Re: The brain and the hand

Scott Badger (
Fri, 6 Aug 1999 07:39:09 -0500

> From: Eliezer S. Yudkowsky <>
> >The evolution of human intelligence had nothing to do with tool use,
> >IMHO. Human intelligence was the result of social competition for
> I don't think so, all animals have social competition for mates, but only
> 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
> be as important as it is; a much more intelligent deer wouldn't have a
much greater
> survival rate. The fossil record gives some support for my claim, 3
million years ago
> Lucy was fully bipedal and had a hand with a opposable thumb, but her
brain 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.
> John K Clark

A couple of years ago I saw something on TLC or TDC that explored one anthropologist's theory that it had to do with heat. My memory is fuzzy on this, as it is on many things, but it had to do with the fact that quadrapeds exposed a lot of bodily surface area to the hot savannah sun. The anthropologist tried to demonstrate that the brain, an organ which requires a tremendous amount of cooling relative to the rest of the body, was essentially constrained from growing any larger until bipedalism came along and significantly lowered the amount of surface area exposed to the sun. I'm not up on recent evolutionary thought so for all I know this is a predominant idea at this point. I'd be interested to hear what some of the competing theories might be.

Scott Badger