Fingers quickly wrinkle from water. Why does the skin wrinkle from water? Potato decoction bath

Some parts of human skin that do not grow hair have a unique reaction to contact with water. Unlike the rest of the body, the skin on your fingers, toes, palms, and feet wrinkles when wet. Usually five minutes is enough for this.

But why do these areas of skin wrinkle? Some believe that this is a biochemical reaction, an osmotic process in which water draws out chemical substances from the skin, and as a result the skin dries out.

But scientists knew already a hundred years ago that this reaction was not explained by a simple reflex or the result of osmosis.

Surgeons have discovered that if certain nerves in the fingers are cut, the effect of wrinkled skin disappears. Therefore, this effect is associated with a functioning nervous system. As a result, this effect has even been proposed to be used as a test of the performance of the sympathetic nervous system in patients who do not respond to other influences.

So the scientific community has reached a consensus on this issue. But the reason why the effect of skin wrinkling when wet occurred during evolution, and whether it is associated with any adaptation mechanism, remains a matter of debate.

Neuroscientist Mark Changizi from 2AI Labs is confident that this effect is an adaptation. Let's remember the pattern on the surface of the tires. In dry weather, smooth tires grip the asphalt better, which is why racing cars have smooth tires without a pattern. But when driving in the rain, tires with a pattern become safer.

In 2011, Changizi and colleagues found evidence that wrinkled fingers actually work in a similar way to tires, moving water away from fingers and toes in wet conditions and allowing primates—specifically humans and macaques—to maintain a secure grip.

In other words, wrinkles that appear from exposure to water can be considered tiny systems for draining fluid. A river consists of streams flowing into it, and the areas of land between the streams are not connected to each other.

To test whether wrinkled skin on fingers resembled a branching river system, Changizi and his team studied 28 photographs of human fingers. They found that the pattern of wrinkled fingers is an inverted copy of fluvial systems - in it, raised areas are connected to each other, and there are unconnected tubules between them.

At the same time, the rises are not located anyhow; their drawing is quite meaningful. Rivers accumulate water, and the tubules on the fingers must drain it. “Pressing the fingertip onto a wet surface draws fluid from underneath the fingertip through the tubules, and then the entire finger is in contact with the surface,” the researchers described the effect.

In addition, wrinkles do not appear within the first five minutes after getting wet, so accidental contact with water passes without a trace. This reaction occurs only in the rain or during dew. In addition, fresh water causes wrinkles to appear faster than sea water - perhaps these are echoes of the conditions in which such a mechanism first arose in primates.

Even if this mechanism did not arise directly to strengthen the grip, it may persist for precisely this reason. A 2013 study by British neurologists found evidence that wrinkled fingers help people handle wet objects.

In the experiment, 20 people had to move 45 objects of different sizes - pebbles and sinkers - from one container to another. In some cases they were dry, with different subjects having both smooth and wrinkled skin. In other cases, objects were wet. It was found that wrinkled fingers made it easier to carry wet objects, but there was no difference for dry objects.

However, a similar study conducted in 2014 by German researchers found the opposite effect. 40 people carried 52 balls and cubes various sizes and scales between containers. The scientists found no difference in the ability to handle these objects, regardless of whether the subjects' fingers were wrinkled or not, or whether the objects were dry or wet.

Similarly, a group of Taiwanese researchers conducted experiments with the help of a volunteer. They measured the friction between a smooth surface and his smooth or wrinkled fingers. They also tested the subject's ability to bring the ends of the spring together. They found that in each of the tests, performance was worse when working with wrinkled fingers.

Of course, if the shrinking effect was the result of adaptation, it would have been tested under more natural conditions than in the laboratory.

Changini believes that this effect is useful for supporting the weight of the entire body, rather than for manipulating small objects. “If we are going to do tests where the effect matters, then we need to grab trees or heavy objects, not balls,” he says. “[When transferring balls between containers] you are not in danger of hydroplaning.” You want to associate this effect with movement, not agility.

It turns out that the ideal experiment, in his words, is to hire parkour enthusiasts to show their tricks with both smooth and wrinkled skin, alternately in dry and wet conditions. “We just need to somehow ensure their safety,” he adds.

Each of us knows from early childhood that the skin on our fingers begins to wrinkle from being in water for a long time. My parents even used to allow me to bathe in the bath until my fingers became covered with wrinkles. They said that since the fingers were already swollen from water, it was time to get out. But is this really so?

At first, scientists actually explained this phenomenon this way. In their opinion, due to the absorption of moisture, the area of ​​​​the upper layer of the skin increased, while the lower layers remained the same size. And supposedly because of this, our skin came out in waves.

But this version had several flaws. After all, if our skin really absorbed moisture, then the whole body would be covered with wrinkles, and not just the fingers. In addition, back in 1935, several doctors noticed that in patients with damaged nervous systems, the skin did not wrinkle from water. Therefore, an explanation for this phenomenon must be sought in the field of neurology.

Doctors have concluded that wrinkling of the skin on the fingers and toes is an involuntary reaction of the body to prolonged exposure to water. But what exactly causes this reflex?

Biological scientists believe that this reaction of the body was developed in the process of evolution. Thus, nature made sure that a person has better grip on various wet surfaces.

Wrinkled skin acts as a kind of tread on tires. Thanks to wrinkles, the density of adhesion to the surface increases. This makes it much easier for a person to catch fish in the water or move on wet grass.

And although we no longer walk barefoot for a long time, and we handle wet objects (for example, while washing dishes) with rubber gloves, this reflex is still useful. Next time you take a shower or bath, notice that a bar of wet soap is much easier to hold when your fingers become wrinkled.

This is how Mother Nature made sure that people could adapt to different conditions as best as possible. If this information came as a surprise to you, be sure to share it with your friends.

A photo of a guy's hand after a bath went viral on Reddit, showing wrinkles on all fingers except the middle one. The user said that it was in this finger that his nerve was damaged, and for many people it became a discovery why the fingers wrinkle after being for a long time in water.

Here's what Scientific American writes about this study.

Test participants tried to pick up wet or dry objects (for example, small glass marbles different sizes) fingers without wrinkles and fingers that the test subjects had previously kept for 30 minutes in warm water. Wet glass beads were better grasped by fingers with wrinkles, but wrinkles had no effect on the grasping of dry objects.

The scientists' hypothesis is that as soon as the body realizes that the fingers have been in the water for a long time, it sends a signal to the sympathetic nervous system, which responds including and for blood circulation. The blood vessels in the fingers are compressed, and due to wrinkles, peculiar channels are formed on them, like on car tires. Their function is the same: to prevent water from staying inside.

Scientists then wondered why, if it is so convenient, our fingers are not constantly wrinkled. But, they think, this would impair the quality of our sensations and our ability to catch something on the fly.

Upon learning of this, some people in the comments complained in fear that too many wrinkles were forming on their fingers. But they were reassured by writing that, most likely, this is due to the fact that everyone simply has different sensitivity of the nervous system. But it is not exactly.

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The user is not very worried about the fact that the “superpower” of fingers to wrinkle from water is absent on one of his fingers. On the contrary, he admits that it’s cool to always surprise friends with such a feature. In addition, this finger is a little colder than all the others. But at first, an unexpected inconvenience arose while driving the car.

When my finger was still in a bandage and therefore could not bend, I was very afraid that someone on the road would think that I was deliberately showing him the middle finger. And I just kept my hand on the steering wheel.

It’s good that Kai-ol is so positive about the wound on his finger, especially since he will soon regain full sensation. Another guy from the UK was not so lucky: he was born without an arm, but this does not stop him from joking about it on social networks and

Ever wondered why your skin starts to wrinkle if it's in water for a long time? The answer lies in the process of evolution, but it is not so easy to find.

About a century ago, surgeons discovered that if certain nerves in the fingers were cut out, the wrinkling reaction would disappear. Therefore, the fact that our fingers wrinkle is a sign of an intact nervous system. You should be scared; if this doesn’t happen, then something is wrong. Doctors began to determine how well a patient's sympathetic nervous system was functioning by whether the skin wrinkled when exposed to water. The scientific community has reached a consensus on this. But exactly how such a reaction evolved and what it represents is an adaptation to remains controversial.

Neuroscientist Mark Changizi of 2AI Labs believes this response is an adaptation to improve movement. To prove his point, he gives the example of protectors. In dry conditions, slick tires can have the best grip on the asphalt, which explains why racing cars tend to have slick tires. But when driving in the rain, protectors are much safer.

The scientist further suggested that the ability of our skin to wrinkle in certain conditions gives us the ability to move equally well in different weather conditions. Smooth fingers - for a dry surface, wrinkled - for a wet surface. Once the body understands that it is in water relatively long time- about five minutes, the “tires” are changed. It is extremely difficult to prove that any biological function is an adaptation, let alone how or why it evolved. Researchers in this field can often only look for such clues and analogies and speculate.

In 2011, Changizi and his colleagues found evidence that wrinkled fingers actually act as rain protectors, diverting water away from fingers and toes in wet conditions, allowing primates—humans and macaques, to be specific—to have a tighter grip. It can be said that the wrinkles that appear act as a drainage system in which several small streams combine into larger channels and ultimately drain water into the central river. Only here the reverse process occurs.

To see if the fingers had the same pattern as river drainage systems, Changizi and his team analyzed photographs of 28 human fingers. They found that the wrinkled fingers were patterned like a system of canals. But if in rivers these channels exist to pool water, then the patterns on the fingers are designed in such a way as to drive away water from the surface of the fingers, feet and palms. If you press on a hard surface with a wrinkled finger taken out of the water, water will come out of these channels under the force of pressure.

It is equally important that wrinkles do not appear until the skin has been in water for about five minutes, that is, accidental contact with water is not enough to lead to the formation of wrinkles, this mechanism can only work with prolonged contact with water. In addition, the reaction occurs much faster in fresh water than in sea water.

A 2013 study by British neuroscientists found that people's wrinkled fingers help them better manipulate wet objects. During the experiment, 20 people had to move 45 objects of various sizes from one container to another. In one case, the objects were dry while the participants' fingers were smooth or wrinkled after being in water. In other cases, objects were submerged in water. It turned out that wrinkled fingers allowed participants to move wet objects more quickly, but in the case of dry objects, no difference was noticed.

The hypothesis sounds nice, but a similar study conducted by German scientists in 2014 found the opposite. In this experiment, 40 people volunteered to transfer 52 glass beads and cubes of varying sizes and weights from one container to another. The researchers found no significant differences in participants' ability to handle objects, regardless of whether their fingers were smooth or wrinkled or whether the objects were dry or wet.

A group of Taiwanese researchers conducted their experiment, the participants of which were men aged 24 years. Scientists assessed the friction of skin in contact with a smooth surface - how much force needed to be applied to make the skin (wrinkled or smooth) slide along the block. The researchers also assessed the ability to compress the spring under different skin conditions. They found that when the skin was wet and wrinkled, the results were worse.

Of course, if the ability of the skin to wrinkle is a type of adaptation, then this mechanism did not develop for some laboratory conditions in which experiments are carried out. Mark Changizi believes that this mechanism helps a person support his own weight in a humid environment, and does not serve to move small items. He believes that to find the answer to why skin wrinkles in water, the experiments themselves need to be modified so that participants hold tree trunks or even heavier, larger objects, rather than dragging small objects from one container to another. According to Chingizi, the key to the puzzle lies in assessing the effect of wrinkled skin on movement, not dexterity. The ideal experiment, according to Changizi, could be staged with the participation of parkour athletes - urban acrobats who will demonstrate their tricks with different skin conditions and in different weather conditions.