Are Wrinkles Natural?
Yes, and they may be useful too.
This article is not about the wrinkles on your face. Those wrinkles are the proof you have obtained the wisdom of age and not the vanity of BOTOX.
This article is about your hands and feet. Why do your fingers and toes go from plump to wrinkled when you soak in water?
When I cook with raisins they go from wrinkled to smooth. When I soak dried beans they swell. This is due to osmosis. Osmosis is the movement of a liquid across a semipermeable membrane such as the skin of a raisin.
However, when you soak in water, you do not absorb the liquid. You would truly become “water-logged” if that were the case. Is the opposite of absorption happening? Are you dehydrating when you soak in water?
How Do Your Fingers Wrinkle in Water?
Osmosis is the movement of a liquid across a semipermeable membrane. For many years people thought it was osmosis that caused your fingers and toes to turn into prune digits when you have a big soak. But that was not the case.
It’s All in Your Head
In the 1930s, researchers noticed patients with injuries that severed the median nerve, in the arm, had fingers that would not wrinkle. The median nerve is part of the sympathetic nervous system. This system keeps the body in homeostasis, that is, your systems in balance, such as blood sugar, temperature, and gas exchange.
The median nerve controls your finger wrinkling in response to a soak in the tub.
More recent studies have found that blood vessels in the fingers and toes constrict in response to water.
Why?
What is the evolutionary advantage of wrinkled toes and fingers?
Your nervous system causes your fingers and toes to wrinkle in response to water. Why? What is the advantage?
Do the wrinkles increase your grip strength? This was a question asked by Nick Davis, a neuroscientist at the Manchester Metropolitan University. He found that it took more grip strength to hold on to an object with wet hands than dry hands. However, if the hands were soaked, the amount of strength required was less than just wet hands. So wrinkled fingers reduced the strength required to hold objects in wet environments.
Therefore, running at the poolside is less dangerous if your feet have turned into prunes, otherwise, you are likely to slip.
The wrinkle strength advantage suggests an evolutionary benefit for one of our hominid predecessors. Was there an advantage for the ancient hominids grabbing food in riverbeds or tidepools?
The only other animal observed with wrinkled appendages are the Snow Monkeys of Japan.
As we age we get wrinkles on our fingers. Is there an evolutionary advantage? No. But it does help us hold on to the ones we love a little longer.
