Fingers get wrinkly in water because it is an active process controlled by the autonomic nervous system. When immersed in water, blood vessels in the fingers constrict, causing the skin to shrink and form wrinkles. This wrinkling improves grip on wet objects, similar to how tire treads work, and is believed to be an evolutionary adaptation for better handling of wet items or providing traction in wet environments.
Mechanism
The wrinkling is not just water absorption and swelling but results from nerve signals causing blood vessels below the skin to constrict. This reduces the volume beneath the skin surface, causing the skin to wrinkle.
Evolutionary Purpose
Wrinkly fingers help improve grip on wet or submerged objects by channeling water away, thus enhancing handling and traction in wet conditions. This likely helped ancient humans gather food or move safely in wet environments.
Additional Notes
- The wrinkling usually starts after a few minutes in warm water and peaks around 30 minutes.
- People with nerve damage in their fingers may not experience this wrinkling, confirming the nervous system's role in this process.
In summary, finger wrinkling in water is a beneficial, evolutionary nervous system response to enhance grip on wet surfaces.
