Let me be clear that I was aware that evidence for use of fire goes back a
half-million years or so.  The careful reader will note that I was
specifically referring to evidence of use of fire -for cooking-.  However,
as I cannot remember where precisely I got that little factoid about 25,000
years, I'll withdraw the comment in face of greater knowledge and will
humbly seek the Stahl paper for further enlightenment.

If the protein absorbability of raw rice is normally 25%, then that means
you could live for a while on the stuff, if not very well.  It would
probably be a safe bet that if forced to go on such a regimen the
metabolism might be able to adjust somewhat given time.  But if we can also
posit that wild grains are even less rich in calories and more full of
indigestible bulk than modern artificially grown and bred stuff, then most
likely our ancestors didn't eat much grain, not as a staple anyway.
Nevertheless someone had to figure out that it was worth cultivating, so
likely someone was chewing on it now and then.  So referring to cereal
grains as "not digestible" by humans without cooking is probably not the
most precise way of phrasing things.

As for my experimenting with eating raw grains and beans and reporting the
results: Doctor Cordain, I am inspired by your suggestion, and in the
interests of science am starting immediately.  I will be saving all my
post-prandially produced materials for the next two weeks in tightly sealed
thermos containers.   However, I suspect I would lack sufficient
objectivity in the area of gas spectrum analysis; after all, like most
people, I am quite convinced that my natural output has no particularly
redolent effluvium.   Knowing your own keen interest in this subject area,
I will dispatch my un-fossilized coprolite on a daily basis to the Colorado
State University for your (I am sure) assiduous and fully objective
evaluation.  Perhaps we can then co-publish a paper on the results.

Yours in science,

Dean Esmay, Esq. Q.E.D. P.D.Q.