The answer to the question "why do fingers wrinkle if soaked in water for a long time?" has been found.

Volunteers soaked their hands in water for 30 minutes. They repeated the process 24 hours later, and the imaging results showed the same wrinkles as before.

The lines (in black) trace the wrinkles in the two images very similarly (Photo: Laytin & German).

As water seeps through sweat capillaries into the skin, it reduces the salt concentration in the outer layer of the skin on the fingertips. Nerves transmit signals to alert the brain to this change in skin condition, which then triggers automatic vasoconstriction.

As these tiny blood vessels constrict, they pull the surface of the skin down, causing the normally smooth skin on the fingers and toes to contract into a rough, wrinkled texture.

Changes in one of the volunteer's fingertips during the experiment (Photo: Laytin & German).

"The blood vessels don't change position much, but compared to other blood vessels, they're pretty static. That suggests that wrinkles will form in the same way, and we've shown that," said Professor Guy German, a biomedical expert at Binghamton University in the US, lead author of the study.

The wrinkling of skin when immersed in water is not just a random side effect. These changes provide a measurable advantage in wet conditions: the skin’s temporary grooves and ridges provide better grip, making it easier for us to walk or grasp wet objects.

If these wrinkles help us grip better, why isn’t the skin on our hands always wrinkled? While researchers aren’t sure why, they think the temporary wrinkled texture may reduce the sensitivity of our fingers or make them more vulnerable to injury.

This phenomenon is precisely controlled by the body with the participation of the nervous system, because monitoring shows that people with damaged nerves in the middle of the fingers do not have wrinkled fingertips after soaking in water for a long time.

The discovery could aid forensics, for example understanding the deformation of finger skin could help identify bodies after prolonged exposure to water or after natural disasters.

Thus, in addition to fingerprints, which have long been considered a sign of individual identification, scientists can now have more basis thanks to the unique finger skin wrinkle pattern of each person.

Source: https://dantri.com.vn/khoa-hoc/da-tim-ra-loi-giai-cho-cau-hoi-vi-sao-ngon-tay-nhan-neu-ngam-nuoc-lau-20250516002049967.htm