Re: The brain and the hand
Fri, 6 Aug 1999 07:42:13 EDT

In a message dated 99-08-06 00:44:10 EDT, (John Clark) wrote:

> I don't think so, all animals have social competition for mates, but only
> humans
> evolved intelligence. I think it's because we have two free limbs and
> so have the most important tool of all, the hand, without it intelligence
> wouldn't
> be as important as it is; a much more intelligent deer wouldn't have a
> greater
> survival rate. The fossil record gives some support for my claim, 3
> years ago
> Lucy was fully bipedal and had a hand with a opposable thumb, but her
> wasn't
> much bigger than that in a modern chimpanzee.
> Bipedalism is important because a hand that's good at locomotion is not
> good at manipulating objects, but why did we become bipedal? Evolution
> has no foresight so a desire of a big brain can't be the reason humans
> walked upright, there are lots of theories but nobody knows for sure.

You know, although I know there are subtle and important distinctions between the human hand and those of other primates, I've also come to wonder about the "opposable thumb breakthrough" meme. As I write this, my lemur Darwin is sitting on my desk holding a pen with his hand and using it to scratch his ear. As he does about one time in ten, he's got his thumb opposed to his fingers as he grasps the pen (I'm really not making this up, he's looking at me now, wondering why I'm grinning at him so much). A chimp will use her thumb in an opposed fashion almost as often as a human, from the observations I've made in zoos and on video. I agree that it's much more a function of the combination of BIPEDALISM with the wetware behind the hardware, than the hand alone. The major breakthrough that happened with Australopithicus was freeing up the hand. As you say, John, the big question in primate evolution is what pushed us upright.

Looking forward to some bipedal, manual-to-manual interaction at EXTRO4 in a few hours . . .

     Greg Burch     <>----<>
     Attorney  :::  Vice President, Extropy Institute  :::  Wilderness Guide   -or-
                         "Civilization is protest against nature; 
                  progress requires us to take control of evolution."
                                      -- Thomas Huxley