Every time an object submerges, fingers exhibit wrinkles, consistent in their pattern

In a fascinating discovery made around two decades ago, researchers uncovered the role of blood vessel constriction in the wrinkling of fingers and toes underwater. This revelation, published in the Journal of the Mechanical Behavior of Biomedical Materials, sheds light on an evolutionary tool that has long puzzled scientists.

Guy German, a biomedical engineer at Binghamton University in New York, has been delving into the consistency of finger wrinkling patterns over time. His research reveals that these patterns, while following the paths of blood vessels below the skin's surface, remain virtually unchanged and unique throughout a person's lifetime.

The process begins when a prolonged soak leads to water entering the skin, causing a decrease in salt concentration in the tissue. This change in salt concentration sends a signal to the brain via nerves, instructing stationary blood vessels to narrow. The constriction of these blood vessels under the skin is responsible for the wrinkling effect, not the swelling of the skin due to water absorption.

The shrinking of blood vessels pulls in the anchored overlying skin of fingers and toes, creating the texture that boosts grip strength underwater. This discovery, according to German, opens up a door to essentially unknown science, with potential implications for biometric or forensic identification.

German and a graduate student tested finger wrinkling patterns by having three participants submerge their hands in water at 40 degrees Celsius (104 degrees Fahrenheit) for 30 minutes, repeating the process at least 24 hours later. Images of the same finger one both days matched, revealing pairs of wrinkles that shared similar locations and shapes. Mathematical analysis confirmed the wrinkles were nearly identical, suggesting consistency over short periods.

However, it remains unclear whether blood-vessel patterns shift with age, but fingerprints stay the same over a lifetime. If finger wrinkle patterns also remain consistent over long periods, they might prove to be a valuable tool in the field of biometrics and forensics.

This intriguing study originated from a simple, innocent question posed by a reader. The next time you take a dip in the pool and notice your fingers and toes wrinkling in specific, repeatable patterns, remember the fascinating science behind this evolutionary tool.