Why do your fingers or hands wrinkle in water?
What are wrinkled hands? Have you ever noticed your fingers and toes wrinkling or pruning after swimming in the pool, taking a long scuba dive, or even just washing the dishes?
This is one of the body's weird biological response to prolonged exposure in the water, but do you know why?
Well, there is no definite answer to why our skin wrinkles up in water, but there are theories! This week, we talk about "how and why" water temporarily makes your fingers and toes wrinkle in water.
Wrinkled Fingers and Theories
Theories are theories
One theory why our hands and feet wrinkle when immersed in water is that blood vessel constriction (vasoconstriction) acts to oxygenate and protect vital organs in a manner similar to the Mammalian Diving Reflex. Blood is first shunted away from the extremeties (hands and feet), which are the least vital areas of the body.
The Mammalian Diving Reflex The Mammalian Diving Reflex (aka Diving Response, Mammalian Dive Response, Mammalian Dive Reflex) is the response of many mammals (including humans) to the cooling of the face (for example, when it is immersed in water) while holding one's breath. The body automatically takes actions to immediately adapt to the decreasing levels of available oxygen.
One of those actions is to contract the muscles in blood vessel walls, making the blood vessels more narrow (vasoconstriction). This reduces blood flow to less vital areas of the body, thus prioritizing oxygenation of the brain, heart, and other vital organs. Blood is also sent to the body's compressible spaces to protect these vital organs (especially the lungs) from collapsing under increasing pressures at deeper depths. is an adaptation to oxygen deprivation. However, the body also rapidly loses heat when immersed in water. Perhaps wet hands and feet signal to the body that it needs to protect its vital organs from heat loss. Wrinkling is a consequence of digital vasoconstriction (explained below).
Some theorize that skin wrinkling evolved to impart better traction (like the tread on a tire) and grip under wet conditions. However, at least two studies have debunked this as a myth while at least two studies have confirmed it. The fact that even warm water causes vasoconstriction, instead of the vasodilation we should expect, supports the idea that there must be an evolutionary benefit.
Immersion-related wrinkling is known to occur in at least one other species, macaques; additional research is needed to find others. Additional research is also needed to explain why our hands and feet are not permanently as wrinkled; some hypothesize that wrinkling would decrease fingertip sensitivity or that the grooves would increase susceptibility to damage from touched objects.
Why does skin wrinkle in water?
People used to think that it is caused by osmosis, the movement of liquid molecules through cell walls. They believed that body soaks up water, thus creating the bumpy, wrinkly effect on our hands and feet. But wouldn't the rest of our body be wrinkly too? Therefore, this theory is considered false.
It wasn't until 1935 when Dr. T. Lewis and Dr. GW Pickering noticed that patients with nerve damage on their feet and hands don't experience the wrinkling in water.
This means that the wrinkling is an involuntary response of our sympathetic nervous system, the part of the nervous system that controls our "fight or flight" response.
Wrinkling due to prolonged exposure in water only occurs on the glabrous skin.a thicker skin where hair won't grow (like the skin on your palms, fingers, toes, and soles). When our sympathetic nervous system is stimulated, the blood vessels in our hands and feet start to constrict, making the blood vessels more narrow; this is known as vasoconstriction. Because of the reduced blood flow, the blood vessels in our palms and soles shrink, resulting in white wrinkly fingers.
Wrinkled fingers and toes resulted from evolution
The most recent theory proposed is that wrinkled fingers are an evolutionary adaptation. Some studies have shown that the wrinkling of our fingers and toes allow for better grips on wet objects and tractions on slippery and wet surfaces (like how treads on a tire work). This is an evolutionary advantage to our ancestors and us.
It may have helped our ancestors get a better grip when gathering food from beaches and streams. It may also have made it safer to travel barefoot on wet rocks and moss or escape predator under the rain. Now, most of us may not be gathering food like how our ancestors did, but the wrinkling of our fingers and toes is still an advantage for us.
When washing dishes, it can help us hold the wet plates better, or when walking by the pool barefoot, it keeps us from falling on the slippery floor (but hey, this doesn't mean you can run or not be careful when walking with wet feet).
Why don't my arms and legs wrinkle?
The reason why water immersion does not cause arms and legs to wrinkle may be that the degree of vasoconstriction is less in those areas. One study shows that the most vasoconstriction occurs in the fingers and toes, which is also where wrinkling is the most noticeable.
Furthermore, take a moment now to look at the bottoms of your hands and feet. Even if they are completely dry, you should still see fingerprints, palm lines, and quite a few deep wrinkles. Now look at your forearm, and observe how smooth it is in comparison.
Simply put, the thicker skin layers on our hands and feet are more prone to wrinkling.
Why do your fingers or hands wrinkle in water Researches and References
If you want to know more about wrinkled fingers, take a look at some of our references below.
Images we use are from Wikimedia commons and Free online photos.
- Why Do Fingers Prune in Water?
- Stimulated skin wrinkling as an indicator of limb sympathetic function
- Why Does Water Make You Wrinkle?
- Why Do Fingers Wrinkle in Water?
- Why are my fingers pruney or wrinkled?
- Here’s Why Your Hands Wrinkle in Water
- Wikipedia Wrinkle water immersion
- Fingers Wrinkles
- Why do our fingers get pruney
- Water Immersion Wrinkling
- Skin Wrinkles in water
- Mammalian dive response
- Fingers Prune underwater
- Why do our fingers and toes wrinkle during a bath
Speaking of wrinkled hands, now I want to eat prunes...
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Thanks for reading, and if you wish, see you next week!
The Research and Media Team at Scotty's.