Finger wrinkles from water could help solve crimes

Have you ever noticed how your fingers become wrinkled when soaked in water? The longer you stay submerged, the more pronounced those wrinkles become.

But do those wrinkles form in the same pattern every time? That intriguing question recently caught the attention of scientists at Binghamton University, State University of New York (SUNY).

A couple of years ago, Professor Guy German published a breakthrough study on why skin wrinkles in water. The common explanation was that water caused the skin to swell, which leads to wrinkling. However, German’s research revealed a more complex story beneath the surface.

How finger wrinkles form

Before Professor German’s study, the prevailing belief was that water absorption alone caused skin to wrinkle.

However, the team at the Biological Soft Matter Mechanics Laboratory found that blood vessels beneath the skin actually contract after prolonged exposure to water. This contraction is what creates those familiar loops and ridges on your fingers.

Professor German initially discussed his findings in a 2023 article for The Conversation’s Curious Kids feature. It wasn’t a peer-reviewed journal, but a student’s question that pushed German to dig deeper.

“A student asked, ‘Yeah, but do the wrinkles always form in the same way?’ And I thought: I haven’t the foggiest clue!” said Professor German.

Consistency in water-induced wrinkles

Motivated by the student’s question, the team set out to determine whether the same wrinkle patterns appear after each water immersion.

The study was led by Professor German and Rachel Laytin, a graduate student who was pursuing her Master’s degree. They designed a simple but effective experiment to investigate the question.

Subjects placed their fingers in water for 30 minutes, then had their fingers photographed. The procedure was repeated under identical conditions at least 24 hours later.

By comparing the before-and-after images, the researchers could assess whether the wrinkle patterns remained consistent.

Do wrinkles always form the same way?

The results, published in the Journal of the Mechanical Behavior of Biomedical Materials, confirmed that the wrinkle patterns remained unchanged across multiple immersions.

“Blood vessels don’t change their position much – they move around a bit, but in relation to other blood vessels, they’re pretty static,” explained Professor German. “That means the wrinkles should form in the same manner, and we proved that they do.”

The experiment revealed that, despite the variability in other aspects of skin physiology, the underlying blood vessel network remains relatively static. This stability ensures that the topography of water-induced wrinkles is consistent from one immersion to the next.

Nerve damage prevents water wrinkles

While investigating wrinkle patterns, the researchers stumbled upon an unexpected finding.

“We’ve heard that wrinkles don’t form in people who have median nerve damage in their fingers,” said Professor German. “One of my students told us, ‘I’ve got median nerve damage in my fingers.’ So we tested him – no wrinkles!”

This observation could open doors to further research on how nerve damage affects skin behavior under water. It also suggests a potential diagnostic tool for identifying nerve damage based on the presence or absence of water-induced wrinkles.

A family connection to forensics

While the study’s origins stem from a student’s simple question, its implications could extend far beyond the lab.

German’s father, a retired police officer in the U.K., dealt with the challenges of identifying bodies recovered from water. Understanding how wrinkle patterns form and remain consistent could aid in forensic investigations, including fingerprinting at crime scenes.

“Biometrics and fingerprints are built into my brain,” said Professor German. “I always think about this sort of stuff, because it’s fascinating.”

Future research on water wrinkles

The study has not only answered one intriguing question but also opened the door to many more. German is eager to explore further questions about how skin responds to prolonged water exposure.

He believes the Curious Kids feature and the thought-provoking question from a young student were instrumental in inspiring this research.

“I feel like a kid in a candy store, because there’s so much science here that I don’t know. We thank the people at The Conversation and the wonderful question they asked us, because it does create cool new science,” he said.

Broader implications of the research

The study has added a new layer of understanding on how human skin behaves under water. The findings could be applied not only in forensic science but also in medical research, particularly in studying skin conditions and nerve damage.

For now, the simple question that sparked the study has been answered: Yes, water wrinkles form in the same pattern every time.

Yet, the implications of this finding are far from simple. By exploring the relationship between blood vessels and skin topography, German and his team have laid the groundwork for further studies that could transform our understanding of skin physiology and its response to external stimuli.

In the end, what began as a child’s question became a compelling scientific inquiry that has lead to new discoveries and to more questions that are waiting to be answered. And for German, that’s the best part of being a scientist – the constant pursuit of the unknown.

The study is published in the Journal of the Mechanical Behavior of Biomedical Materials.

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