Finger wrinkles

You know that dramatically wrinkling that occurs when your fingers and and toes get wet?

The classic explanation has been that such wrinkling is caused by osmosis.  But if you think about it, why does it occur only on the palmar and plantar skin surfaces?  My face doesn’t wrinkle when it’s wet.  Well, OK, my face is always a bit wrinkled—wet or not.

Some scientists are now thinking that this is not an osmotic effect but, instead, a nervous response to wetness.  According to this latest theory, such a response helps us avoid slipping and injuring ourselves in wet conditions.  It would also improve our ability to make and use tools under a variety of conditions.

Want to know more?

• Pruney digits help people get a grip: Wrinkling may have evolved as an adaptation to wet conditions
• Tanya Lewis 
• Science News Web edition: January 9, 2013 Print edition: February 9, 2013; Vol.183 #3 (p. 11) 
• [Brief article explaining the recent development in plain English.]
• my-ap.us/XwFvGn

• Water-induced finger wrinkles improve handling of wet objects.
• K. Kareklas et al.
• Biology Letters. Published online January 8, 2012.
• [Journal article outlined proposed theory.]
• my-ap.us/WbV5K9

• For ancient hominids, thumbs up on precision grip.
• B. Bower  
• Science News, Vol. 177, May 8, p. 15. 
• [Brief related article on evolution of human grip.]
• my-ap.us/11zYCYt

• Fingerprints filter the vibrations fingers feel
• L. Sanders.
• Science News, Vol. 175, February 28, p. 10
• [Brief related article on sensory function of human epidermal friction ridges.]
• my-ap.us/YksrEP