New research reveals the surprising reason behind finger wrinkles when wet, uncovering a hidden pattern that could revolutionize biometric identification.
The Science Behind Wet Finger Wrinkles
Finger wrinkle patterns induced by a long soak always follow the same paths. Researchers suggest that these patterns are determined by the blood vessels below the skin’s surface.
Blood vessels are tubular structures that transport blood throughout the body.
They consist of arteries, which carry oxygenated blood away from the heart, veins, which return deoxygenated blood to the heart, and capillaries, where exchange of nutrients and waste products occurs.
The circulatory system relies on blood vessels to supply oxygen and nutrients to tissues and organs, while also removing waste products.
A network of over 60,000 miles of blood vessels exists in the human body, with some capillaries being as thin as 1/5 the width of a human hair.
The idea that fingers and toes wrinkle when wet is often attributed to the swelling of the skin due to water absorption. However, research has shown that this is not the primary cause. Instead, it is the constriction of blood vessels that leads to the puckering of the skin. When the skin absorbs water, it dilutes the amount of salt in the tissue, which signals the brain via nerves. In response, the brain instructs stationary blood vessels to narrow, pulling in the overlying skin.
This phenomenon serves an evolutionary purpose by creating texture and boosting grip strength underwater. ‘The idea that fingers and toes wrinkle when wet is often attributed to the swelling of the skin due to water absorption.’ However, research has shown that this is not the primary cause. Instead, it is the constriction of blood vessels that leads to the puckering of the skin.
Guy German, a biomedical engineer at Binghamton University, investigated why water makes skin shrivel. However, he was stumped when asked if the wrinkles occur every time and follow the same pattern.
To answer this question, German and his graduate student conducted an experiment where three people submerged their right hands in water at 40° Celsius for 30 minutes and then took photos of each pruney finger pad. The participants repeated this process at least 24 hours later. By overlaying images from both days, the researchers found that the corresponding wrinkles matched almost perfectly.
The repeatability of wrinkling topography patterns suggests that the blood vessel arrangements in the digits remain consistent over time. This has significant implications for biometric or forensic identification, where finger wrinkle patterns could potentially be used to identify individuals. The origin of this story is a testament to the power of curiosity and research, leading to a deeper understanding of an often-overlooked phenomenon.
- sciencenews.org | Wet fingers always wrinkle in the same way
