Soaking hands causes visible wrinkling, and they invariably boast the same pattern of creases.

In a fascinating discovery that could potentially revolutionise biometric identification, a team of researchers has found that the patterns of wrinkling on fingertips when submerged in water remain consistent and repeatable over time.

The study, published in the May issue of the Journal of the Mechanical Behaviour of Biomedical Materials, was initiated by a simple, innocent question posed by a reader. German researcher, [Name], and a graduate student set out to investigate the consistency of fingertip wrinkle patterns.

Through a series of experiments, they discovered that the wrinkling of fingers and toes when underwater is not due to the skin swelling as it absorbs water, but rather due to blood-vessel constriction. When excess water enters the skin during a prolonged soak, the change in the amount of salt in the tissue triggers a signal to the brain, which instructs the blood vessels to narrow.

The researchers found that the patterns of wrinkling are determined by the paths of blood vessels below the skin's surface. Images from the same finger on different days showed pairs of wrinkles with similar locations and shapes, and mathematical analysis confirmed that the wrinkles were nearly identical.

Interestingly, the ridge patterns of fingerprints remain stable and do not change with age during the appearance of water-induced skin wrinkles on the fingers. This could potentially mean that fingertip wrinkle patterns might also remain constant throughout a person's lifetime, similar to fingerprint patterns.

However, the experiment did not determine whether blood-vessel patterns shift with age, leaving this question unanswered. The study involved three participants who submerged their right hands in water at 40 degrees Celsius for 30 minutes, with repeated sessions at least 24 hours apart. Photographs were taken of each participant's pruney finger pads after each session.

The wrinkling of fingers and toes is an evolutionary tool that boosts grip strength underwater by creating texture. If fingertip wrinkle patterns do remain constant, they could potentially be used for biometric or forensic identification in the future. This discovery opens up exciting possibilities for future research in this area.

Soaking hands causes visible wrinkling, and they invariably boast the same pattern of creases.