Simply Science: Wrinkly Wet Fingers come from Evolution

SAINT PAUL, Minn. - We all know that spending too much time in the pool or bathtub leads to pruney fingers. It's a biological process controlled by our autonomic nervous system, which meansit happens automatically without us thinking about it.

"It's the constriction of the blood vessels in the finger tips, which makes the exterior skin wrinkle," explains Mark Borello, Professor of Ecology, Evolution and Behavior at the University of Minnesota.

A United Kingdom study published in the scientific journal, Biology Letters, takes it a step further by asking, "If this is sort of a passive trend, then maybe there's a function," as Borello puts it.

The theory is that the ridges that form on our finger tips may help us grip and move slippery objects more efficiently.

I put the theory to the test in a similar way. While the UK study used marbles, I used baby carrots in a sink of water. First with non-pruney fingers I moved them through a hole in a piece of cardboard and into a cup. I then soaked my fingers in warm water until they were wrinkly and performed the same task over again.

My results? A 9% increase in efficiency for moving the carrots with wrinkly fingers.

But the UK study doesn't offer any cold hard facts.

"What we have now is a hypothesis, we some sort of minimal empirical evidence for sort of a plausible story, but I don't think we have anywhere near what most evolutionary biologists would think is a strong evolutionary account," said Borello.

In order to strengthen that account, future studies may ask, Is this a unique trait to humans or do we share it with our closest relatives? Or are there variations of the trait between costal and desert populations?

Borello does give some credit to the UK study.

"It's interesting, and if it gets people to think about evolution and think about science, then great."


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