<i>Not everyone is gripped by the new theory. "This hypothesis is unjustified", says Xi Chen, a biomechanical engineer at Columbia University in New York. Chen thinks that the wrinkles have a simpler cause: when fingers are immersed in hot water, the blood vessels tighten and the tissue shrinks relative to the overlying skin. This contraction causes the skin to buckle. "It's a classic mechanics problem," he says.</i><p>Ugh. Explaining the mechanism behind a behavior is not an argument against its purpose!<p>Scientist A: I think polar bears evolved white fur so they'd be camouflaged in the snow.<p>Scientist Crazy Pants: No silly, polar bears have white fur because their hair follicles contain keratin and are hollow.<p>Scientist A: I'm going to kill you.
Surely if it were that, then fingers should wrinkle faster?<p>If I stick my hand in water then it gets wet immediately, but doesn't wrinkle for... what, fifteen minutes? And that's warm water -- cold water (like practically all the naturally-occurring water in the world) takes a lot longer.<p>And then, I can dry my fingers much faster than I can un-wrinkle 'em. Surely the circumstances in which an ancestral human would:<p>a) Spend fifteen or twenty minutes in the water, then<p>b) Need to pick up something vitally life-preserving within the next few seconds<p>would be sufficiently rare that it probably wouldn't have been a major selection pressure?
<i>Scientists have known since the mid-1930s that water wrinkles do not form if the nerves in a finger are severed, implying that they are controlled by the nervous system.</i><p>That is the amazing part, if it's not a merely mechanical process. A bit further down they mention poor circulation also impeding wrinkling, so it may have something to do with control of capillary blood vessels.
Articles like this satisfy some tiny general interest (<i>wrinkles! neat!</i>) but then squander any good will by predisposing the public to completely misunderstand evolution.<p>The trait may stick around if it's useful, but it didn't evolve "for a reason."
When I grip something with wrinkled fingers, I get the impression that the contact surface compresses and smooths out the wrinkles. So they don't act like treads. If I grip a glass with wrinkled fingers and pour water over my fingers, I would expect the water to go around the contact surface - not be channeled through the finger wrinkles.<p>For this hypothesis to make more sense, I would expect to see "micro-wrinkles" not the large compressible ones which I actually do.