Another wrinkle in the wrinkled-fingers investigation

A new German study snaps its fingers, metaphorically, at recent studies of human finger-wrinkling:

Finger Wrinkling (2014, not gripping)

Water-Induced Finger Wrinkles Do Not Affect Touch Acuity or Dexterity in Handling Wet Objects,” Julia Haseleu, Damir Omerbašić equal,  Henning Frenzel, Manfred Gross, Gary R. Lewin, PLoS ONE, 9(1), 2014, e84949. (Thanks to Achim Reinsdorf for bringing this to our attention.) The authors, at Max Delbrück Center for Molecular Medicine, Berlin-Buch, and Charité Universitätsmedizin, Berlin, Germany, explain:

“Here we investigated the idea that wrinkling might improve handling of wet objects by measuring the performance of a large cohort of human subjects (n = 40) in a manual dexterity task. We also tested the idea that skin wrinkling has an impact on tactile acuity or vibrotactile sensation using two independent sensory tasks. We found that skin wrinkling did not improve dexterity in handling wet objects nor did it affect any aspect of touch sensitivity measured. Thus water-induced wrinkling appears to have no significant impact on tactile driven performance or dexterity in handling wet or dry objects.”

Finger Wrinkling (2011, gripping)

Are Wet-Induced Wrinkled Fingers Primate Rain Treads?” Mark Changizi, Romann Weber, Ritesh Kotecha and    Joseph Palazzo, Brain, Evolution and Behavior, epub 2011. (Thanks to Leland Roman for bringing this to our attention.) The authors, at AI Labs,  Boise, Idaho , USA, report:

“Wet fingers and toes eventually wrinkle, and this is commonly attributed by lay opinion to local osmotic reactions. However, nearly a century ago surgeons observed that no wrinkling occurs if a nerve to the finger has been cut. Here we provide evidence that, rather than being an accidental side effect of wetness, wet-induced wrinkles have been selected to enhance grip in wet conditions.”

Finger Wrinkling (2013, gripping)

Water-induced finger wrinkles improve handling of wet objects,” Kareklas K, Nettle D, Smulders TV, Biology Letters, 23 April 2013 vol. 9 no. 2. The authors, at  Newcastle University, UK, write:

“Upon continued submersion in water, the glabrous skin on human hands and feet forms wrinkles. The formation of these wrinkles is known to be an active process, controlled by the autonomic nervous system. Such an active control suggests that these wrinkles may have an important function, but this function has not been clear. In this study, we show that submerged objects are handled more quickly with wrinkled fingers than with unwrinkled fingers, whereas wrinkles make no difference to manipulating dry objects. These findings support the hypothesis that water-induced finger wrinkles improve handling submerged objects and suggest that they may be an adaptation for handling objects in wet conditions.”

BONUS: Die Welt offers its take on developments.