Let me clarify.

Milton K was NOT recommending a vegetarian diet.  Indeed, she is on record
as saying (1998) "I am not advocating a vegetarian diet". She even wrote an
entire paper (1999) arguing that animal food played an essential role in
human evolution and that "the routine inclusion of animal foods in the diets
of weaned children seems mandatory".

I quoted her at length to prove that there was no consensus amongst
scientists as to the actual percentage of animal food in Homo's diet.  Our
ancestors left Africa about 50 Ky ago, at which time our evolution as a
species was largely complete.  So the diet of those of our ancestors who
migrated to high latitudes, on which Cordain's 70% estimate was based, is
much less relevant than the diet of our African ancestors who lived 50 Ky ago.

What do we know of the diet of our African ancestors 50 Ky ago?  Well, we
have the example of the present day !Kung San, who eat 33% animal food. But
do they occupy their original lands?  They do not.  In the past 2000 years
they have been driven to marginal lands by Bantu-speaking farmers who have
seized the most fertile soils for their crops.

Is this push to marginal lands likely to have increased or decreased the
San's intake of animal food?  I do not know.  More fertile lands support
both a richer plant life and a more abundant animal life.  But we certainly
cannot deduce that it was 33%.  In short, the study of present-day
hunter-gatherers gives us insufficient data from which to deduce the
proportion of animal food in Homo's primitive diet.  Milton's point was that
it is unsafe to draw conclusions.

Rick asks that we not "get picky with percentages".  But percentages are the
whole point.  Our early ancestors almost certainly ate SOME animal foods,
just like present-day apes & baboons.  The question is, how much and what?

Cordain makes a plausible case that early man relied heavily on animal
brains and bone marrow, scavenged from the leftovers of carnivores who
lacked the weaponry to crack open skulls and large bones.  Brains are high
in omega-3 fats and bone-marrow is high in mono-unsaturated fat.
Fortunately, for those of us who do not relish raw brains & marrow, our gut
is flexible enough to source the nutrients elsewhere.  I agree that this
would be difficult on a purely vegetarian diet.  I also agree that we can
thrive on 70% animal food.  But I find no scientific consensus that 70% is
either the dominant historical percentage or the ideal one.

Cheers
Lance