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(Comparative Anatomy and Physiology Brought Up to Date--continued, Part 8F)

Instinct vs. Intelligence in Diet:
Where is the Line?

This section will briefly address the interactions between instinct and intelligence; and then a long list of claims (about instinct) made by raw-vegan/fruitarian extremists will be discussed.

Introduction: The difficulty of distinguishing between instinct and intelligence

One claim often made by those advocating comparative proofs of vegetarianism is that eating plant foods is instinctive, while eating animal foods is non-instinctive or unnatural. Accordingly, the question of whether particular actions are due to instinct or intelligence is controversial and a source of major disagreement. The problem lies in "confounding"--that is, how to separate instinct from intelligence in the arguably "unnatural" modern world we live in. There appear to be no hard answers to the questions here, although many raw/veg*n advocates claim otherwise.

Individual intelligence can override instinctive restraints. A good introduction to the topic is provided by Itzkhoff [1985, p. 171]:

All our difficulties, as well as all our possibilities have come about because the sapient brain overrode the last restraints, indeed the directiveness, that instinct gives to animals. In the animal world, intelligence is guided by instinct to achieve clear-cut survival needs...

Man, the generalized intelligent ape, has a brain that establishes the rules of the game, almost irrespective of the individual's bodily or even grossly survivalistic needs... What remains to man after these basic conservational restraints of instinct are extinguished is a super-intelligence that filters all major categories of human behavior through the cortex. He is a thinking animal with a complex brain, a supremely energized mammalian brain that must now control, direct, guide his behavior. The old passions, energies, and drives no longer have built-in censors.

A number of raw/veg*n advocates openly criticize intelligence because it allows you to override your instinct, which the advocates claim (with virtually no credible proof or logic to support them) is that of a veg*n animal. The argument is that intelligence allows you to eat the "wrong" foods (where "wrong" is usually equivalent to whatever the dietary advocate dislikes), and these "wrong" food choices often get institutionalized into culture. Some of the more extreme raw dietary advocates (fruitarians, mostly) bitterly and hatefully denounce cultural eating patterns, and culture in general, because of this.

Eating Animal Foods, Part 1:
Instinct or intelligence?

The major question to address here is whether eating meat or animal foods is instinctive or not. A number of raw/veg*n advocates allege that everyone is repulsed by the act of killing another animal and eating its flesh. It should be noted that no real proof is ever offered to back up such claims; what proof--other than the advocate's personal feelings--is there on this subject?

Let's consider the claims that people are "naturally repulsed" by the act of killing and eating other animals. Such claims are clearly contradicted by the following:

So, next time a veg*n dietary advocate claims that our instincts prevent humans from killing and eating animals, ask them for credible proof of their claim(s). The advocate may simply be projecting his/her personal moral and emotional preferences onto others.

However irritating--or enjoyable--the preceding analysis may be to you, it still does not directly answer the question of whether eating meat is instinctive or not, of course. Obviously, if eating meat (or veggies) is absolutely necessary for survival (survival is certainly an instinct), then it is, by definition, instinctive. However, in today's modern society, with a huge variety of foods available, how often is it absolutely necessary to eat any one food or food type (as substitutes are usually available)?

Eating Animal Foods, Part 2:
An evolutionary view

Another approach to answering the question is to consider our evolutionary history, and to note that, since the very inception of the human (Homo) genus, ~2.5 million years ago, the human diet has included meat, and our metabolic and morphological makeup appear to reflect varying degrees of adaptation to animal foods in the diet. Thus one can argue that eating animal foods is instinctive, because it is natural behavior--behavior that we have followed long enough so that evolutionary adaptation has taken place.

The association of increasing brain size with animal food consumption. For many readers, the preceding paragraph is a convincing argument. However, other readers will quickly ask: What about the confounding effects of intelligence? Here the expensive tissue hypothesis of Aiello and Wheeler [1995], and related research, is relevant. Recall that the major point of the expensive tissue hypothesis is that the human brain increased in size (and our intelligence increased) via brain evolution fueled by a switch to a diet that included very significantly increased amounts of meat, and which allowed our gut (digestive system) to shrink thereby freeing metabolic energy (to support the increase in brain size). This hypothesis, and the related research discussed in section 4 herein, suggest that the consumption of meat and the evolution of intelligence are closely interrelated.

To summarize, the evidence of evolution is as follows.

Given the above information, the obvious answer to the question, "Is meat-eating instinctive or driven by intelligence?" is that both apply. That is, one can argue that eating (wild) animal products is both instinctive and intelligent, for humans, from the evolutionary point of view.

Individual intelligence makes the final decision. On the other hand, at the individual level, intelligence may motivate some people to be raw/veg*ns, and to avoid animal products. That is an example of the power of human intelligence, acting at the individual or personal level.

Eating Animal Foods, Part 3:
Morality and naturalism

It is appropriate to remind readers of some important points here.


(Examining Fruitarian Claims about Instinct in Food Selection)

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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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