Uponcontinuedsubmersion inwater, the glabrous skinonhumanhands andfeet formswrinkles. The formation of thesewrinkles 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
The experiment and the discussion in the paper were clear...
"This finding shows a clear advantage of having wrinkled fingers
when manipulating submerged objects, but not dry objects." (Kareklas et al 2013:2)
Kareklas, K., Nettle, D., Smulders, T. Water-induced finger wrinkles improve handling of wet objects. Biology Letters 9:20120999, (2013).
The key question is whether the same response is observed in our closest relatives, the great apes.
WHHE predict that this effect would not be as strong in chimps and gorillas than in humans.