Why do fingers wrinkle when soaked in water?

Fingers are parts of the body that people pay great attention to, because the sensory nerves in the fingers are very developed and can sense most of the objects they touch. In addition, the skin of the fingers is very distinctive and relatively thick, which can effectively block bacteria. However, the thick skin on the fingers will cause wrinkles if they are soaked in water for too long. Let’s take a look at why the fingers wrinkle when they are soaked in water.

The formation of bubbles when fingers are soaked in water is a result of human evolution, which helps humans better grasp slippery objects.

No one can escape the fate of wrinkled fingers after soaking in water for a long time. It has long been believed that wrinkling is caused by osmosis, which causes water to enter the epidermis of the fingers. In 2011, American scientists overturned the above view and proposed that this process is actually controlled by the nervous system.

When fingers are soaked in water for a long time, the nerves will cause the diameter of the blood vessels at the fingertips to decrease. At this time, the surface area of ​​the skin remains unchanged, so grooves appear on the fingers. Scientists can't help but wonder if this is the same principle as in car tires, where grooves improve the grip of human fingers on wet surfaces.

Other scientists speculate that wrinkling of fingers when exposed to water is the result of natural selection. The grooves increase the adhesion of fingers, improving humans' ability to catch fish with their bare hands, thereby increasing the possibility of human survival in nature.

1. Skin causes

When soaking in water for a long time, a large amount of water will flow through the cell membrane into the space between the epidermis and the dermis. The epidermis is mainly composed of the stratum corneum, which will swell after absorbing water. The dermis under the stratum corneum is connective tissue and will not swell due to absorbing a large amount of water. This will cause the volume between the two layers of skin tissue to change, thereby causing wrinkles.

The moisture between the stratum corneum and the dermis will also create gaps between the two layers of skin tissue, causing separation between the layers, which also promotes the occurrence of wrinkles.

2. Cellular causes

Water occupies an absolute dominant position inside the human body, and the liquid concentration in the body is relatively high. Therefore, after soaking in fresh water for a long time, the water will be absorbed by the epidermal cells of the skin, causing the cells to swell and deform. When swimming in seawater with a higher concentration, wrinkles appear on the fingers due to the loss of water from the epidermal cells, causing the cells to shrink and deform.