A poster session from the Williamsburg-ICAES conference. Interesting points include that primate food consumption that is 95% plant and 5% animal is still higher in protein and lower in carbohydrate than modern man. This article shows how the advent of agriculture humans have become the only primates to consume grains. Then this article discusses the disease consequences.

Evolution, Diet and Health

S. Boyd Eaton, MD

and

Stanley B. Eaton III

Departments of Anthropology and Radiology, Emory University,

Atlanta, Georgia USA



The nutritional requirements of contemporary humans represent the end-result of dietary interactions between our ancestral species and their environments extending back to the origins of life on earth. Primates of modern aspect are thought to have emerged about 50 million years ago and appreciating the basic range of primate nutritional patterns over this lengthy evolutionary period is critically important because only when the original simian baseline is characterized can subsequent dietary modifications within the hominid lineage be fully appraised. These nutritional changes have had significant evolutionary impact in the past and they now affect the health of contemporary human populations. The nature of these interactions can best be understood when the dietary alterations are measured against a fundamental primate benchmark.



The Primate Baseline

With regard to diet what students of human evolution and advocates of evolutionary medicine need most from paleoprimatologists is an estimate of the nutritional pattern likely to have characterized the last common ancestor of apes and humans, a hypothetical species thought to have existed in Africa between seven and five million years ago.

If members of this elusive taxon were like current chimpanzees and bonobos, plant foods such as fruits, leaves, gums, and stalks probably comprised at least 95% of their dietary intake with insects, eggs, and small animals making up the remainder (Milton, 1993; Tutin & Fernandez, 1993). The general nutritional parameters of an eating pattern along these lines can be estimated with modest confidence, although certainly not with mathematical exactitude. Protein would have contributed a greater proportion of total energy than it does for most contemporary humans, but with much more from vegetable sources than from animal. (Popovich, 1997) Simple carbohydrate intake would have been strikingly below that now common, and, somewhat counterintuitively, such diets would have provided only moderate levels of starch and other complex carbohydrates so that the total carbohydrate contribution to dietary energy would have been less, not more, than is typical in contemporary affluent nations. Dietary fiber would have exceeded current levels by an order of magnitude: 200 grams vs. 20 grams a day (Milton, 1993): for some ancestral hominoids, colonic fiber fermentation may have provided over 50% of total dietary energy. (Popovich, 1997) Daily intake of vitamins and minerals is likely to have been considerably greater than at present with the likely exception of iodine, consumption of which would have varied with geographic location according to oceanic proximity, volcanic activity, prevailing winds and rainfall. As it is for all other free-living terrestrial mammals, sodium intake would have been only a fraction of that currently common and would have been substantially less than that of potassium. (Denton, 1995) Availability of phytochemicals, like that of vitamins and most minerals would, in all likelihood, have been substantially greater than for Americans and other Westerners.

Total fat intake, especially of serum-cholesterol-raising saturated and trans fatty acids, must have been greatly below current American and European levels; cholesterol intake would have been minimal. Within the polyunsaturated fatty acid [PUFA] category, partition between the omega 6 and omega 3 (w-6 and w-3) families would have been reasonably equal or skewed slightly towards the w-3s. Polyunsaturated fatty acids from plant sources are predominantly, if not exclusively, 18-carbon or less in chain length; linoleic acid (LA, C18:2, w-6) and a-linolenic acid (ALA, C18:3, w-3) are typical. Accordingly, dietary intake of the longer chain C20 and C22 PUFAs such as arachidonic acid (AA, C20:4, w-6) and docosahexaenoic acid (DHA, C22:6, w-3) would have been low. (Eaton, 1998)



Scavenging, Hunting and Brain Expansion

Paleodental evidence suggests that after the divergence of early hominids from the hominoid ancestral line, a gradual increase in consumption of harder and/or more abrasive foods occurred - most likely nuts and seeds. This change probably increased intake of vegetable fat (mostly non-serum-cholesterol raising in nature) and would, perhaps, have facilitated overall access to food energy, but probably had little other nutritional effect. About 2.5 million years ago, however, there is evidence that animal foods began to occupy an increasingly prominent place in our ancestor’s subsistence. Decreased molar size, less mandibular and cranial robusticity, and alterations in incisor shape all suggest greater emphasis on foods requiring less grinding and more tearing, such as meat.

An increasing proportion of meat in the diet would obviously have provided more animal protein , a factor perhaps related to the stature increase which appears to have accompanied the transition from Australopithecines through Homo habilis to H. erectus, (McHenry, 1992) but greater availability of animal fat was probably a more important dietary alteration . Even crude Oldowan stone tools would have allowed early humans access to brain and marrow from a broad range of animals obtained by scavenging or hunting - including some species larger than those from which chimpanzee hunters preferentially extract brain tissue and marrow fat. These and other carcass fats were probably prized by the early hominids as they are by recently-observed modern human hunter-gatherers. (Steffanson, 1960) More animal fat in the diet meant not only additional energy , but also a source of ready-formed long chain PUFAs, including AA, DTA(docosatetraenoic acid (DTA, C22:4, w-3), and DHA. These three fatty acids together make up over 90% of the long chain PUFA (i.e. the structurally significant and biochemically active fat) found in the brain gray matter of all mammalian species. (Sinclair, 1975)

A cardinal feature of human evolution has been development of increasing brain size: Homo sapiens’ cranial capacity is thrice that of Australopithecus afarensis. A prime selective force driving this increase was almost certainly the complex nature of social interactions among early hominids. There is, however, no a priori reason to assume that such interactions, at first, differed much from those of chimpanzee and gorilla ancestors. Social complexity was thus a necessary, but insufficient, selective pressure acting to increase brain size . Another necessary factor was probably adequate dietary substrate to allow formation of brain tissue. (Crawford, 1992) The limiting raw materials, AA, DTA and DHA, could have been provided by animal tissues as hunting and/or scavenging activities assumed greater importance in human subsistence. (Eaton, 1998) Increasing complexity of interpersonal and social interactions together with availability of animal tissues - to provide the necessary structural lipid - constituted a unique psychonutritional nexus which may explain human brain expansion.

Dramatic nutritional, anatomic, and behavioral changes accompanied hunting and scavenging: division of labor by sexes, increased day range, reduced sexual dimorphism, decreased gut size, greater stature and increasing brain size. (Leonard & Robertson, 1994; Aiello & Wheeler, 1995) However, it is important to recognize that these changes were gradual. H. habilis evolved into H. erectus over the course of several hundred thousand years and this rate of cultural change, in all likelihood, allowed for concomitant genetic modification. The behavior, subsistence and biological characteristics of anatomically modern Late Paleolithic humans differed strikingly from those of H. habilis, but these changes developed over a 2.5 million year period. In contrast, subsequent comparably dramatic changes in both behavior and subsistence have occurred with far greater rapidity, almost certainly overmatching the capacity of genetic evolution to keep pace.



The Neolithic

Adoption of agriculture and animal husbandry, while perhaps not explosive enough to justify being termed a "revolution", nevertheless generally required only a few thousand years and, in some cases, only a few hundred. Genetic evolutionary responses must have been evoked by the altered circumstances, but given the time frame, only high order selective pressures (e.g. newly appearing epidemic infectious diseases capable of killing young people before the age of reproduction) have had sufficient time to significantly impact the human genome.

The chief dietary innovation which accompanied agriculture involved cereal grains. Earlier humans recognized that grains could be consumed in times of shortage; however, with primitive technology, the work involved in milling grains to render them digestible was sufficient to discourage their routine use. But when population density reached the point that nomadic exploitation of game and wild plant foods became difficult or impossible and mesolithic humans adopted a more settled way of living, utilization of cereals became attractive. Actual crop cultivation followed and, in most areas, cereals became staples. This nutritional departure was unparalleled; no other free-living primates routinely consume cereal grains. (Milton, 1993)

Increasing dependence on cereal grains as an energy source decreased dietary breadth and necessarily reduced consumption of fruits and vegetables which had been prime foodstuffs throughout primate and hominid evolution. Paleolithic humans commonly obtained 65% of their food energy from fruits and vegetables (often from 50 to 100 individual species over a year’s time), but becoming dependent on grains may have reduced intake of fruits and vegetables to 20% or less of total energy intake. Accordingly access to micronutrients (vitamins, minerals and phytochemicals) previously supplied by fruits and vegetables was substantially decreased . Of course, cereal grains also provide micronutrients, but not necessarily those to which human biology became accustomed throughout a multimillion year evolutionary experience during which fruits and vegetables were the overwhelmingly dominant plant foods.

For pastoralists, consumption of animal protein probably continued at approximately Paleolithic levels, but for most agriculturalists, meat was less available than it had been for Stone Agers. This change may have been a factor in the stature decrease which accompanied transition from foraging to agriculture. (Cohen, 1989) Less meat together with cereal grain preponderance increased the w-6 : w-3 PUFA ratio and also reduced intake of preformed longer-chain PUFAs, including AA, DTA and DHA.

The fiber available from rice and wheat is predominantly insoluble while that from fruits and vegetables is mainly soluble, hence while total fiber intake probably changed little, in the old world agriculture generally increased the insoluble:soluble dietary fiber ratio. (Eaton, 1990)

Further dietary changes which occurred during the agricultural millennia included development of alcoholic beverages, commercial salt production, and the gradual spread of sugar cane cultivation. Each was new in primate/hominid experience and each has had profound consequences for human health.



Industry and Diet

The industrial era and agribusiness have further distanced nutrition from its primate and Paleolithic antecedents. Roller-milling has reduced the fiber content of cereal grain-based foods so that total fiber intake has plummeted to levels much below those obtaining for agriculturalists, hunter-gatherers, or primates. (Eaton, 1990) Cold-pressing has facilitated extraction of vegetable oils (e.g. corn, sunflower, safflower) rich in w-6 PUFA and thereby exacerbated the w-6 : w-3 imbalance existing in the diets of affluent nations. (Simopoulos, 1991) The pricing structure for beef and other commercial meat has, until recently, rewarded breeding and feeding practices which maximize carcass fat deposition. This fat is deposited as an energy reserve, not for structural purposes, so its content of saturated, serum cholesterol-raising fatty acids is high. And not only do commercial meat animals have more depot fat than do their wild relatives; because they are now fed grain instead of forage, the w-6 : w-3 partition of their lipid is highly unnatural, with a marked w-6 excess. (Marmer, 1984).

Foods popular in late 20th century affluent nations include a profusion of commerc ially-prepared items. Humans are the only free-living species to consume such foods, whose natural origin is obscure, and the entities created by the food industry commonly provide inapparent salt, refined flour, sugar or corn sweeteners, and trans fatty acids in extraordinary concentration.

Another characteristic feature of contemporary nutrition is the unprecedented availability of food energy. If there were some way to judge the human effort necessary to obtain a given amount of food energy, citizens of existing Western nations would almost certainly "enjoy" the highest calorie-to-effort return ratio yet experienced by humans and their hominid,hominoid, or primate ancestors. We have "optimized foraging" to an unprecedented degree and while an advantage in some respects, this relationship has adverse health implications as well. Because energy expenditure and energy intake have been largely uncoupled in contemporary affluent nations, growth and development are unnaturally accelerated while abnormal body composition (hyperadiposity and musculoskeletal deficiency) have become unprecedentedly common. The consequences range from insulin resistance and diabetes to age-related fractures. (Eaton & Eaton, 1998)



Dietary Discordance and Chronic Diseases
The altered nutritional parameters which differentiate contemporary diets from Paleolithic and primate patterns impact health in many ways, some beneficially (e.g. greater life expectancy), but many adversely. Five examples of deleterious effects include:

1) Electrolytes and blood pressure - Humans are the only free-living terrestrial mammals who ordinarily consume more sodium than potassium, the only species to commonly experience rising average blood pressure with increasing age, and the only mammals to commonly develop hypertension. Stone Age humans consumed only one fourth the sodium average Westerners now do (Eaton, 1997). About 90% of current sodium intake results from food processing, preparation and flavoring: only 10% is intrinsic to the foods themselves. Many groups of hunter-gatherers, pastoralists and rudimentary horticulturalists who lack commercially available salt have been studied in this century: these ancestral human surrogates experience neither rising blood pressure with age nor clinical hypertension. (Eaton, 1988)

2) Cereal grains and cancer - No primates other than humans ordinarily consume cereal grains, but from the introduction of agriculture onwards grains have been the single most important contributor to human food energy, providing from 40 to 90% of human caloric requirements. In doing so they have displaced fruits and vegetables which, until the Neolithic, had been the dominant energy source for Stone Agers, earlier hominids and our antecedent primate ancestors for 50 million years. A recent comprehensive analysis (150 scientists reviewed 4500 research studies) puts this phenomenon into perspective (World Cancer Research Fund & American Institute for Cancer Research, 1997). The influence of dietary variables on 18 different cancers was assessed. Vegetables were found to exert a convincing preventive effect for five cancers, a probable preventive effect for four others, and a possible preventive effect for another seven. For fruits the analysis revealed four convincing, four probable and four possible preventive relationships. But for cereal grains there were no convincing or probable preventive relationships, only one possible preventive effect and, for one cancer (of the esophagus) grains may possibly have increased risk.

In short, the best available evidence suggests that vegetables and fruits have far more cancer-preventing potential than do grains. This probably reflects the phytochemical content of fruits and vegetables, phytochemicals to which current human biology became adapted through many million years of evolutionary interrelationships. The phytochemicals of grains have interacted with the human genome for only 10,000 years, hence substitution of grains for vegetables and fruits in human diets might readily diminish our resistance to development of neoplastic disease.

3) Energy intake/output uncoupling and insulin resistance - For primates and other mammals in natural settings food procurement is inextricably linked to energy expenditure, a relationship which establishes a range of body composition appropriate for any given species. The ratio of fat to muscle generally varies with season, but typically within fairly narrow limits; hyperadiposity, as it exists for many contemporary humans, is rare or nonexistent for other primates. The necessity for physical exertion, unavoidable for most humans until the industrial era and, especially, the 20th Century, ensured substantial muscularity, in the proportionate range existing for current free-living nonhuman primates. In the present, however, obtaining food energy is no longer dependent on muscular exertion: from childhood on, calories are available at the lowest cost in human experience without reciprocal energy expenditure. The result is relative sarcopenia - deficiency of skeletal muscle. For many individuals in affluent nations the proportions of adipose tissue and skeletal muscle are grossly out of line with what obtained during prior evolutionary experience.

Both fat and muscle take up glucose from the blood in response to insulin stimulation, but the capacity of muscle in this regard far exceeds that of adipose tissue per unit weight (DeFronzo, 1997). Existing control mechanisms for carbohydrate homeostasis were established over evolutionary time during which ancestral body composition almost never approached the extremes of hyperadiposity and sarcopenia manifested by many contemporary humans. For such individuals a given insulin secretory pulse, in response to a carbohydrate-containing meal, now produces less reduction in blood glucose levels than would have been achieved for prior humans with evolutionarily "appropriate" body composition. Additional, "extra" pancreatic insulin secretion is required to produce glucose homeostasis. This constitutes functional insulin resistance, a pathophysiological state exacerbated by low muscular metabolic activity (another result of exercise deficit). (Eaton & Eaton, 1998) In genetically susceptible individuals the process can proceed to glucose intolerance and overt diabetes. Prevalence of type 2 diabetes (that related to insulin resistance and, by far, the most common form) has multiplied 10-fold in the United States since the 1930’s (American Diabetes Association, 1996) as the increasing disconnect between caloric accessibility and energy expenditure has produced and ever-larger number of obese, sarcopenic Americans.

4) Dietary fat and coronary heart disease (CHD) - While many other dietary, behavioral and genetic factors influence the inception and progression of coronary heart disease, hypercholesterolemia is a paramount factor. Recently-studied hunter-gatherers have serum total cholesterol levels averaging 125 mg/dl (Eaton, 1988), a value within the range for free-living non-human primates (Eaton, 1992). Human societies with similar average serum total cholesterol levels have vanishingly low prevalences of CHD. Americans and other affluent Westerners, conversely, have average total serum cholesterol values exceeding 200 mg/dl - well outside the "natural" primate range - and, for these populations, CHD is the single leading cause of mortality.

Evidence linking dietary fat to serum total cholesterol concentrations is incontrovertible: the prime agents are saturated and trans fatty acids. For ancestral humans the cholesterol-raising saturated fatty acids constituted about 5% of total energy intake and trans fatty acid intake was almost negligible. For Americans, cholesterol-raising saturated fatty acids approach 15% of dietary energy while hydrogenated vegetable fats and oils provide an unprecedented quantity of trans fats (Eaton, 1997).

The w-6 : w-3 imbalance in current Western diets also affects coronary disease. Excessive w-6 AA relative to w-3 DHA and eicosapentaenoic acid (EPA, C20:5, w-3) adversely affects platelets and arterial walls so as to promote development of coronary atherosclerosis. (Riemersma, 1992) The more balanced w-6 : w-3 dietary PUFA intake of Paleolithic humans would have negated this effect.

5) DHA deficiency and the brain - While human cranial capacity tripled over the 2.5 million years after H. habilis first appeared, this trend has recently reversed. Since peaking among Cro Magnons and other humans living during the Late Paleolithic, cranial capacity has fallen off about 11%. (Ruff, 1997) This diminution has paralleled a decrease in consumption of animal foods and, consequently, a diminished dietary intake of preformed long chain PUFA, the building blocks necessary for formation of brain tissue. These PUFA can be synthesized by humans from their 18 carbon precursors, LA and ALA, but the process appears too slow to supply the amounts of AA, DTA and DHA needed for optimal brain growth during fetal development and infancy. (Woods, 1996; Salem, 1996) DHA deficiency is especially important, first because its concentration in brain tissue exceeds those of AA and DTA and second, because our current w-6 excess tends to promote formation of long chain w-6 AA and DTA while inhibiting synthesis of w-3 DHA. Association is not necessarily causation, but the fluctuations which have occurred in brain size over evolutionary time, both increases and decreases, correlate well with dietary intake of the preformed long chain PUFA necessary for formation of brain tissue so it is tempting to speculate on a causal relationship.

Current w-6 : w-3 imbalance together with absolute dietary DHA intake quite low in human evolutionary perspective may be relevant to the frequency of unipolar depression, a debilitating neuropsychiatric disorder which accounts for more "disability adjusted lost years" in the total world population than heart attacks, lung cancer or AIDS. (Murray & Lopez, 1996) Prevalence of depression has increased substantially during the 20th Century (Klerman & Weisman, 1989; Weisman, 1996) while dietary intake of w-6 PUFA has soared relative to that of w-3 PUFA, primarily because of increased vegetable oil consumption and corn-feeding of commercial meat animals. Fish are good sources of w-3 PUFA (including DHA) and national fish consumption is inversely correlated with national rates of depression (Hibbeln, 1997). Furthermore, studies of plasma w-6 : w-3 ratios in patients with depression reveal a direct association: higher ratios of w-6 to w-3 PUFA are correlated with more frequent and severe depressive episodes. (Adams, 1996; Hibbeln, 1997) Early therapeutic trials with w-3 PUFA have shown symptomatic improvement. (Hibbeln & Salem, 1995) These findings are preliminary and, as yet, only suggestive, but their implication is that an w-6 : w-3 dietary ratio (and perhaps magnitude) similar to that which obtained throughout human evolutionary experience may be an integral component of mental health.



Conclusion

Deviations from the postulated ancestral primate nutritional baseline have had important evolutionary impact and they appear to influence human health in the present . Because of these significant relationships, better understanding of primate nutritional patterns would be desirable. The diets of Miocene and Pliocene apes are particularly relevant and the goal would be to estimate as accurately as possible the nutrition of the last common ancestor of existing pongids and humans.

Toward this end establishing relationships between dentition and nutrient intake would be extremely valuable. While folivorous primates presumably exhibit interspecific nutritional variation, there may be generalizations about such diets which are valid across broad subsistence categories.

Bioarchaeology, assessing lifetime experience from archaeological sites and skeletal-dental remains, may aid in assessing primate diets through evolutionary time. Craniofacial adaptations as well as isotopic and elemental dietary "signatures" may provide important clues.

Another area of necessary research involves proximate analyses of the foods consumed by primates generally and by pongids especially. In order that these can be conveniently related to current and past human nutrition, the analyses should provide wet weight data. Both macro- and micronutrient compositional values will be helpful, including analyses (e.g. individual lipid species) not commonly performed. Once a sufficient body of proximate analyses for the plant foods, insects, and small mammals consumed by primates has been assembled, and the proportions of such foods making up differing primate diets determined, modeling representative average nutritional intake for primates with varying subsistence patterns should become possible. And, in turn, this information will permit estimation of the last common ancestral diet.

The above research "wish list" is a tall order, but the potential for expanding understanding of primate, hominoid, hominid, and human evolution together with the benefit for health promotion based on evolutionary medical principles should provide more than sufficient incentive for the investigational effort.




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Eaton seem to have a mission of painting Paleo ancestors with a low-fat, fruit and vegetable dietary tendanceis, just like Ornish. Notice that his reference for this claim is his own "study" in 1998. That "study" originally appeared in the New England Journal of Medicine, 1985 with a table under a title of "possible" food composition. Those possibiliteis were calculated based on a couple of modern day forager sociteis, all tropical.

What these scientists fail to realize is in the paleo era, fruits and vegetables were hard to find, and were seasonal treats, not in constant supply.

They also ignore the Eskimo societeis, were there's nothing to eat but fat and meat.

Wa'il

Hello Wa'il, I knew if only one person read this article, it would be you.

I think you missed something though. That section on total fat intake being low was in pre-man. He is talking basically about a pre-man vegetarian ape pre-human primate called a hominoid as opposed to a hominid. As you can see from the next section where hominids (earliest forms of man--our earliest ancestors after the branch from apes) starting he says with Australopithecines (like Lucy) ate lots of fat and meat. That's his point! Hurray!

Hi Voyajer,

You are correct, I read this peice with a particular bias against Eaton himself and his numeric assumptions, which may have mislead many LC writers, such as Dr. Cordain.

However, the comment he made was based on his earlier study of Paleo foragers "Paleolithic Nutrition", not primates. And when he says "greater availability of animal fat", he mostly likely meant greater than too low , and up to 20-22% fat as his paper asserted.

I may be wrong, if he has another 1998 paper on primates as well, do you know?

Wa'il

I know that Eaton started out in 1985 with Paleolithic Nutrition with a very low protein estimate. And he continued with this low estimate in Paleolithic Nutrition Revisited in 1997. However, you can see him here bending slowly away from this opinion. For one thing, he had to. The Paleontological community had just accepted the Expensive Tissue Hypothesis of Aiello Wheeler in 1995. Now it is in all text books and required reading at all universities. This Expensive Tissue Hypothesis says that the human brain could not have increased to that of modern man without the addition of a lot of meat and animal fat. Man and primates' basal metabolic rates are similar, but it takes more fuel for a larger brain, therefore our intestines became smaller which meant we could no longer eat bark and had to eat high quality/high energy foods like animal products to get enough calories and nutrients and fats (brain needs fats) to evolve a larger brain. Eaton had to relent and re-arrange his thinking which this 1998 essay shows his trend toward doing. You will also note in his conclusion a plea from him that more research needs to be done as he says that it is possible with more research to reconstruct a better picture of Paleolithic Nutrition (He obviously wasn't satisfied with his previously published views.)

Then in 2000 Eaton collaborated with Cordain on re-examining the basis for reconstructing Paleolithic Nutrition. (see Hunter-Gatherer, Dr. Eades unlisted PPLP references here on this forum). As Dr. Eades says in PPLP, the studies were all based on present day hunter-gatherers according to Lee's interpretation of the Ethnographic Atlas. However, as Dr. Eades points out, Lee was wrong. He included hunter-gatherers eating of shellfish as gathering and then Eaton concluded in 1985 that gathering was plant based and everyone has gone by this since. Cordain saw the error and Eaton himself got in on the study. Cordain and Eaton together proved by re-examining the Ethnographic Atlas that (and I quote:)



So Eaton wrote the definitive work on Paleolithic Nutrition in 1985 based on the definitive work by Lee done earlier which was wrong. Eaton (or I should say the Eatons who work together) have changed their tune.

This quote tells me they don't seem to have changed much

Note when they say animal food, they don't mean animal fat, so 45% animal food impleis 55% from fruits and vegetables, and 20% or less from fat.

Note the term "whenever ecologically possible." It is most likely impossible, in the paleo era, to find enough fruits and vegetables throughout the year to supply over 50% of the daily caloric requirement, assuming it was the preferred source of food, which is unlikely.

To me, they have the theory straight, but are too ashamed to come out and state the logical numbers derived from this theory, in order not to look like "low-carb fad diets" as Cordain likes to call them.

They make me see images of cavemen and cavewomen who line up to register their Weight Watchers points at paleo weigh-in centers

Wa'il

Note, I'm not all against their work and reserach, which I admire , I'm just trying to filter out some the fat phobia , which I think is cluttering their conclusions.

As always, thanks for the excellent information you are providing!

Wa'il

Wa'il, (what kind of name is that anyway? Hawaiian?)

I'm still not sure if I agree with your interpretation. You see, Eaton said that if hominoids ate 95% plant food, they would still be getting extremely low carbohydrate.



I don't know how he figures, but I would say this means that the 45% animal product/55% plant product would mean that the 55% plants would still be a low carb diet. How? I don't know, but it appears to be what he's saying.

Perhaps it had to do with having 200 g fiber per day. 50% of calories were fiber it says. (The term energy and calories are interchangeable in the literature. A low energy diet means a low calorie diet.) I see a big problem with his statement that 50% of energy/calories were from fiber as fiber has zero calories whether it's one gram of fiber or 10,000 grams of fiber, the calories are still zero. So how can you get 50% of calories from fiber?

With only 5% animal foods, these hominoids got a lot of protein:



How can you get more protein than contemporary humans while eating 95% plant foods? Now that is a good question. And if you are getting high protein from plants, how much fat is in these plants?

In view of Eaton's comments above, I can't believe that he is trying to say that the up to 65% of calories from fruits and vegetables for Paleolithic man is all carb. (He was still dependent on the work of Lee 1968 here in this 1998 essay, because he hadn't done the Cordain study of 2000 yet. He quotes Lee as his source.) Somehow I think he's still saying there was a great deal of fiber and protein in this part of the Paleolithic Diet.

Besides since the Cordain-Eaton collaboration of 2000, Eaton has changed his tune and taken a back seat to Cordain.

This recent article of 2002 by Eaton and Cordain shows a marked change in the carbohydrate to fat ratio with lowest estimate of fat being 28% and highest being 58% which is pretty much a ketogenic diet:

Eur J Clin Nutr 2002 Mar;56 Suppl 1:S42-52

The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic.

Cordain L, Eaton SB, Miller JB, Mann N, Hill K.

Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado, USA. cordain~cahs.colostate.edu

OBJECTIVE: Field studies of twentieth century hunter-gathers (HG) showed them to be generally free of the signs and symptoms of cardiovascular disease (CVD). Consequently, the characterization of HG diets may have important implications in designing therapeutic diets that reduce the risk for CVD in Westernized societies. Based upon limited ethnographic data (n=58 HG societies) and a single quantitative dietary study, it has been commonly inferred that gathered plant foods provided the dominant energy source in HG diets. METHOD AND RESULTS: In this review we have analyzed the 13 known quantitative dietary studies of HG and demonstrate that animal food actually provided the dominant (65%) energy source, while gathered plant foods comprised the remainder (35%). This data is consistent with a more recent, comprehensive review of the entire ethnographic data (n=229 HG societies) that showed the mean subsistence dependence upon gathered plant foods was 32%, whereas it was 68% for animal foods. Other evidence, including isotopic analyses of Paleolithic hominid collagen tissue, reductions in hominid gut size, low activity levels of certain enzymes, and optimal foraging data all point toward a long history of meat-based diets in our species. Because increasing meat consumption in Western diets is frequently associated with increased risk for CVD mortality, it is seemingly paradoxical that HG societies, who consume the majority of their energy from animal food, have been shown to be relatively free of the signs and symptoms of CVD. CONCLUSION: The high reliance upon animal-based foods would not have necessarily elicited unfavorable blood lipid profiles because of the hypolipidemic effects of high dietary protein (19-35% energy) and the relatively low level of dietary carbohydrate (22-40% energy). Although fat intake (28-58% energy) would have been similar to or higher than that found in Western diets, it is likely that important qualitative differences in fat intake, including relatively high levels of MUFA and PUFA and a lower omega-6/omega-3 fatty acid ratio, would have served to inhibit the development of CVD. Other dietary characteristics including high intakes of antioxidants, fiber, vitamins and phytochemicals along with a low salt intake may have operated synergistically with lifestyle characteristics (more exercise, less stress and no smoking) to further deter the development of CVD.

Voyager, once the numbers no longer make sense to us, it simply means the numbers don't add up, and there's a flaw in the logic. They want to paint the hunter-gatherer societies with their vision of a "healthy balanced" diet, maintaining a very high ratio of fruits and vegetables, yet remain low-carb high-protein and little fat. It just can't be done, and they should just let the numbers reflect the real dietary values, without presenting any preconceived notion of what is a "healthy balanced diet" is.



With this one, the numbers are looking much better, yet still based on mainly tropical, modern HG societies.

Wa'il

Well, you can't expect miracles ... (sigh)

True, but it will take less than a miracle to straighten them out. With the recent discovereis of the fallaceis of low-fat diets, and mainstream media questioning the low-fat theory, scientists will have less reasons to be fat-phobic.

Wa'il