting thing is, if you’ll excuse me, as soon as you start researching the subject, you discover that there is a lot of material to cut.

A question with a long history. When scientific grounds are sought, the first studies to suspect a cat behind such a natural process date from 1935. By that time, the most common theory explained the issue as a clear consequence of water flooding the cells of the superficial layers. skin. C’mon, pure osmosis: water passing through cell membranes to balance concentrations on both sides. But it turned out that it wasn’t.

The first hint that this explanation doesn’t make sense came, curiously, from patients with median nerve injuries. To watch? So that her hands don’t get wrinkled. Considering everything the median nerve did, what seemed most obvious was that wrinkled hands were a matter of the sympathetic nervous system. Things got interesting.

looking for answer. So much so that in the 1970s this (putting your hands in hot water) started to be used to assess damage to the sympathetic nervous system – damage that could affect other things like the circulatory system. In-depth analyzes were not possible until 2003, but it was finally confirmed that wrinkling was associated with a significant decrease in blood flow. In fact, this effect can be achieved with anesthetics and other drugs that similarly affect the nervous system.

However, this is not an answer. That is, it does not explain why it happened. Neuroscientist and psychologist Nick Davis from Manchester Metropolitan University, who has studied this in detail, told the BBC that it all goes to show that our bodies are actively responding to being in the water; that is, “it may be giving us some advantage.”

hold me tight. The researchers’ explanation is actually quite intriguing. After many experiments, he concluded that “the wrinkles on our fingers can act like marks on rubbers or on the soles of shoes.” creases help drain water “by diverting it away from the point of contact between fingers and object.” Was it an adaptation to help us hold objects and wet surfaces?

But why? What is not clear is why our ancestors needed such a thing. It’s clear that walking on rocks and gripping branches in humid environments can help, but if that were the case, it would make sense to see a similar response in primates such as chimpanzees. Everything is said, something we cannot observe. Yes, a similar phenomenon was found in the famous Japanese macaques bathed in hot water, but only in them.

Some theorists have suggested that adaptation (at the dawn of the species) might help us consume shellfish and the like; The fact is, the fact that wrinkles are faster and more noticeable in fresh water means there’s no consensus. However, things would be simpler if the mysteries ended there: Things like why women get wrinkles longer than men or why psoriasis (or vitiligo) presents problems for this phenomenon remain important unknowns.

what do we know. But what is clear is that we experience a strange tension between the two sides of the spectrum: on the one hand, wrinkles increase support; on the other hand, they worsen sensitivity. Therefore, the sympathetic nervous system plays a key role in determining when, how and why we should move from one state to another. So we already know who to thank when we walk on slippery floors this summer without risking our lives.