What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern?-- from The Origin of Species by Charles Darwin, quoted by Carl Zimmer in a pleasant note about hands.
I am reminded of something from Jonathan Kingdon (2003) quoted in my forthcoming book:
When I watched possums expertly finger-drumming bark to locate larval burrows or maneuvering witchetty grubs out of holes and into mouths, I suspect I that was witness to some of the most ancient skills that distinguish not just possums but, maybe archaic mammals as a whole. Touching, gauging, gouging, probing hands and fingers are so closely coordinated with smelling, seeing, hearing, and tasting that their refinements have as much to do with serving senses and feeding appetites as with clambering through branches. If, as most evolutionary biologists would contend, human anatomical history is made up of successive increments, perhaps we need look no further than our hands to discover a legacy that could stretch back 140 million years.