From: Ray Recchia (rrecchia@frontiernet.net)
Date: Fri 24 Oct 2003 - 10:29:42 GMT
At 09:05 AM 10/24/2003 +0100, Derek wrote:
> > One question is why we were the only mammal to go so
> > far?
>
>I used to wonder why, for example, there are no
>reptile lineages that have evolved larger brains -
>some did get as far as being bipedal and social. I
>vaguely remember that the answer was something to do
>with warm bloodedness, but I wonder if that argument
>still holds in the light of more recent ideas about
>warm bloodedness in dinosaurs?
>
>Is there a physiologist in the house?
I've read over and over that brains are very energy expensive to operate. I
think it is something like a ration of the brain being only 2% body weight
but consuming 20% of the calories. I can recall (but not find) an article
that hypothesized the calorie demands of a larger brain could not be met
until we became more carnivorous.
I think that the presumption has always been that tool use and greater
socialization required larger brains and that the fitness reward
compensated for the increased cost in calorie consumption.
Ray Recchia
Ray Recchia
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