Why do your fingers get wrinkly in the bath?

Why do you your fingers go wrinkly when you’re in the bath?

Asked by Sam Young (Aged 5, asked by his mother via Facebook)

Hi, Sam! Great question!

The reason our fingers get all wrinkly when wet is actually caused by the washing away of an oily layer sitting on the top of our skin. According to Daven Hiskey, we usually don’t notice this oily layer (well, except when you don’t wash your hair for a few days and you get that greasy feeling). The oily layer is called “sebum” and has a couple important tasks. One, it helps keep your skin and hair healthy by maintaining the proper hydration level. And two, just as sebum keeps your skin and hair hydrated, it also helps them steer clear of too much moisture. Thus, when you’re in the bath or swimming, you wash off this protective layer of oil and your fingers get shrivelled!

A question that still is a mystery to the science community is why do only our fingers and toes get wrinkly? Why not our entire body? Hiskey points out that our fingers and toes contain a thicker layer of dead and living keratin, a protein on the skin’s outer layer, the epidermis, than the rest of our body. When we’re in water, the oily sebum gets washed away causing the dead keratin cells absorb the liquid. Since there’s thicker keratin on our fingers and toes, the wrinkling is much more apparent.

So what’s the purpose of wrinkling? Neuroscientist Mark Changizi recently suggested one of the most interesting reasons. He suggests that wrinkly fingers are actually more ‘grippy’ than our dry fingers. Think about the tyres on your car—if they’re in good shape, they should have treading on them to help your vehicle grip the road and maneuver in rainy weather. This is the same logic behind the purpose of our wrinkly fingers. The wrinkles are another amazing tool we can thank evolution for!

Answered by Kim Lacey (Mind Guru)

Further reading:



Article by Kim Lacey

October 30, 2012

With a PhD from Detroit’s Wayne State University, Kim Lacey from Detroit, USA, knows a thing or two about memory studies, digital media and digital humanities. She also has a serious addiction to combo plates at restaurants. You can read about Kim at kimberlylacey.com or follow her on Twitter at @kimlacey.

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