'Prune fingers' may be evolutionary help

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NEWCASTLE, England, Jan. 9 (UPI) -- The mystery of why fingers get wrinkled when we swim or bathe for long periods is about making wet objects easier to pick up and handle, British scientists say.

Researchers from Newcastle University, who conducted experiments confirming the improved "traction" of wrinkled fingers, suggest our ancestors may have evolved the creases as they moved and foraged for food in wet conditions.

In the experiments, volunteers were asked to pick up marbles immersed in a bucket of water and deposit them in a second container.

Subjects with wrinkled fingers from extended immersion in water completed the task faster than their smooth-skinned counterparts, the researchers said.

Scientists had long assumed the wrinkles were just a result of skin swelling in water, but studies have show the wrinkling is a response controlled by the body's sympathetic nervous system.

"If wrinkled fingers were just the result of the skin swelling as it took up water, it could still have a function but it wouldn't need to," Newcastle researcher Tom Smulders told BBC News.

"Whereas, if the nervous system is actively controlling this behavior under some circumstances and not others, it seems less of a leap to assume there must be a function for it, and that evolution has selected it. And evolution wouldn't have selected it unless it conferred some sort of advantage."

The advantage of better-gripping fingers and feet would help our early ancestors as they foraged for food along lakeshores and by rivers, the researchers said.

"If it's in many, many primates then my guess is that the original function might have been locomotion through wet vegetation or wet trees," Smulders said.

"Whereas, if it's just in humans that we see this then we might consider something much more specific, such as foraging in and along rivers and the like."