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(Comparative Anatomy and Physiology Brought Up to Date--continued, Part 3B)

Examining the rationalizations and denials
of the fossil record evidence of human diet

As one might expect, the preceding information has been met with denial, crank science, and rationalizations from some in the raw vegan (and general veg*n) community. Some of these rationalizations and denials are as follows, with relevant comments.

CLAIM: What about the time before humans? What about Australopithecus? Aren't there tooth-wear studies that prove Australopithecus was a fruitarian?

REPLY: If you go back far enough, you are dealing with a NON-HUMAN primate. Australopithecus was a bipedal hominid in the line that led to humans, and was the last hominid prior to the evolution of Homo habilis, the first human in the genus Homo, but Australopithecus was itself still pre-human. If you go back somewhat further, you are dealing with apes that were primarily frugivorous, but as we will see below in discussing Australopithecus further, their diet would have included foods that were tougher than what we would generally call fruits today. Prior to these apes, if we go all the way back to the first primates 65 to 70 million years ago, from which all other primates evolved, then the diet was primarily insects.

The important point regarding evolution is, as noted above, that the human diet has included meat since the inception of the human genus (Homo), and we have adapted to such a diet. If the diet of ancient frugivorous non-human primates is somehow supposed to be "very relevant" (more relevant, anyway, than diets of actual members of the genus Homo), then we are basically engaging in an absurd game of "moving the goalposts." If that's legitimate, then we might also say that the diet of the ancient insectivorous primates could be just as relevant.

Outdated toothwear studies often cited. As for Australopithecus, the highly publicized tooth-wear studies cited in fruitarian/vegetarian lore are dated. (See related discussion in Part 1 of the Paleolithic Diet vs. Vegetarianism series.) Newer isotope studies of Australopithecus fossils indicate an omnivorous diet: Sillen [1992] analyzed the strontium/calcium (Sr/Ca) ratios in Australopithecus fossils, and concluded (p. 495):

When specimens of the fossil Australopithecus robustus were examined, Sr/Ca values were inconsistent with that of a root, rhizome or seed-eating herbivore, suggesting that the diet of this species was more diverse than previously believed, and almost certainly included the consumption of animal foods.

The results of Sillen [1992] were confirmed in a separate study, using stable carbon isotopic analysis; see Lee-Thorp et al. [1994] for details. Also see Sillen et al. [1995] for a followup to Sillen [1992].

Ancient fruits of different character than today's. A further note on Australopithecus: The fruits in its diet were not like today's modern sweet hybrid fruits (such as one buys in a supermarket or produce stand). Instead, they included some very tough plant foods. Peters and Maguire [1981] analyzed the wild plant foods available in the Makapansgat (South Africa) area, and determined the structural strength of the foods available. They note (p. 565):

Moreover, the most important potential plant food staples include very tough dry berries, beans and nuts, which require an average of 50-250 kg of compressive force to crack and crush them.

Peters and Maguire concluded that even the strong (stronger than modern human) jaws of Australopithecus africanus were not strong enough to prepare all the tough plant foods, and simple stone tools would be necessary for survival in such an environment. (Needless to say, the fruits eaten by Australopithecus were markedly different from the diets advocated by modern promoters of fruitarianism--modern fruitarian diets emphasizing juicy, sweet fruits.)

CLAIM: Our prehistoric ancestors could not eat meat prior to the advent of tools. (Often stated very emotionally as: Well, what about the time BEFORE tools!?)

REPLY: Chimpanzees kill and eat small animals without tools. The method used is flailing; see Butynski [1981, table 2, p. 425] for details; also van Lawick-Goodall [1971, p. 283] for illustration. If chimpanzees can kill small prey without tools via flailing, humans are certainly capable of the same.

Naked apes without tools? Some fruitarian advocates promote the crank science/science-fiction claim that humans are merely "naked apes, without tools," and that the human diet should be limited to foods that can be obtained when one is nude, without tools. This bizarre fantasy is interpreted to mean that humans should limit their diets to soft fruits, leaves, and occasional seeds or nuts. However, even as stated, the fantasy actually implies the inclusion of a wide range of potential animal foods in the "natural" human diet. See the article, Selected Myths of Raw Foods, for further discussion of this, which includes a list of animal foods that meet the stated collection requirements.

Note: A recent research report that capuchin monkeys are capable of making and using stone tools (see Westergaard and Suomi [1994]) demonstrates how utterly ridiculous the "naked ape without tools" myth is. One might regard such a myth as bizarre crank science; unfortunately a few fruitarian extremists promote the myth--often in a hostile manner.

However, the most relevant point here is that humans have used tools since the inception of the human genus, so the question, "What about the time before tools?" is actually the question, "What about the time before the human genus existed?" This indicates the question is of limited relevance.

CLAIM: Eating meat is a perversion and UNnatural, but it does not affect reproduction. Hence, eating meat does not affect evolutionary selection. Thus, we are NOT adapted to meat-eating despite the dreadful "cultural" habit of eating meat for literally millions of years! (This argument is often stated in a highly emotional manner.)

REPLY: The above attitude is common in the raw veg*n movement. Such an attitude also reflects misunderstanding and ignorance of how evolution works. Even if eating meat is "cultural" rather than a required survival tactic (the evidence of hunter-gatherer tribes suggests it is necessary for survival when living in the wild), if meat-eating is universal, then meat-eating is, in effect (or by default), a part of the environment. Once meat-eating becomes a part of the long-term environment, then evolutionary selective pressure will favor genes that are best adapted to that environment. In the long term, genetic adaptation to such a diet, by evolution, is the inevitable result.

To illustrate this point, let us consider yet another crank-science fantasy promoted by certain fruitarian advocates: that of a pure fruitarian human for whom protein foods are "toxic," meaning that protein, above quite low levels (far below the levels accepted as necessary even by more mainstream vegan advocates), is believed harmful because it causes the production of "toxic" metabolic by-products. (Those not familiar with fruitarian lore may find such claims to resemble science fiction; unfortunately, such nonsense is actively promoted in some quarters.)

Could a fruitarian human have survived and evolved in an ancient environment favoring meat-eating? Assume a genetic mutation occurs and a human is born into a meat-eating prehistoric group, but this human is--by pure chance--adapted to be a pure frugivore (fruit only), and protein is "toxic" (as described above) to that person. Clearly, such a person will not survive, long-term, in the meat-eating environment (the individual would eventually die from the toxic effects of the by-products of protein digestion) or would live a short, unhealthy life and be less likely to reproduce (hence the genes fail to survive long-term given that they will be out-competed reproductively).

In sharp contrast to the preceding, any genetic mutations that enhance survival in the environment of meat-eating will exist in an environment where they can and will thrive--and will, over evolutionary time, out-compete those adaptations that do not enhance survival. This illustrates how interaction between behavior (culture) and the environment creates selection pressure that favors the universally prevalent diet (meat-eating) and disfavors a rare, narrow diet (e.g., fruit only) that is outside the range of the environmental support system. (Note: the remarks of Mann [1981] above are relevant here--I am not suggesting that the evolutionary human diet was 100% meat. Instead, it was a mix of animal and plant foods, varying according to location and seasonal availability of foods. The point is that meat was a significant part of the diet, hence "natural" in the most rigorous sense.)

What does "survival of the fittest" actually mean? The claim that humans have not adapted to meat in ~2.5 million years of consumption rests on a misunderstanding of the principle of survival of the fittest. The idea that eating meat may not at first glance appear to (favorably) affect the reproduction of individuals comes from a misapplication and limited examination of the principle of survival of the fittest--that is, it considers the question on an individual, short-term basis only.

However, survival of the fittest is really a broad-based, long-term (multi-generational) proposition. Those traits--mutations and adaptations--that ensure or promote survival over time and over multiple generations are the traits that will be propagated the most successfully and survive; this is the real meaning of survival of the fittest. Further, evolutionary selective pressure is driven by survival--an amoral principle--and not by such moral considerations as whether eating meat is moral or immoral, "good" or "bad," whether it violates so-called animal rights, and so on.


(Diet, Evolution, and Culture / Fruitarian Reaction to Evolution)

Return to beginning of article



GO TO PART 1 - Brief Overview: What is the Relevance of Comparative Anatomical and Physiological "Proofs"?

GO TO PART 2 - Looking at Ape Diets: Myths, Realities, and Rationalizations

GO TO PART 3 - The Fossil-Record Evidence about Human Diet

GO TO PART 4 - Intelligence, Evolution of the Human Brain, and Diet

GO TO PART 5 - Limitations on Comparative Dietary Proofs

GO TO PART 6 - What Comparative Anatomy Does and Doesn't Tell Us about Human Diet

GO TO PART 7 - Insights about Human Nutrition & Digestion from Comparative Physiology

GO TO PART 8 - Further Issues in the Debate over Omnivorous vs. Vegetarian Diets

GO TO PART 9 - Conclusions: The End, or The Beginning of a New Approach to Your Diet?

Back to Research-Based Appraisals of Alternative Diet Lore

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