Further, "Because of the considerably harsher conditions and seasonal variation in food supply, hunting became more important to bridge the seasonal gaps, as well as the ability to store nonperishable items such as nuts, bulbs, and tubers for the winter when the edible plants withered in the autumn. All of these factors, along with clothing (and also perhaps fire), helped enable colonization of the less hospitable environment." clearly admits that such humans were well outside of their natural ecological niche which would provide the proper nutrition for our species, thus they were forced to consume highly foreign, non-natural "foods" just to survive. So, it is obvious that any claims as to the applicability of the Paleolithic diet to any understanding of the natural diet for our species are totally, and unavoidably, bogus. They are shams firmly based on lies and intentional distortions. They are merely other examples of how "curiosity killed the cat". See the movie: The Quest For Fire for a little insight into the perils created by abandoning our ecological niche.
If one can get a meatarian propagandist to actually admit that these incredibly recent, human flesh-eating practices are only a cultural artifact, then the ruse becomes: "Yes, it is not natural, but we 'adapted' or 'evolved' to eating animal flesh and products". This is another blatant, yet annoyingly popular, lie, and it can not be supported by current evolutionary theory. Where, indeed, are our claws, fangs, beaks, or talons?
Evolution happens because of small, infrequent, random mutations in the genetic material: most mutations are neutral and are never expressed, some very small number may be "beneficial" in that they allow better functioning in the environment, and some very small number may be deleterious, such as those that produce "genetic diseases". There must also be some "selective mechanism" to produce more survival success in those with the "beneficial" mutation, or it will not propagate throughout the species to produce a species-wide "adaptation". So, what are the "selective pressures" or "selective mechanism" that would cause the numerous and large-scale changes in dozens of separate biochemical pathways involved in human digestion, transport, and assimilation of a diet so radically different in chemistry as an alleged "adaptation" from plant chemistry to flesh chemistry? Note that dozens of biochemical pathways must change simultaneously in the same individual for such an "adaptation" to occur. There are none. Because a faulty diet does not kill its proponents outright BEFORE reproductive age, there is simply no way to "adapt" to a diet radically different in chemistry from the natural one for that species, even IF the dozens of required changes magically occurred in one individual. This is admitted in the BeyondVeg site: "The foods that humanity originally evolved to eat and those we now eat in modern civilization are in many cases significantly different--yet our basic underlying genetic inheritance remains basically the same as it was before, and has evolved only very slightly since then. Thus, many of the foods we now eat are discordant with our genetic inheritance."[W2]
Not surprisingly, all such claims as to the unsupported human 'evolution' from frugivores to omnivores conveniently do not mention the fact that neither the necessary sharp tools (teeth, claws), digestive biochemistry, fleetness of foot, nor animal-killing instincts have co-evolved with the alleged 'evolution' to omnivore. Why did the concomitant, and quite necessary, tools NOT co-evolve? People distorting evolutionary theory to make the evolutionary omnivore argument fall silent on those points.
In bizarre self-contradiction, BeyondVeg uses this evolutionary analysis to claim that modern grains and legumes are not a suitable food, with which I firmly agree, but it simultaneously, and perhaps intentionally, does not apply this understanding to the obvious fact that the human simply has not "evolved" to successfully consume animal flesh or other animal products. The epidemiological evidence that eating animal products causes all the currently popular "degenerative diseases" is conveniently overlooked in the presentation.[E1, E2, E3, E4] It gets even more amusing: "humans ... are in a transitional state from omnivory to obligate carnivory."[W3] This foolishly claims that humans are 'evolving' from frugivores, through cultural (not natural) omnivores to pure (obligate) carnivores, like the cat, dog, eagle, or alligator! This by a PhD, who most certainly does not kill and eat his/her animal prey raw and with his own natural physiological equipment; but, perhaps, has the initial appearances of claws and fangs, and is indeed on the cutting edge of 'evolution', such as to have such remarkable insight?
On the B-12 issue, the self-contradictions continue. "Cats can neither synthesize B-12 nor absorb it from their gut; consequently they have become wholly dependent upon animal flesh as their source for this essential nutrient."[ibid] Let's see, they can't absorb it from their gut, but eat flesh and then absorb it from their gut?
There is hope for the vegetarian/vegan, however: "Regarding possible B-12 synthesis in the small intestine above the ileum, the consensus of scientific literature indicates any amounts that may potentially be produced are not significant or reliable enough to serve as a dependable or sole source for most individuals.[ibid] MOST individuals? That means SOME individuals do produce and absorb their own B-12; could it be that the cause in the ones who can not is based on the fact that their intestines are ravaged by the toxic byproducts of putrefying meat, and that a healthy intestinal system in a healthy human is a reliable source of B-12? The practical solution to any concerns about B-12 is a simple and inexpensive supplement; which, given the precipitously declining quality of commercial produce, would be useful insurance anyway. The claim: "...demonstrate the human metabolic need for animal-based foods" ignores the fact that B-12 producing bacteria are abundant in the exogenous environment.[E5]
Interestingly, "In one study of vegans ... the [source of B-12] was due to eating unwashed vegetables that had been grown in gardens containing intentionally manured soils, from which the B-12 came. Ironically, the manure in this case was their own excrement, which as pointed out above harbors bacteria that produce B-12 in the human colon--where B-12 cannot be absorbed. Not unless, of course, it is reingested as in the unintentional coprophagy occurring in this instance, so that it can pass back through the small intestine again to the ileum where B-12 is actually absorbed."[ibid] Of course, it is unknown just how this study differentiated between the B-12 molecules coming from bacteria in the human colon and the B-12 coming from bacteria in the soil. It also ignores the fact, know by olfactory experience among vegetarians/vegans who are not eating huge excesses of protein, and totally unknown among meatarians who are eating huge excesses of indigestible proteins, that vegetarian/vegan feces is devoid of the common, malodorous, toxic amino compounds commonly found in meatarian feces: indole, skatole, putrescine, and cadaverine.
"In summary, the absence of the ability of humans to absorb bacterially produced B-12 in the colon, and the evidence that strictly behaving vegans will show negative TCII-carried B-12 balance even when total serum levels are in the normal range, is indicative of the long evolutionary history of animal-based foods in our diet."[ibid] Actually, it is more likely an indication of the rather recent deadly cultural practice of dousing commercial food with boundless amounts of toxic pesticides and herbicides which will kill the normal B-12-producing bacteria, and everything else, in the soil, coupled with the rather recent cultural sanitary hysteria which, also, will eliminate exogenous B-12 from food.
 McGrawHill Concise Encyclopedia of Science and Technology, 2nd ed., p. 323.http://www.ecologos.org/index.html