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Evolution of human diet
Ward Nicholson (wardnik@southwind.net)
Wed, 22 Nov 1995 10:42:14 -0600
I'm new to this newsgroup and am curious about the evolution of human
diet. My interests come from the fact that I coordinate/publish a small
(very small) newsletter/discussion group on natural foods, meat-eating vs.
vegetarianism, eating raw foods vs. cooked foods, etc. Many of the people
who subscribe/participate are vegetarians (I used to be myself but no
longer am) and are convinced that homo sapiens was "originally" (whatever
that means) a vegetarian species, even a so-called fruitarian species that
ate nothing but raw foods and so that is what we should be doing today.
Starting from the premise that health is far more likely if we eat foods
that are in line with our biological adaptation, one idea would be to
discover just what humanity's "original" or "primitive" diet was and
follow it. Well, you would not believe (yes you would!) how many different
ideas there are from armchair philosophers about just what such an
idealized "original" diet is supposed to consist of, usually being some
variation of all vegetarian raw foods, and that meat-eating was a
"degeneration" from some pristine state.
Well, once I decided to look into the evolutionary story myself (as a
layman), I of course discovered a very different picture. I was amazed to
find, however, over the last couple of years as I have investigated the
evolutionary picture that dietary research seems to be a (relatively)
small area of interest for most anthropologists/paleontologists. I can't
figure out if it is because it's hard to find actual dietary physical
evidence that survives to be studied so there's simply not much to say, or
if it's because people have such subjective and strongly held beliefs
about food they don't care to investigate it much.
Anyway, I wondered if people here could fill in some gaps for me. The
sequence for a dietary timeline as best I have been able to piece it
together (none of it was all together in one place, I had to stitch it
together myself from several different sources), is as follows:
65,000,000 to 50,000,000 B.P. - First primates in human evolutionary line
resembling today's mouse lemurs, bush-babies, tarsiers, etc., eating
largely insectivorous diet.
50,000,000 to 30,000,000 B.P. - Shift in diet for these primates to
primarily frugivorous, with great variance as to other items in diet, such
as insects, meat, and other plant foods (roots, shoots, etc.) besides
fruits.
30,000,000 to 10,000,000 B.P. - Stable persistence of above pattern.
circa 7,000,000 B.P. - Meat begins to account for greater importantance in
the human line as it diverges from the last common ancestor with modern
ape family.
circa 2,000,000 to 1,700,000 B.P. - Homo habilis subsists via hunting,
gathering, scavenging. Seems to be continuing debate over how much of the
meat was obtained by outright hunting vs. scavenging kills by other
predators.
1,700,000 to 400,000 B.P. - Homo erectus' hunting activity increases over
homo habilis so that meat assumes greater importance in the diet. (How
much importance never seems to be specified.) First in human line to
control and use fire (POSSIBLY FOR COOKING? This is my own question never
seemingly broached in the anthropological literature looking at this time
period). Date for discovery/control of fire seems exceedingly vague, with
estimates going back as far as 1.4 million years ago, but maybe only as
recently as 500,000 years ago.
1,000,000 B.P. - Spread of homo erectus to colder Asian/European climates
and more probable beginnings of use of fire/heat for cooking and
processing foods (as best I can tell "reading between the lines.")
40,000 B.P. - Behaviorally modern human beings, stone and bone tools, etc.
40,000 to circa 12,000-10,000 B.P. Last period prior to advent of
agriculture during which modern humans universally subsisted by hunting
and gathering.
35,000 to 15,000-10,000 B.P. Cro-Magnons perfect big-game hunting and meat
temporarily assumes great importance in the diet, perhaps up to as much
50% of total food consumption during this time period.
12,000 to 10,000 B.P. Advent of agriculture coincides with rapidly
increasing human population. Infectious disease rates rise dramatically
beyond those prior to agriculture. (Big question: Is this/could this be a
result of the shift in diet to agriculturally domesticated and processed
foodstuffs as opposed to eating more wild foods? The usual investigations
seem to look primarily at population concentrations inducing higher
communicability of disease while ignoring the role of changing foodstuffs
the species did not evolve on lowering resistance to infectious
organisms.)
5,000 B.P. - Agriculture supplants hunting/gathering for all except
isolated primitive tribes.
In the book The Paleolithic Prescription, authors Eaton, Shostak and
Konner state that while previous to agriculture the human diet may have
averaged something like 65% plant/35% animal, that since then it has been
more "vegetarian" than ever before (perhaps something like 90% plant/10%
animal on average) due to the importance of grains in feeding large
concentrated populations.
The above timeline is the most DETAILED picture I have been able to piece
together of human dietary evolution. That leaves a lot of gaps I am still
curious about. Does anyone know or care to guess:
1. Has anybody ever tried to determine how quickly or how long it takes in
evolutionary time after shifts in dietary patterns begin to take place
before the population as a whole becomes "adapted"? Maybe this seems like
an obtuse question coming from a layman. But here's my interest: Many of
the people writing in to my many-to-many newsletter who are vegetarians,
when confronted with the evidence for heavy meat-eating by Cro-Magnons
35,000 years ago, like to finesse the issue by saying we should go back
even further to determine the kind of dietary patterns that humanity is
best adapted to. In other words, they don't think (or want to believe)
35,000 years is enough time to become adapted to heavy meat-eating. They'd
rather look at time periods further back when the evidence for meat-eating
is not as abundant.
2. This brings up another question. If we assume that evolutionary
adaptation to dietary behavioral changes is "fluid" or involves a "time
lag," then how do you make any sort of determination as to what spectrum
of foodstuffs is the "optimum" where health and freedom from disease is
concerned? Obviously, to say, humanity is "omnivorous," while true, is a
ridiculously crude answer. Yet you have to have a certain amount of
evolutionary variation to allow for survival under changing food
conditions. Modern nutritional science, though, is beginning to show that
even if omnivorous you can't just eat anything and expect to stay healthy.
What light can the evolutionary picture shed to counterbalance current-day
clinical experimental findings that say, for instance, first (15 years
ago) "carbohydrates are bad" and (nowadays) "eat 70% carbohydrates in your
diet."
3. Another question: A certain percentage of individuals are wheat and/or
lactose-intolerant. Grains and dairy products being with us only since
extremely late in our evolution (last 10,000 years for dairy),
grain-eating since perhaps 30,000 years ago in the wild, more heavily in
the diet only since 10,000 years ago, does that say that our adaptation to
these foodstuffs (as a population) is as of yet only partial?
4. What about the inception of cooking? Natural-food types say we would be
better off eating all uncooked foods, "since that's how they occur in wild
nature." But many who try an all-raw diet for any length of time (I've
tried before) find they do not thrive and need to reintroduce foods edible
only (or at least usually only by cooking--potatoes, squashes, grains,
etc.). (Of the people in my correspondence group, perhaps only 10-20% are
able to do well eating a totally unfired diet.) Yet since there has been
little (none that I know of) modern-day nutritional experiments set up
with control groups to see what happens with groups eating "all-raw" foods
vs. cooked foods, the door is wide open for the inflexible raw-food types
to make appeals to subjective "wild nature" justifications if there is no
interest on the part of anthropologists at looking into the question of
when did the use of fire start for cooking foods, and did it increase not
only survival chances but our health as well.
Well, that's more than enough for one post. Any interest out there in all this?
--Ward Nicholson <wardnik@southwind.net>
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