Modern humans are a handy bunch — much handier than the first handy man, Homo habilis:
Handy man made tools, but they were crude. That could be because his wrists and hands were still pretty ape-like. Now, apes make tools. Scientists have trained a bonobo, called Kanzi, to do that. But Kanzi’s not much good at it.
“He just can’t get the motions down,” Williams says. That’s because he can’t grip the stones, his thumbs aren’t long enough and his fingers are too long and he’s clumsy. He can’t move his wrists — he can’t extend his wrist and get this important “snap.” He makes a mess.
An ape’s brain is up to the task, but his anatomy isn’t. He doesn’t have the hands. It took millions of years of evolution to produce the hands of a skilled flint-knapper like [Dennis Sandgathe, an archaeologist from Simon Fraser University in Canada].
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On an office table, Orr has laid out the skeletal hands of three apes and a human. The apes’ hands are enormous — the orangutan’s is like a catcher’s mitt.But their thumbs are tiny and splayed out to the side; the fingers are long and curved. They look powerful, but Orr says the strength runs vertically, from the wrist up through the fingers. That’s good for hanging on tree limbs, but not for much else.
The human hand is smaller, and it works differently. Orr hands me a two-foot-long club to illustrate.
“Here, try to hold this without using your little finger, and just using those other digits,” he says. That’s the way an ape might hold it. I make to swing it but realize it will fly out of my hand if I do.
The strength in my hand extends across my palm. My thumb is stronger, and so is my pinky. I can wrap that thumb over my other fingers and then secure the grip at the bottom with my pinkie. An ape can’t manage that very well.
And my opposed thumb and wider fingertips also mean I can grip a round stone — like a hammerstone — with more control than an ape can.
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“When I flip the arm over so that the palm is up you can see, underneath these tendons, that we have just a ton of muscles that are just in our palms that help us finely move our fingers.”It’s a spider’s web of muscles and tendons under the skin, many of them unique to the human hand. The hand’s exquisite architecture allows us to play Bach, shuffle a deck of cards, or write poetry — the things we often think of that define us as human. And all it took to get it was a few million years of whacking two rocks against each other.