Cabinet of Wonders provides us with everything you’ve ever wanted to know about fingerprints, but were afraid to ask. I particularly enjoyed this tidbit:
Spider monkeys, whose prehensile tail-tips are so sensitive and flexible that they can pick a dime up off a floor, also have prints on the bare spot at the end of their tails. Since the tails are used not only as a sort of third arm when swinging in the trees (as a safeguard from falling), but often supports the entire weight of their bodies while they feed, this would make sense: fingerprints, and other places with “friction ridges” – the volar regions – generally tend to occur where one needs to grip something. This can mean gripping an object to keep from dropping it, or (as in the case of trees) to keep it from dropping you, or simply to keep your feet steady on the rocks so you don’t fall off a cliff.
But how does it work?