Food for Thought, or
Food for Propaganda?

Scientific American Feature Article December 2002 issue
Food for Thought: Dietary change was a driving force in human evolution
by William R. Leonard

WILLIAM R. LEONARD is a professor of anthropology at Northwestern University. He was born in Jamestown, N.Y., and received his Ph.D. in biological anthropology at the University of Michigan at Ann Arbor in 1987. The author of more than 80 research articles on nutrition and energetics among contemporary and prehistoric populations, Leonard has studied indigenous agricultural groups in Ecuador, Bolivia and Peru and traditional herding populations in central and southern Siberia.

     WL: We humans are strange primates.
     True, and the fiction they create disguised as "science" to support their own personal cultural conditioning and superstitions, which they refuse to examine logically, is even stranger.

     WL: We walk on two legs, carry around enormous brains and have colonized every corner of the globe.
      We also have, by the continuing misuse of those "enormous brains", brought to extinction tens of thousands of other species of Life, polluted ourselves and every corner of the planet, changed the weather on this planet, have been at constant war with our own species throughout our history, and are currently carrying on an unprecedented campaign of global ecocide.

     WL: Anthropologists and biologists have long sought to understand how our lineage came to differ so profoundly from the primate norm in these ways, and over the years all manner of hypotheses aimed at explaining each of these oddities have been put forth.
      Simple: culture.  The other species are driven by instincts, thus can function only in harmony with Nature, not destroy it and themselves through misuse of intellect as humans do as a result of cultural conditioning.  Some of the primates, such as the chimp, are starting to develop culture as shown by their limited flesh-eating.

     WL: But a growing body of evidence indicates that these miscellaneous quirks of humanity in fact have a common thread: they are largely the result of natural selection acting to maximize dietary quality and foraging efficiency.
      Natural selection made our species into the self- and omni-destructive plague that is currently destroying our planet?  This is, indeed, a perverted view of evolution.   "Quirks" of behavior are not the slightest bit related to evolution, which occurs in the physical body, only.  "Quirks" of behavior exist only in the domain of culture/consciousness, which is totally independent from, and different than, genetic processes.

     WL: Changes in food availability over time, it seems, strongly influenced our hominid ancestors. Thus, in an evolutionary sense, we are very much what we ate.
      Here, the false and long-abandoned 18th Century Lamarckian view of evolution, that personal behavior in one generation influences the physical evolution of the species in the next, is invoked.  If were really "are what we ate", then the human species would show some signs of "adapting" to a flesh-oriented diet; however, we have developed no physiological or biochemical tools to do so successfully.  Further, the current epidemiology of degenerative diseases proves otherwise, also.

     WL: Accordingly, what we eat is yet another way in which we differ from our primate kin.
      Much to our own detriment, as epidemiology shows.

     WL: Contemporary human populations the world over have diets richer in calories and nutrients than those of our cousins, the great apes.
      Thus, humans are the only ape species to suffer rampant acute and "degenerative diseases".

     WL: Scientific interest in the evolution of human nutritional requirements has a long history.
      Yet, evolutionary theory provides no known mechanism whereby any species can adapt to a diet different that the one prescribed by its own biochemistry.  The "nutritional requirements" of the human ape has not changed over time, and that is the reason cultural diets inevitably produce disease profiles characteristic of their local chemistry.

     WL: But relevant investigations started gaining momentum after 1985, when S. Boyd Eaton and Melvin J. Konner of Emory University published a seminal paper in the New England Journal of Medicine entitled "Paleolithic Nutrition." They argued that the prevalence in modern societies of many chronic diseases--obesity, hypertension, coronary heart disease and diabetes, among them--is the consequence of a mismatch between modern dietary patterns and the type of diet that our species evolved to eat as prehistoric hunter-gatherers.
      The glaring error in the whole Paleolithic Diet mythology, conveniently and uniformly overlooked by its proponents, is that there is no way our species could have "adapted" to it, as opposed to our original tropical frugivorous diet.  The claimed successes of adopting a Paleo diet is an effect due only to the fact that it is somewhat closer, chemically, to the original than the modern, processed, low-fiber flesh/dairy/grain/junk food cultural diets.  Thus, reducing some of the modern dietary perversions will produce some improvement; however, reducing them further by adopting a frugivorous ape diet will obviously produce better results, and this is born out in practice.  The Paleo diet propagandists ignore the fact that there is no mechanism espoused in modern evolutionary theory that will allow any species to "adapt" to a diet radically different, chemically, from its natural one.  Note that we do not see any other species changing its diet radically over time; only the human does this due to culture and choosing to live in an environment not its natural ecological niche.

     WL: Since then, however, understanding of the evolution of human nutritional needs has advanced considerably--
      Is there any evidence that any other species demonstrated any "evolution of nutritional needs"?  Do we see the diet of any other species changing over time?

     WL: ... thanks in large part to new comparative analyses of traditionally living human populations and other primates--and a more nuanced picture has emerged.
     Major error: "traditionally living human populations" also eat unnatural, culturally-driven flesh-including diets that necessitate tools and fire.  This "Noble Savage" paradigm falsely assumes that such tribes are eating the natural one for our species, and that is simply not true if tools and fire are necessary to secure or consume any element in that diet.

     WL: We now know that humans have evolved not to subsist on a single, Paleolithic diet but to be flexible eaters, an insight that has important implications for the current debate over what people today should eat in order to be healthy.
      Nonsense: we simply do not see any other species "evolving" to eat as "flexible eaters" since animals eat as a function of their instincts which obviously do not change over time or as a function of cultural whim (except in those species "advanced" enough to be exhibiting cultural behavior).

     WL: To appreciate the role of diet in human evolution, ...
     We should look at current evolutionary theory and discover that there are no mechanisms elucidated by which any species' inherent biochemistry changes as a function of its dietary input.  Humans do not have this magical ability, either.

     WL: Thus, by looking at the way animals go about obtaining and then allocating food energy, we can better discern how natural selection produces evolutionary change.
      One does not find this in contemporary evolutionary theory.  This implies that behavior influences evolution, the long-abandoned Lamarckian theory.

     WL: Chimps, gorillas and orangutans evolved in and continue to occupy dense forests where only a mile or so of trekking over the course of the day is all that is needed to find enough to eat. Much of early hominid evolution, on the other hand, took place in more open woodland and grassland, where sustenance is harder to come by.
      So, the human apparently abandoned its natural ecological niche, which resulted also in its abandoning its natural diet.

     WL: Indeed, modern human hunter-gatherers living in these environments, who provide us with the best available model of early human subsistence patterns, often travel six to eight miles daily in search of food.
      Here is another fundamental error.  Once our species abandoned its proper ecological niche and the plants therein, and thus also abandoned its natural, biologically-correct diet, any diets chosen in a different ecosystem can NOT be used as any valid indication of human nutritional needs.  That is, our inherent digestive and assimilative biochemistry did NOT change to accommodate any new, cultural diet; there is nothing in current evolutionary theory that supports this even as a possibility, and certainly not as a fact.  By conveniently ignoring this fundamental fact, the Paleo Diet propagandists blithely, dishonestly, and without the slightest bit of credible support, claim it did.

     WL: ... bipedalism can be viewed as one of the first strategies in human nutritional evolution ...
      Strategy implies conscious decision; evolution occurs mechanically, without the slightest bit of participation of the intellect of the individual or the evolving gene pool.

     WL: Across all primates, species with bigger brains dine on richer foods, and humans are the extreme example of this correlation, boasting the largest relative brain size and the choicest diet [see "Diet and Primate Evolution," by Katharine Milton; Scientific American, August 1993].
     This allegedly "choicest diet" of cultural humans has led directly to all the currently-popular "degenerative diseases" not seen in the wild.
     See my critique of Milton's bizarre concepts and illogic.
     Some real data, shown in this graph, however, clearly indicate that largest primates eat NO "richer foods", i.e. animal flesh, but conversely the smallest primates consume the most.  Note that the facts refute ML's propagandistic claims.


     WL: According to recent analyses by Loren Cordain of Colorado State University, contemporary hunter-gatherers derive, on average, 40 to 60 percent of their dietary energy from animal foods (meat, milk and other products).
     Cultural diets, hunter-gatherer or couch potato, are not the slightest bit useful for developing an understanding of the optimally-healthy human diet.  Bringing in factual, but totally irrelevant, data to create the illusion of credibility is a common, reprehensible tactic among propagandists.

     WL: Modern chimps, in comparison, obtain only 5 to 7 percent of their calories from these comestibles.
     WL seems to also accept the arithmetically-absurd concept of "% of calories from xxx".

     WL: Animal foods are far denser in calories and nutrients than most plant foods.
     True, and that is a reason that eating them leads to obesity, heart disease, cancer, and toxin-producing putrefactive bacteria in the colon.

     WL: For example, 3.5 ounces of meat provides upward of 200 kilocalories. But the same amount of fruit provides only 50 to 100 kilocalories. And a comparable serving of foliage yields just 10 to 20 kilocalories.
      So what??  With 65% of Americans being overweight, obese, or morbidly obese what is the point of "evaluating" the desirability or appropriateness of "foods" based on calorie content alone?  Would he recommend coal or petroleum based on their calorie content alone?  There is an unstated and quite erroneous assumption in WL's irrational pro-meat propaganda, and that is that all ingested dietary calories are efficiently and totally converted to usable calories, and that is simply not true.  The body muscles and brain uses glucose, blood sugar, as a source of energy, and it is a lot easier to convert fruit sugars, and less easy to convert starches, to glucose than animal protein or fat.
     Nuts have a calorie density comparable to meat, and there is NO cholesterol, cooking-induced carcinogens, artery-clogging animal fats, denatured protein, farm-chemical residues, bacterial contamination, antibiotics, or other hazards inherent in meat consumption.

     WL: It stands to reason, then, that for early Homo, acquiring more gray matter meant seeking out more of the energy-dense fare.
     No, there is no "reason" here; this "meat-eating caused brain growth in humans" theory is commonly touted in Paleo propaganda, yet strangely, obligate carnivores did NOT produce large brains as a result of their only-flesh-consumption, and conversely the large brains of the elephant and gorilla do quite well on plant-based diets.  Several misconceptions about brain size are discussed here.

     WL: Fossils, too, indicate that improvements to dietary quality accompanied evolutionary brain growth.
     There is no way to "improve dietary quality", since the proper/optimum diet for any species is fixed at the genetic level and manifested by each individual species' inherent physiology, biochemistry, and instincts.  There is no way to "improve" on the original design by cultural diets, and the profusion of cultural diet-caused degenerative diseases is proof of that.  I am always amused by such pseudoscientific claims regarding the great wonders conferred to our species by flesh-eating, when the proponents of such claims can not explain just why the human did NOT evolve the sharp, pointy tools seen among all natural flesh-eaters, and especially why we did NOT evolve instincts to capture, kill, and eat flesh raw.  In fact, there is a strong anti-instinct to do so, and no proponent of these nonsensical theories will test their beliefs by killing and eating raw any small animal, using only their natural equipment.

     WL: (This is not to say that australopithecines never ate meat. They almost certainly did on occasion, just as chimps do today.)
      Strangely, people who bring this trivial fact up never indicate that this is strictly a cultural practice among chimps, and certainly not a nutritional imperative.  Shouldn't anthro-apologists be able to distinguish between culture and Nature?

     WL: As to what prompted Homo's initial shift toward the higher-quality diet necessary for brain growth
     There is no evidence that any "higher-quality" diet exists; the proper diet for any species is dictated at the genetic level.  Similarly, there is no evidence that different diets are necessary for small or large brains.

     WL: The continued desiccation of the African landscape limited the amount and variety of edible plant foods available to hominids.
     True, but irrelevant to any discussion of the natural/optimum diet for our species as these groups had left their proper ecological niche and the plant communities therein.

     WL: As it turns out, the spread of grasslands also led to an increase in the relative abundance of grazing mammals such as antelope and gazelle, creating opportunities for hominids capable of exploiting them. H. erectus did just that, developing the first hunting-and-gathering economy in which game animals became a significant part of the diet and resources were shared among members of the foraging groups. Signs of this behavioral revolution are visible in the archaeological record, which shows an increase in animal bones at hominid sites during this period, along with evidence that the beasts were butchered using stone tools.
     True, but irrelevant, since the use of tools/fire is absolutely and unquestioningly not necessary with our biologically-corrent diet; conversely, their use proves that the items for which they are necessary are NOT part of our natural diet.  It is insightful that anthro-apologists conveniently obfuscate or ignore the profound differences between Nature and culture to support their hollow theories.  Will the evidence of pesticide pollution in our corpses some 10,000 years from now convince those future anthro-apologists that we somehow "adapted" to pesticides?

     WL: ... the addition of modest amounts of animal foods to the menu ... would have significantly increased the quality and stability of hominid diets.
      No evidence is presented that links animal foods and "quality" of diets.  In fact, there is none; however, there is abundant and convincing data that all the currently-popular "degenerative diseases" are linked with the consumption of "animal foods".  This false link is simply assumed as a result of WL's cultural programming and superstition; clearly, he has not any personal experience with plant-based diets, or such foolishness would not be presented as fact.  Insightfully, people who tout human flesh-oriented diets, or disparage human plant-based diets, generally have not had any personal experience with the latter.

     WL: The impetus behind this newfound wanderlust again appears to be food. What an animal eats dictates to a large extent how much territory it needs to survive. Carnivorous animals generally require far bigger home ranges than do herbivores of comparable size because they have fewer total calories available to them per unit area.
      But, wait.  Weren't we told that a flesh-oriented diet was "better" since it was more calorie-dense and thus necessitated less locomotion?  Carnivores do not have "home ranges"; they follow herbivore herds, or hang out at watering holes, and have an incredibly-populous food sources available at all times.

     WL: Large-bodied and increasingly dependent on animal foods, H. erectus most likely needed much more turf than the smaller, more vegetarian australopithecines did. Using data on contemporary primates and human hunter-gatherers as a guide, ... I have estimated that the larger body size of H. erectus, combined with a moderate increase in meat consumption, would have necessitated an eightfold to 10-fold increase in home range size compared with that of the late australopithecines.
      Weren't we told above that a "better", more calorie-dense diet necessitated LESS locomotion to obtain it?

     WL: -- enough, in fact, to account for the abrupt expansion of the species out of Africa. Exactly how far beyond the continent that shift would have taken H. erectus remains unclear, but migrating animal herds may have helped lead it to these distant lands.
     And, moving out of our natural ecological niche also was responsible for the "addiction" our species developed to tools and fire, with the logical diminution of health resulting from using such.

     WL: As humans moved into more northern latitudes, they encountered new dietary challenges. The Neandertals, who lived during the last ice ages of Europe, were among the first humans to inhabit arctic environments, and they almost certainly would have needed ample calories to endure under those circumstances. Hints at what their energy requirements might have been come from data on traditional human populations that live in northern settings today. The Siberian reindeer-herding populations known as the Evenki, which I have studied with Peter Katzmarzyk of Queen's University in Ontario and Victoria A. Galloway of the University of Toronto, and the Inuit (Eskimo) populations of the Canadian Arctic have resting metabolic rates that are about 15 percent higher than those of people of similar size living in temperate environments. The energetically expensive activities associated with living in a northern climate ratchet their caloric cost of living up further still. Indeed, whereas a 160-pound American male with a typical urban way of life requires about 2,600 kilocalories a day, a diminutive, 125-pound Evenki man needs more than 3,000 kilocalories a day to sustain himself. Using these modern northern populations as benchmarks, Mark Sorensen of Northwestern University and I have estimated that Neandertals most likely would have required as many as 4,000 kilocalories a day to survive. That they were able to meet these demands for as long as they did speaks to their skills as foragers.
      Interesting as these comments are, they completely ignore the negative health consequences of living is such unnatural environments and consuming the unnatural diets; that is, why do these types of "analysis" always ignore the poor health and shortened life spans of these tribes?

Modern Quandaries

     WL: Just as pressures to improve dietary quality influenced early human evolution, so, too, have these factors played a crucial role in the more recent increases in population size.
      Where do we see these supposed "pressures to improve dietary quality" elsewhere in Nature?  Nowhere. They did not exist.

     WL: Innovations such as cooking, agriculture and even aspects of modern food technology can all be considered tactics for boosting the quality of the human diet.
      There is no rational argument that suggests that cooking and/or modern food technology "boosts" the "quality of the human diet"; in fact, the opposite is true.

     WL: Cooking, for one, augmented the energy available in wild plant foods.
      The cooking of starchy plants, such as roots and tubers, increases the availability of starch for digestion because the cell walls are broken, thus cell contents are more readily available to digestive enzymes.  However, the creation of carcinogens, mutagens, teratogens, Maillard reaction chemicals, cross-linked protein-sugar complexes, various toxic and foreign species of chemicals, and the reduction of the nutritional efficacy of many nutrients by cooking are all conveniently ignored.

     WL: With the advent of agriculture, humans began to manipulate marginal plant species to increase their productivity, digestibility and nutritional content-- essentially making plants more like animal foods. This kind of tinkering continues today, with genetic modification of crop species to make "better" fruits, vegetables and grains. Similarly, the development of liquid nutritional supplements and meal replacement bars is a continuation of the trend that our ancient ancestors started: gaining as much nutritional return from our food in as little volume and with as little physical effort as possible.
      Conveniently, the ongoing reduction in nutritional quality of commercial products over time as a result of this continuing "progress" and the coming horrors related to genetically-modified organisms being released into the wild are ignored.

     WL: Overall, that strategy has evidently worked: humans are here today and in record numbers to boot.
      When did quantity relate to quality?  The health of people who are victims to this "tinkering" is rapidly decreasing, as seen in the ever-increasing disease statistics.

     WL: But perhaps the strongest testament to the importance of energy- and nutrient-rich foods in human evolution lies in the observation that so many health concerns facing societies around the globe stem from deviations from the energy dynamic that our ancestors established.
      Here, the false concept that our ancestors' misguided nutritional perversities somehow affected our genes in a way such as to require our continuing their mistakes is propagated again.

     WL: For children in rural populations of the developing world, low-quality diets lead to poor physical growth and high rates of mortality during early life. In these cases, the foods fed to youngsters during and after weaning are often not sufficiently dense in energy and nutrients to meet the high nutritional needs associated with this period of rapid growth and development. Although these children are typically similar in length and weight to their U.S. counterparts at birth, they are much shorter and lighter by the age of three, often resembling the smallest 2 to 3 percent of American children of the same age and sex.
      Could the growth hormones, both natural and artificial, in animal products be responsible for this excessive growth?  When did bigger mean better?  Especially with the global epidemic of obesity rapidly following the introduction of "modern civilized foods"?

     WL: In the industrial world, we are facing the opposite problem: rates of childhood and adult obesity are rising because the energy-rich foods we crave--notably those packed with fat and sugar--...
      Hmm, animal and junk "foods" ; exactly what was touted as beneficial "tinkering".

     WL: Obesity has also appeared in parts of the developing world where it was virtually unknown less than a generation ago.
      As tradition diets, somewhat closer to our nutritional needs, are abandoned in favor of "tinkered foods", including more animal foods.

     WL: We are victims of our own evolutionary success, ...
      What an incredibly stupid thing to say.  It is "evolution's" fault for the current state of degenerate health existing only in the human species.

     WL: The magnitude of this imbalance becomes clear when we look at traditionally living human populations. Studies of the Evenki reindeer herders that I have conducted in collaboration with Michael Crawford of the University of Kansas and Ludmila Osipova of the Russian Academy of Sciences in Novosibirsk indicate that the Evenki derive almost half their daily calories from meat, more than 2.5 times the amount consumed by the average American. Yet when we compare Evenki men with their U.S. peers, they are 20 percent leaner and have cholesterol levels that are 30 percent lower.
      The dietary practices of people living so far from our natural ecological niche has no relevance to our optimally-healthy diet.  What is the life span and health profile of these people?  This important data is always ignored in "the noble savage" paradigm.

     WL: These differences partly reflect the compositions of the diets. Although the Evenki diet is high in meat, it is relatively low in fat (about 20 percent of their dietary energy comes from fat, compared with 35 percent in the average U.S. diet), because free-ranging animals such as reindeer have less body fat than cattle and other feedlot animals do. The composition of the fat is also different in free-ranging animals, tending to be lower in saturated fats and higher in the polyunsaturated fatty acids that protect against heart disease. More important, however, the Evenki way of life necessitates a much higher level of energy expenditure.
     So, he admits that such "apple and orange" comparisons are useless?

     Again, we see that anthro-apologists have abandoned real science, facts, and logic in their fanciful creative writing efforts.




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