Wrinkled fingers fresh out of the shower may serve an adaptive purpose beyond bemusing their human owners. One evolutionary neurobiologist has a hunch that pruney human fingers and toes could provide a natural blueprint for new tread designs on shoes and tires, so that runners or drivers can move about safely in slippery conditions.
The idea came to Mark Changizi, director of human cognition at 2AI Labs, when he read a paper from the 1930s which casually mentioned how nerve damage in fingertips prevents them from wrinkling. That suggested wrinkling has an adaptive purpose, if the phenomenon falls under the control of the body's nervous system — but for what? "They're rain treads," said Romann Weber, one of Changizi's graduate students.
Early hints came from comparing wrinkled fingertips with the predicted patterns for water drainage channels. Such channels — similar to the drainage networks found on mountains — might someday also inspire the grooves patterned into human footwear. But the application could prove trickier for tire treads because of how tires roll, Changizi said.
"For feet, it's more straightforward," Changizi told InnovationNewsDaily." It may not look like what fingertips look like, but more like river drainage. Instead of a convex mountain on your feet, you'll have valleys."
More suggestive evidence came from one student's undergraduate thesis that showed how people with pre-wrinkled fingers did better while moving heavy objects in a wet environment. Studies by other researchers might help quantify how much better wrinkled fingers are compared to unwrinkled fingers in wet conditions.
So far, Changizi has only found data about humans and one macaque species having wrinkled fingers — the primate labs he contacted had never thought to check on such features. He suspects that animals with claws don't need such finger or toe wrinkling because claws are "more dual purpose" in both wet and dry weather.
"Where I sit as a theorist is identifying a new theory and hopefully making a strong case for it," Changizi said. "If someone happens to show interest from a tire or shoe tread perspective, they could come to us."
The research was published on June 23 in the online edition of the journal Brain, Behavior and Evolution.