Wally Day wrote:
> For
> instance, we can assume that all humans can tolerate
> both meat and plant foods in various ratios - some
> predisposed to eating meat, others to eating plants.
> During an extended ice age period, wouldn't natural
> selection simply eliminate most humans who exhibit a
> very low tolerance for eating meat - therefore,
> increasing the number of "meat eaters" in the general
> gene pool?

I don't think that there is a special genetic adaption necessary for
large scale meat eaters. All mammals do "digest" their own tissues
everyday and in circumstances of starvation. All unneccessary amino acids
are downgraded to glucose anyway.
It's just the extent, the excreting capacity and gluconeogenesis capacity
that changes for a meat eater.
I think if there's an adaption necessary, it happens within a lifetime
by enlarging the kidneys, liver, and producing more or less enzymes of a
certain kind.

Much "adaption" will be in cultural habits. Like the habit to drink enough,
leave-out/includeing of liver or fish.

A real adaption pressure would be the *dependance* on several items, like
Vitamin C, folic acid, vitamin E. Some stuff we are dependant on is really
little in the northern meat diet.
vitamin C storage capacity or alternatives will have constituted a real
selection topic for these north people.

Obviously all of or constraints could be met, even by the inuit diet.
Even our vitamin C dependance anomaly.
At which cost in health status/aging - we don't know.

The same "bottleneck" situation happened later on, as Todd points out,
when other bottlenecks hit the neolithic culture.
Then the bottleneck may have been vitamin A or again C.

The LNA (alpha linoleic acid) shortage in grains have been overcome
by domesticating flax. It was first used as an oil plant (not textile).
This was around 6000 BC, early enough for the wave of 4400bc to middle
europe, but much later than the neolithic revolution in the orient (after
10,000 bc).

On Tue, 31 Jul 2001 09:05:05 -0400, Todd Moody <[log in to unmask]>
wrote:

>.. recent work in
>genetics indicating that all modern Europeans are descended from
>a very small breeding population (No more than a few hundred) who
>left Africa about 60,000 years ago to endure the rigors of the
>last ice age.  This should at least be highly relevant to those
>of European descent.

Basically all "whites".

>On the other hand, the 10,000 years or so
>since the advent of agriculture are not neglible either.  They
>have created very different selection pressures, but no less
>intense.

Besides this proposed small northern gene pool there existed a large gene
pool in warmer areas like aethiopia (it has 70 languages today).
At last with the onset of the neolithic culture in europe, these
people came in and mixed again. Maybe less in areas not suitable well
for agriculture, like Finnland.

There's been a long discussion how the take-over of the neolithic culture
in europe worked. Was it a displacement or was it an assimilation.
Recently a study (on the male y chomosom) resulted that european
populations share to 80 or 60 or 70 percent a very similar pattern, while
the others differ.
This suggests that most of the paleolithic h/g people have been assimilated
or converted and stayed on their area. With a little mix of some 30% from
immigrating people.

>This is why I think it's a mistake to consider all
>humans metabolically the same.

yes.

Amadeus Schmidt-Philipp