Why do fingers wrinkle in water, but not for everyone? It turns out this phenomenon is actually beneficial.

In today's world, many of us enjoy taking long hot baths, but if we stay in for too long, we may notice that the skin on our fingers becomes wrinkled. Some suggest this happens because we are simply absorbing moisture, but in reality, human skin is waterproof. Moreover, not everyone experiences wrinkling while in the bath. So what is actually happening? Scientists have provided an answer, as reported by IFLScience.

Researchers studying the thin layer of skin found that it exhibits an unusual arrangement of lipids, where two hydrophobic tails point in opposite directions. Typically, the hydrophilic head of a lipid points in one direction, while its two hydrophobic tails point in the other; this alternating arrangement allows lipids to pack more tightly, making the skin even more impermeable to water.

This works both ways, meaning water neither penetrates nor escapes from beneath the skin. In simple terms, this implies that the wrinkling of our fingers cannot solely depend on the skin absorbing moisture.

As early as 1935, doctors first noticed that patients with severed median nerves did not experience wrinkling in their fingers when they spent extended periods in water. Scientists also discovered that the degree of wrinkling depended on the specific location of the median nerve damage. For instance, some fingers of patients might continue to wrinkle. Following this experiment, doctors suggested using finger wrinkling as a test for nerve damage.

It is known that the median nerve is involved in functions that a person cannot consciously control, such as sweating, and it is also part of the human sympathetic nervous system. It is noteworthy that the sympathetic nervous system is responsible for preparing various systems in our body for action, performing functions such as:

• increasing heart rate;
• respiration rate;
• blood pressure.

At the same time, the parasympathetic system does the opposite, activating changes that allow a person to calm down again. This raises the question: if the sympathetic system signals us through wrinkled fingers, what is it preparing us for?

Scientists are uncertain about the answer, but one theory suggests that wrinkled fingers have deep roots in our evolutionary history. It is believed that wrinkled fingers are an adaptation that allowed our ancestors to grasp objects with wet hands. In simple terms, these grooves on the fingers act like "tire treads," providing better grip.

Evidence supporting this theory lies in the fact that the wrinkles on the fingers function as drainage channels, repelling water in their path. As a result, we achieve more skin contact with the object.