Experiment bucks finding that ridges help fingers grasp
Scientists have lost their grip on understanding why fingers wrinkle when soaked in water. An independent research group was unable to reproduce the finding that the wrinkles improve handling of wet, slippery objects.
Last year, researchers had 20 adults handle dry or wet glass marbles and lead weights with plump or pruney fingers (SN: 2/9/13). Volunteers transferred the objects from one container through a slot and then into another container. Wrinkled fingers allowed the study volunteers to move wet objects 12 percent faster than dry and plump fingers could.
But when researchers led by Gary Lewin at the Max Delbrück Center for Molecular Medicine in Berlin-Buch, Germany, conducted a very similar study, the watery advantage washed up.
In the new study, published January 8 in PLOS ONE, 40 volunteers transferred objects in a similar way, but the materials differed: in addition to glass marbles, they included rubber marbles, plastic dice and brass weights. Researchers found no difference in wet-object handling time when the volunteers’ fingers’ were smooth or wrinkled.
The team suggests that, contrary to the earlier study’s conclusion, finger wrinkling from water soaking is not an aquatic adaption but an incidental response to warm water.
J. Haseleu et al. Water-induced finger wrinkles do not affect touch acuity or dexterity in handling wet objects. PLOS ONE. Vol. 9. January 8, 2014, p. e84949. doi: 10.1371/journal.pone.0084949.
K. Kareklas et al. Water-induced finger wrinkles improve handling of wet objects. Biology Letters. Published online January 8, 2012. doi: 10.1098/rsbl.2012.0999.
T. Lewis. Pruney digits help people get a grip. Science News. Vol. 183, February 9, 2013, p. 11.