Somebody wrote:

>>>From what I understand, brain size directly relates to intelligence, at
>>least among contemporary humans.

If you assume that, that you'd have to claim that men are more intellegent
than women. The brain of a man is average 100 cc bigger than that of a
woman. But studies show, that women in average are (at least) as intellegent
as men.
And you'd have to explain why a genius, like Einstein had a relative small
brain (found after hist death, in volume.

On Wed, 5 Jun 2002 13:40:47 -0700, Ken Stuart <[log in to unmask]>
wrote:

>The major point is:
>
>" The data that human brain size has fallen 11% in the last 35,000
>years--with the bulk of that decrease (8%) coming in the last 10,000
>years.... that
>increasing brain development earlier in human evolution is correlated
>positively with the level of animal food in the diet.

Why did then human brain size fall (by 3% according to your numbers) in a
time, where animal consumption increased a lot,
in the time between 35000 to 10000 BC.
At last that was the highest ice age,
and in northern areas plant food was rare. While in the (more important)
southern places (dry savannah) humans showed greatly improved hunting
skills?
(Improved skills: better weapons, better stone blades, bows and
arrows, fishhooks, simply smarter people)

My guess is as follows:
The really big encephalisation happened in doubling and threefolding the
brain size from 2-1 million years ago. Caused by better availability of a
superior high energy brain food: carbohydrates of savannah USOs (tubers).

Brain size reached a peak in neanderthals (which are not known to hav had
particular intelligence - few developements in 100000's of years).
Because of the increased brain cell *redundancy* necessary to better survive
brain shocks (concussion) in the more frequent dangerous hunting episodes
against the more dangerous big iceage mega-beasts.
The increase was (I think) primarily a volume increasement caused by more
glia insulation cells and not in number of brain cells (men seem to need
their bigger volume for this same purpose, compared to women)

Later brain size could decrease a little (11%) as humans became smarter,
with less brute force attacks as neanderthals did, better tools and a better
environment knowledge.

>Finally, in what will be
>controversial to raw-fooders, Aiello and Wheeler, after arguing that the
>first major increase in encephalization was due to increased consumption
>of animal foods, next propose that the second major increase in brain
>size (with the appearance of archaic Homo sapiens) was due to the
>appearance of cooking practices.

The only explanation, why animal foods would support encephalisation
is better availability of long chain  fatty acids like DHA and AA.
IMO weak, but supported by L.Cordain.
Energetically animal food is not a good deal.

A very interesting reading on this topic is Dr.Wrangham's "The raw and the
stolen", who assumes the same effect from cooking to have happened
earlier, 1.9 MY ago.

regards

Amadeus