• picture
  • picture
PRI's Environmental News Magazine

Science Note: Why We Get Bathtub Wrinkles

Air Date: Week of February 8, 2013

stream/download this segment as an MP3 file

A wrinkled finger after a warm bath. Researchers found that wrinkles improve grip in wet conditions and they argue the puckered skin probably provided an evolutionary advantage to early humans. (Photo: Wikipedia)

Scientists think they have an evolutionary answer to why we get wrinkly fingers and toes after a soak in the tub. Living on Earth’s Annie Sneed reports.

Transcript

SNEED: Hang out in the bathtub too long and your fingers and toes shrivel up like raisins. It’s not obvious why soaking in water results in wrinkles. But now, scientists think they have an evolutionary answer to this apparently useless trait. Back in the 1930s, researchers noticed the fingertips of people with nerve damage in their hands weren't wrinkled after being soaked. They concluded that the nervous system must cause this wrinkling, much as it does other involuntary responses such as breathing or sweating.

Yet for years researchers had no scientific explanation for why this would happen. Now a group of evolutionary biologists at Newcastle University in the UK think they have an explanation. They conducted a study where participants picked up wet and dry objects, such as marbles, either with dry hands, or after steeping their hands in water. The people with wet, wrinkly fingers picked up wet marbles more handily than those with dry fingers. But it made no difference whether hands were wet or dry when picking up dry marbles.

The researchers concluded that wrinkles improved grip in wet conditions. They compared the wrinkles on fingers and toes to treads on a car tire, and argued that they probably provided an evolutionary advantage to early humans. Wrinkled fingertips would have helped them forage and grip in wet vegetation or water. The same goes for toes - wrinkles would have given them better footing on wet ground. Even though we no longer go wading into marshes to gather our food, the adaptation remains. So next time you're soaking in the bathtub, keep one hand wrinkle-free, and give the marbles a try. For Living on Earth, I'm Annie Sneed.

 

Links

Newcastle University’s Tom Smulders explains the evolutionary reason for bathtub wrinkles on the Guardian

 

Living on Earth wants to hear from you!

P.O. Box 990007
Prudential Station
Boston, MA, USA 02199
Telephone: 1-617-587-2660
E-mail: comments@loe.org

Donate to Living on Earth!
Living on Earth is an independent media program and relies entirely on contributions from listeners and institutions supporting public service. Please donate now to preserve an independent environmental voice.

Newsletter
Living on Earth offers a weekly delivery of the show's rundown to your mailbox. Sign up for our newsletter today!

Experimental
We have a new community section. Tell us what you think!

Major funding for Living on Earth is provided by the National Science Foundation.

Committed to healthy food, healthy people, a healthy planet, and healthy business.

Innovating to make the world a better, more sustainable place to live.

Kendeda Fund, furthering the values that contribute to a healthy planet.

The Grantham Foundation for the Protection of the Environment: Committed to protecting and improving the health of the global environment.

Contribute to Living on Earth and receive, as our gift to you, an autographed copy of one of Mark Seth Lender's extraordinary hummingbird photographs. Follow the link to see Mark's current collection of photographs.