Not wanting to repeat points already made, I'll skip to a few
salient items...

On Mon, 7 Aug 2000, Amadeus Schmidt wrote:

> >I doubt it.  Cordain's kangaroo study suggests that even in arid
> >Australia there is still a good deal of fat to be harvested from
> >the carcass of even a lean animal like a kangaroo.
>
> Do you  doubt my statement aboute fat availability in arid climates,
> or the low genetic influence of arctic-like environments?

The kangaroo lives in arid climates.  I think the more typical
paleolithic environment was neither arid nor arctic.  As Ray has
indicated, the Ice Age caused climate changes that produced large
regions of "steppe-tundra" of varying levels of wetness.  Yes,
the ice caps expanded, but I don't think many people were living
on them.  As I've said before, I think human viability in arctic
conditions depends on mastery of fire.  At any rate, my guess is
that the bulk of the human population spent a lot of time in
climates that were cool and damp, perhaps a lot like conditions
in large parts of England and Scotland today.  There is
plenty of ground cover and shrubbery, but not too much forest.
The winters were cold, but not so cold as to have much snow
accumulation.

In that sort of environment there would be a variety of sources
of animal food of various sizes, including waterfowl and
ruminants, plus various small but edible creatures, such as
turtles, frogs, etc.  And of course there would be edible
vegetation as well, including (when in season) tubers and nuts.
Fruits and berries would be only transiently available.

My idea is that it is precisely the "quest for fat" that lured
humans into cooler and cooler environments.

> Now that Cordain computes 8.2% overall fat for that kangaroo
> (instead of 4% with the wild unugulates before) the numbers are changed
> bit (while fat will still vary from season to season).
> Now we have 46:54 calories from fat to from protein.
> While (always according to cordaine) from 35% cal from protein
> begins to be toxic (this is "rabbit starvation" i suppose).

I guess.  It seems to me that the "toxic" level of protein should
be based on body weight rather than percentage of calories; I'd
like to find out about that.

> But most plants provide their energy without burdening much protein "stress"
> on the kindneys and liver. While still provinding abundant of protein
> for structural purposes (>> RDA).
> (we are not endangered by cookies and cakes here)

This "stress" is just the organs doing their job.  Tubers
"stress" the pancreas.  I've already argued that as far as I'm
concerned the RDA for protein is only enough to prevent protein
deficiency problems, but humans thrive on considerably more.  The
fact that contemporary hunter-gatherers get about twice as much
protein as most civilized people is a clue, I think.

> Sure maybe. My guess is, that plants would have been the preferred
> caloric source, as long as available. For the notes reasons.
> But besides nuts i only come to tubers as a denser plant food.

I agree that nuts and tubers would have been exploited when
available.  It would be interesting to find a population of
hunter-gatherers that actually *preferred* tubers to animal
foods, if both were available.  In North America, the "duck
potato" is widely available, but as far as I can tell most native
Americans still made extensive use of meats.

If your view is that HGs only turn to animal foods as a last
resort, I don't think there's much support for that.  Certainly
there are places in the world where one could get enough energy
from plants alone, all year.  But even in those places, nobody
does so.

> >Then nuts are going to be problematic, since most of them are
> >overwhelmingly composed of MUFAs.
>
> Where do you see a problem with too much EFAs? They can be nurnt as well.

I said MUFAs, not EFAs.  You claimed that MUFAs are a problem
because they too compete with EFAs for enzymes.

> Thats the case for some nuts. Notably hazels, which are cheap too.
> And also cereal grain foods. This is what i think why the early neolithic
> people, who had with grains lentils and flax were so successful.
> Inflammation could be quite a problem i suppose.

I disagree.  There is no evidence that neolithic people were
successful because they were healthier.  Rather, they were
successful because they were more numerous.

> >This is incorrect.  More recent work indicates that dietary AA
> >has little or no effect on prostaglandins.
> Can you give some reference for this? And also what did "persuade you"
> that dietary AA wouldn't be a problem?

Look at the GJ Nelson et al. studies in _Lipids_, vol. 32 (1997).
These studies involved *massive* supplementation of dietary AA in
normal people -- the equivalent of about 25 eggs per day.  The
additional AA was well tolerated, and the researchers found that
dietary AA is preferentially taken by red blood cells, which lack
the enzyme (cyclo-oxidase, I think) needed to produce the
inflammatory prostaglandins.  This is an area where Barry Sears
made a mistake.  While *endogenous* AA may be your "worst
biological nightmare," as he puts it, dietary AA in amounts
likely to be encountered in an ordinary diet is not.

> >Then the populations mentioned above should be very sick.  Why
> >aren't they?
> Because membranes prefer 18-chain long FA.
> And more important, the have probably enough of EFA sources.
> Zebu cattle are very low fat and also high in EFA if i recall right.

Again, if this is based solely on muscle fat it is probably
misleading.

> >But if your theory is right, animal fats should interfere with
> >glucose tolerance, by making membranes less permeable to glucose.
> >Why isn't that so?
> Maybe your studies have included eather enough EFAs in the diet
> or sources other than 18:0 and 16:0 e.g. by supplying fish as animal
> or dariry as fat or added supplements.

No.  Wolfgang Lutz, for example, specifically urges his patients
to eat fatty meats.  And dairy fats, as we already saw, are
loaded with long-chain saturates.  In the Hays study, 90% of the
fat consumed by the patients was saturated fat.  Their overall
protein:fat:carb ratio was 30:50:20.  Main fat sources were meat
and cheese.  The Hays study was a year long; Lutz tracked some of
his patients for many years.  This is important because while
there are lots of theoretical objections to these sorts of diets,
and short-term clinical trials, there aren't many long-term
studies.

So, theory says that people on these high-fat diets with lots of
saturates should be getting sicker.  The actual facts point in a
different direction.  This suggests that the theory needs work.

Todd Moody
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