On Tue, 8 Aug 2000 11:23:47 -0400, Dena L. Bruedigam <[log in to unmask]>
wrote:
>... The point made by the anthropologist was that if they
>continued to eat a vegetarian diet they would need more guts, and more gut
>development meant less brain development. ..

That's the expensive tissue hypothesis.
Keeping a longe gut active needs more energy than a shorter gut.
If you shortened the gut, some energy is left and this energy can be used by
a larger brain. Our large brain now uses 25% of resting energy instead of
some 9% in smaller primates.
Fine and logical?

But animals don't have a certain long gut just to spend energy.
Any gut is optimized to gain the maximum of nutrients out of food.

A bigger brain uses more energy, so we just needed to eat more food
and the capability to absorb it.
Gorillas eat most of the day, this is a sign that they are approaching
a limit with their leaves only diet.
This points toward a denser diet.

If humans got shorter guts as gorillas have (actually they are hard to
measure in a homo erectus sceleton) this is a sign that they got
food which is digestable in a shorter gut.
Essentially this means less space for fermentation of cellulose.
This points towards a denser diet too.

The human gut is longer as of a carnivore (we are well equipped
to digest plants as opposed to cats). Actually the long gut is a
drawback when eating meat only, because of the too long resting time
for the excrements in there.

The denser diet can have been both, animal matter or denser vegetables
(to be exact, food with less cellulose to be fermented).

To eat the 2400kcal required today (> 500kcal for the brain) you needed to
eat:
16.0 kg of leaves (here salad)
 3.4 kg of mango
 2.3 kg of tuber (here sweetpotatoe)
 2.1 kg of rabbit
 1.6 kg of more fatty meat (6% fat)
 0.4 kg of nuts

The brain is dependent on fuel in the form of carbohydrates.
The meats have zero carbohydrates, but it
could be converted from very much protein of it.
The nuts have parts (about 700 kcal) in form of carbohydrate.

We don't know what it was.
You'll gess my estimation, everybody can make it's own judgement.

regards

Amadeus