New research on the diet of Australopithecus Sediba has revealed another beautiful fact undermining the ugly Paleo DietTM theory. This recently discovered possible human ancestor that lived about 2 million years ago appears to have eaten an "almost exclusively" plant-food diet:
"Almost two million years after their last meals, two members of a prehuman species in southern Africa left traces in their teeth of what they had eaten then, as well as over a lifetime of foraging. Scientists were surprised to find that these hominins apparently lived almost exclusively on a diet of leaves, fruits, wood and bark."
This NYT article discussing the research contains an interesting comment from Benjamin H. Passey, a geochemist at Johns Hopkins University, who conducted the tests determining the high ratio of carbon isotopes indicating a diet mostly of plant foods:
"“One thing people probably don’t realize is that humans are basically grass eaters,” Dr. Passey said in a statement. “We eat grass in the form of the grains we use to make breads, noodles, cereals and beers, and we eat animals that eat grass. So when did our addiction to grass begin? At what point in our evolutionary history did we start making use of grasses? We are simply trying to find out where in the human chain that begins.”"[Emphasis added]
It doesn't look like anyone presenting at the upcoming 2012 Ancestral Health Symposium will be discussing the reality that humans evolved as primarily plant- and probably, grass-product eaters. In fact, it looks like someone there considers plants "A Little Shop of Horrors." Sigh.
Science like this shows that so-called "Paleo diet" advocates are way off track if they still think that grains, i.e. seeds of grasses, are only a recent addition to the diet of humans. The idea that an almost purely carnivorous species with no experience eating grass seeds just suddenly adopted a grain-based diet only 10K years ago, after more than 2 millions of years completely grain-free, simply strains credulity.
Put otherwise, the agricultural revolution must have been preceded by a long, increasingly symbiotic relationship between human ancestors and seed-bearing grasses. Although ancestral humans did consume variable quantities of meat, meat-consumption probably did not provide the key to human brain expansion or significantly alter human physiology from its baseline adaptation to a plant-based diet.
This new research reminds me of my June 19, 2011 post entitled "Gathering Wild Grains," wherein I wrote
"Put this together with evidence that Paranthropus boisei, a human relative dating to 1.4 to 1.9 million years ago, grazed on grass [2]. Paranthropus and humans both descended from Australopithecus, but the Paranthropus went extinct. To several scientists working with this information, this new data on Paranthropus suggests a reinterpretation of previously collected data on Australopithecine diet, i.e. that Australopithecus may also have eaten grasses.
"Perhaps we can start to put together a plausible path for the incorporation of cereal grains--grass seeds--into human diets. Perhaps human ancestors used grasses as food more than 2 million years ago. Human evolution might look something like this: the grass-eaters went extinct, but the grass-seed eaters thrived."
I am now even more confident that a grain-based, legume-enhanced diet is likely more ancestral than the Paleo DietTM . To celebrate, I am going to eat a big bowl of grass seeds and fruits, topped with legume milk, as soon as I finish this post.
I continue to read comments on my blog, and around the web, suggesting that anyone who believes that paleo diet is meat-based and low in carbohydrates is at least misinformed and at worst stupid. Supposedly, by the time I had written Farewell To Paleo [which I have updated with references supporting my supposedly subjective evaluation of meat-based diets], some panel of experts had already decided that paleo diet is not necessarily meat-based, nor high in fat, nor low in carbohydrates, and I was well behind the learning curve. Paleo 3.0 had arrived without my knowing it.
Or so some would like to think.
Perhaps unbeknownst to some people, "paleo diet" is short for "paleolithic diet," referring to the diet that humans evolved to eat during the so-called stone age. The people who originally promoted paleolithic diet as a modern method for supporting health and preventing disease conceived of a modern paleo diet as an attempt to replicate the salient nutritional features of the diet that supported human evolution using foods from the food groups believed to constitute prehistoric paleolithic diets.
Anthropologists, biochemists, and biologists who study the evolution of humans and human nutrition and the recent diets of hunter-gatherers have produced the evidence for the model of paleolithic diet that informs Loren Cordain's works. Among these people it seems there is a general agreement that prehistoric human diets were meat-based, high in animal protein and fat, and low in plants and carbohydrates. There are dissenters who have attempted to argue against this notion, such as Richard Wrangham and Katherine Milton, and, in the medical community, perhaps David Jenkins, but these individuals are in the minority. The majority adheres to some form of the Man The Hunter hypothesis, i.e. that increased carnivory separated the human line from our closest primate relatives; that increased meat-eating coupled with decreased plant-eating drove human evolution.
On February 21, 2012, after several people commenting on this blog had repeatedly tried to convince me that paleo diet is not necessarily meat-based, high in fat, or low in carbohydrates, Paul Jaminet posted the following message on the Facebook page for the Journal of Evolution and Health:
In case you have trouble reading it, it says:
"I'd like to welcome Miki Ben Dor to the journal effort. Miki was the lead author on the excellent recent paper "Man the Fat Hunter" http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235142/" [Jaminet forgot to hyphenate Ben-Dor's name.]
Does this paper depart from the hypothesis that prehistoric paleo diet was meat-based and assert that humans evolved on random combinations of meat, vegetables, fruits and nuts, so that any combination thereof constitutes a paleo diet?
No. Here is part of the abstract:
"We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins."
They believe that H. erectus in the Levant was so dependent on dietary fat (and meat, particularly of elephants) for survival, that the disappearance of the elephants drove them to hunt smaller animals, and this need to hunt smaller, faster, more agile animals coupled with a presumed physiological need for dietary animal fat provided a selective pressure that favored survival of a lighter, more agile, and smarter hominin, namely H. sapiens.
They expressly argue against the idea that human evolutionary diets could have been plant-based. For example, they state that human ancestors needed to consume animal fat because they couldn't eat enough plants to meet nutrient requirements:
"The need to consume animal fat is the result of the physiological ceiling on the consumption of protein and plant foods."
Under the heading "The Obligatory Animal Fat Dietary Model" they use the standard argument for an animal fat-based based paleolithic diet using the expensive tissue hypothesis; they think our supposedly small gut coupled with our large brain provide evidence that meat-eating fueled human brain evolution:
"The more compact, the human gut is less efficient at extracting sufficient energy and nutrition from fibrous foods and considerably more dependent on higher-density, higher bio-available foods that require less energy for their digestion per unit of energy/nutrition released. It would therefore appear that it was the human carnivorousness rather than herbivorous nature that most probably energized the process of encephalization throughout most of human history." [Emphasis added]
(Ben-Dor et al incorrectly state that encephalization took place during human history, when presumably it actually took place in prehistory, i.e. before written records.)
Under the heading "The physiological ceiling on plant food intake" they argue that plant foods could not have been a significant part of prehistoric diets for all the time-worn reasons given by previous paleo diet theorists: takes too much time to gather plants, impossible to get adequate calories from raw plants, too many toxins and antinutrients in plants, no control of fire by H. erectus, lack of large cecum in human gut.
You will find this passage in their paper:
"Similarly, modern hunter-gatherer (HG) groups, despite having access to fire and metal tools, also seem to have a strong preference for carnivorous foods over vegetal foods ([53]:682), a notion also supported by a recent study [75] that emphasizes limited consumption of carbohydrates by present day HG groups.
"Indeed, an analysis of nine HG groups for which detailed dietary information exists ([76]:166) shows that five groups, located in an area abundant in vegetation, consumed only a meager amount of plant foods (17% of calories on average)."[Emphasis added]
This paper also includes a line I think I might have read first in Paul Jaminet's book, The Perfect Health Diet: "In fact, the natural diet of mammals is a high-fat diet." (Apparently they imagine that no mammal could break this supposed general rule, not even it it was peculiarly dependent on glucose to fuel its extraordinary brain.)
So, there you have it: These archaeologists and anthropologists, like others before them, believe that humans probably evolved on (and presumably are presently adapted to) a diet consisting largely of meat and fat with "only a meager amount of plant foods" and "limited consumption of carbohydrates." They apparently believe that because we are mammals, our natural diet is a high-fat diet.
Apparently Ben-Dor et al have not gotten the update on paleo diet from the blogosphere. Anyone want to send them version 3.1?
Of course those internet experts know more about paleolithic diet than these anthropologists and archaeologists, right?
Just like Denise Minger, who admits having no formal training in statistics or medicine, knows more about statistics than Richard Peto, PhD, the Professor of Medical Statistics and Epidemiology from Oxford University who was elected a Fellow of the Royal Society of London (for the introduction of meta-analyses) in 1989, and was knighted (for services to epidemiology and to cancer prevention) in 1999, and worked on the Cornell-Oxford-China Project, right?
The same way that Anthony Colpo, who has no medical training and has never published any peer-reviewed cardiovascular disease research, knows more about atherosclerosis than WC Roberts, who has authored several books on cardiovascular disease, has spoken at more than 1,300 medical meetings, serves as editor-in-chief of The American Journal of Cardiology, and with colleagues published more than 1,150 peer-reviewed articles on cardiovascular disease in medical journals, right?
And Gary Taubes, a science writer with no experience in bench obesity or medical research, and no peer-reviewed publications in the field of obesity research, knows more about nutrition and obesity, than, say, George Bray, Ph.D., Boyd Professor and Chief of the Division of Clinical Obesity and Metabolism at Pennington Biomedical Research Center, who over his 40 year career has authored or coauthored more than 1,700 publications, ranging from peer-reviewed articles to reviews, books, book chapters and abstracts, primarily in the field of obesity research.
If you think I am falling for a fallacious argument from authority, you don't understand that fallacy. As explained at FallacyFiles.org, an argument relying on authority is fallacious only if in the question under consideration, 1) no expertise is necessary or possible, 2) the cited authority is not a recognized expert in the field, 3) the authority is expert, but not disinterested, or 4) the authority is an expert, but his opinion varies markedly from the consensus of experts in his field. Fallacy Files recommends this procedure for determining whether an argument from authority is fallacious or not:
To sum up these points in a positive manner, before relying upon expert opinion, go through the following checklist:
Is this a matter which I can decide without appeal to expert opinion? If the answer is "yes", then do so. If "no", go to the next question:
Is this a matter upon which expert opinion is available? If not, then your opinion will be as good as anyone else's. If so, proceed to the next question:
Is the authority an expert on the matter? If not, then why listen? If so, go on:
Is the authority biased towards one side? If so, the authority may be untrustworthy. At the very least, before accepting the authority's word seek a second, unbiased opinion. That is, go to the last question:
Is the authority's opinion representative of expert opinion? If not, then find out what the expert consensus is and rely on that. If so, then you may rationally rely upon the authority's opinion.
If an argument to authority cannot pass these five tests, then it commits the fallacy of appeal to misleading authority.
If you apply these five tests to Denise Minger's authority on the Cornell-Oxford-China Project, or Anthony Colpo's authority on diet and cardiovascular disease, or Gary Taube's authority on diet and obesity (or diet-related diseases), you will see who commits the fallacious appeal to authority.
Of course, the consensus could be wrong. But, when 50 or more years of research has produced enough evidence in support of a particular hypothesis to produce a wide consensus in a field, such as the lipid hypothesis, then you need really extraordinary evidence to overturn that hypothesis.
I highly doubt that Ben-Dor et al are going to change their view of paleolithic diet because some bloggers have decided that "paleo" includes plant-based diets with only meager amounts of meat and fat.
Just to be clear, I am not in this post agreeing, nor disagreeing, with any of the hypotheses of the Ben-Dor et al paper, so far as they apply to defining paleolithic diet or explaining the emergence of H. sapiens from H. erectus. Even if their hypothesis about how modern humans emerged is strongly supported by evidence I do not believe that it in any way establishes or strongly supports the idea that a meat-based, high-fat diet with a meager amount of plant foods and limited amount of carbohydrates best supports human health in a modern context. The direct way to discover the effects of foods on health of modern people in modern nations is to study the effects of various foods on modern people in modern nations, not speculate about how H. sapiens emerged.
In fact, if you believe that Ben-Dor et al have shown that a fat-based carnivorous diet is the best to support human health, I suggest you first subject them to the five tests to see if they are qualified authorities. I submit that anyone who asserts that a fat-based carnivorous diet is the best to support human health fails the last test, at least, and that anthropologists and archaeologists are not appropriately qualified authorities on diet, nutrition, or health care (test 3).
By the way, I wonder if Ben-Dor et al have any idea what hunting elephants entails. The video below shows primitive spear hunting, including hunting of elephants and hippos. Knowing the high level of intelligence and sensitivity of elephants (and the other animals as well), I find it appalling.
Thankfully we have evolved and found other ways to sustain ourselves in good health.
1) Nutrition as a science suffers from “chaos, disagreement, and confusion.”
And
2) Use of ‘an evolutionary model’ would elimate “chaos, disagreement, and confusion” by providing “coherent way to interpret the data.”
With regard to the first statement, I don’t know where he finds the “chaos, disagreement, and confusion” in nutrition science. I can’t find this in any standard nutrition textbooks, in the National Academy of Sciences Food and Nutrition Board Dietary Reference Intakes publications, or among various expert panels making dietary recommendations to the public. Among these scientific sources, I find very little or no debate as to human requirements for protein, fat, carbohydrate, vitamins, and minerals. Also, the general guidelines for diet vary little from expert panel to expert panel. Do I see a straw man here?
Or is Cordain preoccupied with the confusion among lay people, generated by the profusion of fad diet books?
Or is the disagreement he refers to the disagreement between his recommendation for a low-carbohydrate, high-protein diet, and the science which shows that humans only require a small amount of protein (one-third of what Cordain advocates) and lots of carbohydrates?
With regard to the second statement above, this implies that we should find even greater agreement among those who profess to use “an evolutionary model” to evaluate nutrition than we do among the conventional sources that Cordain derides.
In contrast, among those using an evolutionary model, Cordain believes that we should eat them because they provide important phytochemicals that protect against cancer and inflammation, but evolutionary model advocate and radiologist Kurt Harris, M.D. has once expressed the view that “plants and plant compounds are not essential or magic,” stating:
"Show me a randomized intervention that shows the benefits of fruits and vegetables. Such trials have been done and they have not shown a benefit."
Unfortunately I do not know to which trials he refers as he provided no reference. In that essay, Harris added that the idea that a particular plant compound is essential is inherently implausible and in need of a rigor of proof suitable for establishing the idea that there exists some extraterrestrial intelligence:
"To overcome the inherent implausibility of a particular compound or plant being essential or uniquely beneficial to health, there must be a high standard of proof.
"Similar to the level of proof there that there is extraterrestrial intelligence. It's implausible, so good evidence is needed."
Dr. Harris has amended his view on this topic somewhat since those words, and has written a blog indicating he believes that some plant compounds may provide benefits and "that eating some veggies is a hedge against going without unspecified beneficial compounds."
My question is, if the evolutionary model is so helpful for eliminating chaos and confusion, why didn't it clearly favor one or the other of these views about plants and plant compounds?
Nutrition science recognizes many plant compounds essential to health (although apparently not those that Dr. Harris had in mind in his 'plant compounds are not essential' essay). Those include, minimally, the vitamins thiamin, riboflavin, niacin, pyridoxine, pantothenic acid, folate, ascorbic acid, phylloqunione (vitamin K1), tocopherols (vitamin E); the essential fats linoleic and linolenic acids; and the essential amino acids isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine.
All of these compounds are originally synthesized by plants and, except for niacin, appear in animal tissues only because the animal ate plants directly or ate another animal that ate plants. The evidence that we require these plant compounds is thoroughly discussed in the various Dietery Reference Intakes publications of the Food and Nutrition Board of the National Academy of Sciences as well as numerous standard nutrition textbooks.
Amazingly, nutritional scientists discovered the essentiality of these nutrients for modern humans without speculating about the habits of stone age hunter-gatherers, consulting archaeologists, or asking anthropologists what isolated hunter-gatherers eat. Am I to believe that all of this talk of essential nutrients is nonsense because it was discovered without applying an evolutionary model?
In addition, while I would agree that it is implausible that any particular plant (e.g. spinach) is essential to health, plants world-wide have similar constituents (including non-vitamin phytonutrients). For example, polyphenols occur in many species of plants world-wide. To my knowledge, no nutrition scientist is arguing that any particular plant is essential or uniquely beneficial to human health, but many would suggest that humans have adapted to (possibly to become reliant upon) consumption of families of plant compounds (e.g. polyphenols). I find this considerably more plausible than the idea of extraterrestrial intelligence (I don't know if Dr. Harris has changed his opinion here), since we already have established a human need for the plant compounds I have listed above.
So far as I can tell, except for vitamin D, which our own bodies synthesize if exposed to sunlight, not one nutrient mentioned in those FNB documents as an essential dietary component for humans is originally synthesized only by animals; i.e. all are originally synthesized by plants or microbes, or present as inorganic components of the earth's crust. This table lists the essential nutrients and their original sources:
Nutrient
Original Source(s)
Essential amino acids (9)
Plants
Linoleic acid
Plants
Linolenic acid
Plants
Glucose
Plants
ß-carotene (provitamin A)
Plants
Tocopherols (vitamin E)
Plants
Cholecalciferol (vitamin D3)
Endogenous synthesis after sunlight exposure
Phylloquinone (vitamin K)
Plants
Thiamine (B1)
Plants and microbes
Riboflavin (B2)
Plants and microbes
Niacin (B3)
Plants
Pantothenic acid (B5)
Plants and microbes
Pyridoxine (B6)
Plants and microbes
Folate
Plants and microbes
Cobalamin (B12)
Microbes
Ascorbic acid (vitamin C)
Plants
Minerals
Rocks, soil (brought into the food chain by plants)
Cholesterol
Regarding dietary and blood cholesterol, scientific bodies consistently agree that dietary cholesterol is not beneficial or essential, and reducing cholesterol levels is desirable and necessary for avoiding cardiovascular disease (atherosclerosis). For example, the NAS Food and Nutrition Board writes:
"There is much evidence to indicate a positive linear trend between cholesterol intake and low density lipoprotein cholesterol concentration, and therefore increased risk of coronary heart disease (CHD). A Tolerable Upper Intake Level is not set for cholesterol because any incremental increase in cholesterol intake increases CHD risk. Because cholesterol is unavoidable in ordinary diets, eliminating cholesterol in the diet would require significant changes in patterns of dietary intake. Such significant adjustments may introduce undesirable effects (e.g., inadequate intakes of protein and certain micronutrients) and unknown and unquantifiable health risks. Nonetheless, it is possible to have a diet low in cholesterol while consuming a nutritionally adequate diet. Dietary guidance for minimizing cholesterol intake is provided in Chapter 11."
Let me emphasize some lines from this passage:
"There is much evidence to indicate a positive linear trend between cholesterol intake and low density lipoprotein cholesterol concentration, and therefore increased risk of coronary heart disease (CHD)."
"....any incremental increase in cholesterol intake increases CHD risk."
Of interest, this paragraph illustrates my previous point that the dominant nutrition paradigm includes Cordain's belief that elimination of animal foods from the diet "may introduce undesirable effects (e.g., inadequate intakes of protein and certain micronutrients) and unknown and unquantifiable health risks." This passage documents that Cordain's perspective is conservative, not revolutionary, compared to Campbell's, because, unlike Cordain and the Food and Nutrition Board, Campbell does not believe that eliminating cholesterol from the diet would result in protein or micronutrient deficiencies or 'unknown and unquantifiable health risks.'
Nevertheless, the Food and Nutrition Board maintains that dietary cholesterol (i.e. animal food) intake increases coronary heart disease risk. The National Heart, Lung, and Blood Institute concurs and adds that "the higher your blood cholesterol level, the greater your risk for developing heart disease or having a heart attack." Their publication "High Blood Cholesterol: What You Need To Know" includes this:
Again, no confusion or chaos apparent in the nutrition science Cordain has attacked.
"I do not believe in any of the versions of the lipid hypothesis, ranging from Ancel Keys' original idea that cholesterol or dietary fat clogs the arteries, to the currently fashionable one that “small, dense” LDL particles are like microscopic rodents that are designed to burrow under the intima of your blood vessels and kill you."
Why didn't their common use of an evolutionary model eliminate this disagreement?
Saturated Fat
Regarding saturated fat, scientific consensus documents such as the Food and Nutrition Board (FNB) of the NAS clearly state that we have no requirement for dietary saturated fat and any incremental increase in dietary saturated fat increases heart disease risk. Here again I quote the FNB Dietary Reference Intakes for Fats:
"Saturated fatty acids are synthesized by the body to provide an adequate level needed for their physiological and structural functions; they have no known role in preventing chronic diseases. Therefore, neither an AI nor RDA is set for saturated fatty acids. There is a positive linear trend between total saturated fatty acid intake and total and low density lipoprotein (LDL) cholesterol concentration and increased risk of coronary heart disease (CHD). A UL is not set for saturated fatty acids because any incremental increase in saturated fatty acid intake increases CHD risk." [emphasis added]
You will find that all major expert panels around the world maintain this position.
In contrast, among those claim to use the supposedly ‘unifying’ evolutionary model, Cordain believes the evolutionary model prescribes lean meat and low intake of dietary saturated fat, while Michael Eades, M.D. thinks that the evolutionary model prescribes fatty meat and high intake of saturated fat.
Should I really believe that the members of the Institute of Medicine's Food and Nutrition Board, composed of individuals who have invested their whole lives in studying nutrition both as scholars and bench scientists, do not understand the effect of nutrition on CHD risk, because they failed to use an evolutionary model? Do you think the members of the FNB know the difference between correlation and causation? Or did they get to the top of their field without mastering this concept presented in any undergraduate course in statistics or science?
Fitness
Regarding fitness, at least one advocates of looking at things with an evolutionary model, Art DeVany believes that the scientific data proscribes distance running (note: in the comments below Dr. Harris disavows using an exclusively evolutionary model to come to this conclusion), while Daniel E. Lieberman, a Harvard evolutionary biologist, and Dennis M. Bramble, a biologist at the University of Utah, believe that an evolutionary model prescribes distance running. If the evolutionary model is so powerful for eliminating chaos and confusion, why don't advocates of an evolutionary model agree on this point?
Confusion Within the Evolutionary Model
The ‘evolutionary model’ offered by Cordain and low-carbers also seems to introduce some confusion into the ‘evolutionary model’ itself.
According to this model, we should eat the imagined meaty low-carbohydrate diet of stone age mammoth hunters in order to increase our metabolic rates and lose body fat.
Does this make evolutionary sense?
I mean, would a high metabolic rate induced by a high protein/lean meat intake really benefit to a stone age hunter gatherer who already had difficulty getting hold of enough food to meet his metabolic needs?
And would a low body fat level achieved by a meaty low carb diet be an evolutionary advantage to humans dealing with extremely cold winters during the ice ages?
Groking the Source of Confusion
Could it be that Paleo advocates are confused and confusing because they rely on an imaginary Grok for their guidance rather than science?
By that I mean that the paleo diet ‘evolutionary’ model is based on largely imagining what stone age people did. In case you didn’t notice, we don’t have any body composition data, diet or medical records, photos, or videos from the stone age people the paleo crowd wants to emulate.
This means you have to use your imagination to come up with any picture of them and their diets and lifestyles. My imagination is different from yours, so we just might come up with different Groks to emulate.
I have realized that few if any of the conclusions in this document are subject to either confirmation or falsification. You can invent any number of 'models' of paleolithic diets and none can be either confirmed or falsified simply because we have no direct access to or records of East African Paleolithic human diets.
Let me put it this way. If I estimate that present-day Italian farmers consume 400 g of wheat bread and 3000 kcal per day in the winter, I can test my estimate by going to Italy, collecting diet records, and doing the math. Others can test my estimate by the same procedure. I could be proven wrong by someone else. But if I estimate that Neanderthal females consumed 1200 kcal, 500 mg of DHA, and 30 mg of vitamin C daily in the summer, neither I nor anyone else can test my estimate against reality because neither Neanderthals nor their habitat exist any longer.
Paleo diet proponents promote their viewpoint as a scientific revolution akin to the Copernican revolution.
In his contribution to The Protein Debate , Loren Cordain claims that “The study of human nutrition remains an immature science because it lacks a universally acknowledged unifying paradigm." Apparently he thinks other sciences are "mature," i.e. virtually completed, which would be news to physicists, astrophysicists, chemists, and biologists, most of whom know that we have only scratched the surface of the world we study.
He goes on to claim that “nothing in nutrition seems to make sense because most nutritionists have little or no formal training in evolutionary theory, much less human evolution. Nutritionists face the same problem as anyone who is not using an evolutionary model to evaluate biology: fragmented information and no coherent way to interpret the data.”
I don’t know why he thinks nothing in nutrition seems to make sense. Does he really think that if you open a textbook of nutrition, nothing in that book makes sense? Are those chapters telling us about the scientifically established nutrient requirements of humans just gibberish to him?
Perhaps he thinks this because there seems to be a general scientific consensus that we can improve our health prospects by reducing animal food consumption, but he prefers to eat a lot of meat. The American Heart Association, the American Institute for Cancer Research, and numerous other scientific medical organizations recommend eating more plant-based diets rich in fruits, vegetables, whole grains, legumes, nuts, and seeds, while reducing intake of animal products. Naturally, for someone who fervently believes in a low carbohydrate, high meat diet, the recommendations of the American Heart Association and the American Institute for Cancer Research don’t make sense.
Cordain sees his mission as providing a “universally acknowledged unifying paradigm” through his paleo diet hypothesis. According to him, we can ‘make sense’ of all the ‘confusing’ information he sees “By carefully examining the ancient environment under which our genome arose.” Here's a snapshot of his claim in The Protein Debate:
Certainly, nothing can be easier to do than examine the ancient environment under which our genome arose. We'll just get into our handy time machine that will take us back 200 million years to the emergence of the first mammals (a large part of the human genome emerged that long ago; we are a variation on a biological theme, not a totally unique entity) so we can “carefully examine” that environment first hand, rather than examine imaginary reconstructions offered by various creative minds.
Similarly Rob Wolf refers to non-believers in the paleo diet paradigm as similar to members of the “flat-earth society,” implying that paleo believers are akin to Copernicus, while non-believers are akin to those who still believe that the earth is ‘flat.’
Paleo advocates also claim to be bucking ‘conventional wisdom,’ again implying that they have the advance take on diet and everyone else is in the dark ages believing in the nutritional equivalent of a ‘flat earth.’
So let’s see, which of these two statements is more aligned with ‘conventional wisdom’ and which is more ‘revolutionary’ in the context of historical and recent beliefs about human nutrition, biology, and medicine?
Loren Cordain’s Paleo Belief: Humans must eat meat to obtain adequate protein and other nutrients, to build muscle mass and excel athletically, to maintain intelligence, and to maintain health. People can reverse disease by eating more animal products and less plant foods.
T. Colin Campbell’s Vegan Belief: Humans do not need to eat any animal products to obtain adequate protein and other nutrients, to build muscle mass, to excel athletically, to maintain intelligence, or to maintain health. We can reverse diseases by eating more plant foods and avoiding animal foods.
Given that approximately 98 percent of people in the U.S.A. eats meat on a daily basis, and many (including many paleo diet adherents) will immediately ask a vegan advocate “But where do you get your protein?” I submit that the paleo diet belief is far from revolutionary, indeed I might consider it reactionary.
Let me put it this way. At this present time, very few people accept the idea that a vegan diet can adequately provide protein and general nutrition to the average human, which explains why very few people eat vegan diets. Most people ‘believe’ that we need to eat meat, the way that, at the time of Copernicus, most people believed in a flat earth at the center of the sun’s orbit.
This belief in the importance of meat to human nutrition has a long history. I know of no time in Euro-American history when Campbell’s vegan belief was as widely accepted as the belief in a geocentric universe was at the time of Copernicus. On the contrary, the vegetarian perspective has been accepted by only a minority of people, mostly philosophers (e.g. Plato, Pythagorus) and medical doctors (e.g. Christoph Hufeland), throughout the history of Western civilization since the time of the Greeks.
In fact, T. Colin Campbell himself was initially indoctrinated to believe in meat and animal protein as critical to human health. It was only through research that he came to reject this widely accepted belief. That makes him more like Copernicus, challenging the widely held assumptions of his generation, whereas Cordain is simply agreeing with the long widely held belief that we have to eat meat to be healthy, smart, strong, and human.
Further, the idea that a vegan diet can reverse degenerative diseases contradicts the long-held belief of Western medical scientists that diet alone is inadequate for treatment of disease. The orthodoxy believes in eating meat and using drugs and surgery to treat disease. The revolutionary believes in avoiding meat and using a vegan diet as the primary tool in treatment of disease.
It seems to me that Cordain's paleo diet view aligns more with conventional wisdom and has more in common with the 'flat earth society,' and Campbell's vegan view bucks conventional wisdom and has more in common with Copernicus.
That’s my introduction to these two videos from PrimitiveNutrition which explore in greater depth the poor reasoning behind the paleo 'paradigm' starting with the fallacious appeal to nature (i.e. Eating meat is natural, therefore eating meat is optimal) which itself is based on a short-range view of 'natural' behaviors and their consequences (homicide is also natural, but if we all acted homicidal, we would be suicidal).
A much needed critical look at the fundamentals of paleo diet logic as offered by its leading proponents. I truly wish I had had the acumen to have done this degree of critical thinking before I got involved in, let alone invested in, paleo dieting.
I gave that title to the talk I will give at the Ancestral Health Symposium this Friday morning at UCLA.
I wrote this description of it:
For about 65 million years our primate ancestors consumed plant-dominated diets. Humans developed the technological ability to consume meat-based diets only within the last 2 million years, so at least 98 percent of the evolution producing our basic primate physiology occurred before humans could obtain meat-based diets.
Condensing the 65 million years of primate evolution into a 24 hour period, our ancestral diet was plant-based for at least 23 hours and 30 minutes, and animal-based diets emerged only within the last 30 minutes.
Ninety-eight percent of the human genome is identical to the nearest primate relative, chimpanzees, who eat a 95 percent plant diet. Recent hunter-gatherers consume up to 20 times more meat than chimpanzees on a percent energy basis, a substantial deviation from the primate baseline.
Similar to other primates, humans retain many physiological and behavioral features displaying adaptation to a plant-based diet, some of which are potentially maladaptive for diets supplying a high proportion of energy from meat, fat, or refined carbohydrates.Recent hunter-gatherers and pastoralists appear protected from maladaptive responses to animal-based diets by their baseline body composition, ecological context, low total energy intake, and evolved non-nutritive ingestive behaviors.
Modern people adopting meat-based ‘paleo-facsimile” diets may differ from recent hunter-gatherers in lifetime caloric balance, body composition, ecological context, and non-nutritive ingestive behaviors.By comparing hunter-gatherers and modern people, I show how the quality, quantity, and context of meat consumption will affect the outcome for any individual.
Plant and animal foods generally have opposite yet complementary nutritional characteristics.I present an integration of Chinese medical yin-yang theory with Western nutrition that can enable us to understand the relation each type of food (plant or animal) to modern diseases of deficiency or excess,and can help guide us to identify an appropriate dietary plant-animal ratio for any individual.
Time permitting, I plan to post a preview sometime later this week, and after the symposium, I will present the lecture in blog form.
"Over large areas of Africa people once obtained their basic subsistence from wild grasses. In certain places the practice still continues—especially in drought years (see boxes, pages 258 and 264). One survey records more than 60 grass species known to be sources of food grains.2
Despite their widespread use and notable value for saving lives during times of distress, these wild cereals have been largely overlooked by both food scientists and plant scientists. They have been written off as ''obsolete"—doomed since hunting and gathering started giving way to agriculture thousands of years ago. Certainly there has been little or no thought of developing wild grains as modern foods.
This deserves reconsideration, however. Gathering grains from grasslands is among the most sustainable organized food production systems in the world. It was common in the Stone Age3 and has been important almost ever since, especially in Africa's drylands. For millennia people living in and about the Sahara, for instance, gathered grass seeds on a grand scale. And they continued to do so until quite recently. Early this century they were still harvesting not insignificant amounts of their food from native grasslands.
However, in previous centuries the grains of the deserts and savannas were harvested in enormous quantities. In the Sahel and Sahara, for example, a single household might collect a thousand kilos during the harvest season.4 The seeds were piled in warehouses by the ton and shipped out of the region by the caravan-load. It was a major enterprise and a substantial export from an area that now has no equivalent and is often destitute."
If possible in relatively recent centuries, why not during the stone age?
If so, then what about leading up to that? Evolutionary explanations generally involve gradual changes over long periods of time. A species generally does not change its means of subsistence suddenly, or even over a few millennia. Adaptation to a new niche (if truly new) generally takes a very long time.
The hypothesis that grains were hardly ever consumed before about ten thousand years ago suffers from lacking a plausible explanation for why and how a species never adapted or even interested in cereal grains would so suddenly (on an evolutionary time scale) adopt a totally new behavior and means of subsistence.
Supposedly gathering grains would be a poor time investment for a forager. Put to the experimental test, this turns out to be untrue. From Kislev et al, "Impetus for sowing and the beginning of agriculture: Ground collecting of wild cereals" [1 full text]:
"We found that hand gathering of wild barley and emmer spikelets from the ground in Korazim and Mount of Beatitudes (Israel) is simple and efficient. About 0.25–0.5 kg (0.337 kg on the average) of pure grain could be gathered per hour by a single person, which provides on the average between a half and a whole day of the nutritional requirements for an adult individual."
So, in one to two hours a forager could collect enough wild grain to feed himself for a day, just collecting it off the ground by the handful. Eight hours of collecting could supply him with grain for a whole week. A smart forager would quickly come up with ways to make the work easier and more efficient. Kislev et al continue:
"Our results are in accordance with Harlan, who, after experimental hand stripping of pre-full-ripe ears of wild einkorn at Karacadag, southeast Turkey, claimed that in three weeks, a family group could gather more grain than it could possibly consume in an entire year (28)."
Three weeks investment for more food than you can eat in an entire year doesn't count as optimal foraging? More from Kislev et al:
"The significance of recognizing the practicality of spikelet gathering from the ground is that the gathering of large-seeded cereals as a staple food is not restricted to early summer. Rather, it can continue throughout the summer into the autumn, July through October, when the first heavy rains arrive and the dispersed grains begin to sprout. In other words, the collecting of grains from the ground would supply hunter-gatherers with a ready source of vegetal food until October, when acorns, their second most important plant resource, matured (29). The availability of acorns in October enabled them to invest part of the harvested grains for sowing. Moreover, stored grains and acorns would have provided nourishment until the following summer. There would then have been no period of vegetal food shortage due to seasonality of the two major harvests that helped support human groups in Western Asia at least from the beginning of the Upper Palaeolithic."
Has the bubble burst yet?
Put this together with evidence that Paranthropus boisei, a human relative dating to 1.4 to 1.9 million years ago, grazed on grass [2]. Paranthropus and humans both descended from Australopithecus, but the Paranthropus went extinct. To several scientists working with this information, this new data on Paranthropus suggests a reinterpretation of previously collected data on Australopithecine diet, i.e. that Australopithecus may also have eaten grasses.
Perhaps we can start to put together a plausible path for the incorporation of cereal grains--grass seeds--into human diets. Perhaps human ancestors used grasses as food more than 2 million years ago. Human evolution might look something like this: the grass-eaters went extinct, but the grass-seed eaters thrived.
I have experimented with eating a so-called “paleo” diet for at least 14 years. Although I had confidence enough in the concept to invest in self-publishing a book on putting it into practice, over this time I have endured increasing cognitive dissonance because the currently popular concept of paleo diet—animal-based, relatively high in protein and fat and relatively low in carbohydrate—conflicts with empirical nutrition knowledge accumulated over the course of 5 thousand years in both Asian and Western medicine, including a rather large body of clinical and laboratory data accumulated since the 19th century, all pointing toward humans being more adapted to a plant-dominated, high-carbohydrate diet supplying significantly less than 30% of energy from fat.
In addition, over this time period I have experienced myself, and seen in others, mostly gradual and sometimes sudden development of disorders that seem to occur regularly in people attempting to consume a high fat, excessive protein diet. I have made this connection because of my previous nutrition and health history combined with my formal training in both Western nutrition and Oriental medicine. To summarize, these unwanted changes have occurred:
1) General dry skin, and return of inflamed skin lesions in locations previously healed during my years eating a low-fat, plant-based diet, plus emergence of lesions in new locations. When I restrict total dietary fat to no more than 20% of energy and avoid red meat and saturated fats, I watch my skin heal, and conversely, when I eat more fat, saturated fats, poultry, and red meat I watch it worsen. By elimination and reintroduction, I have found that eating 6-8 ounces of grass-finished beef will within 24 hours noticeably increase skin itching.
[Update 3/20/12: For references, see my post on arachidonic acid provided by all types of meat, discussing the evidence that excess dietary AA promotes inflammation including skin inflammation found in typical skin disorders like eczema and psoriasis, here. Also my post discussing the evidence that heme iron found only in meat promotes inflammation, here.]
In general, it is standard practice in Chinese medicine to recommend elimination of red meat and poultry from the diet of people with inflammatory skin conditions because long empirical experience as well as Chinese theory indicate that these foods create inflammation (we say that they create heat). Despite my training in both Chinese medicine and Western nutrition, I tested the paleo hypothesis that these problems are caused by grains. My experience confirms the Chinese medical view that inflammatory skin conditions arise, not from eating benign gluten-free grains and starches, but from general blood inflammation, toxicity, and stagnation, promoted by heating, congesting, i.e. inflammatory foods such as meat and fats rich in arachidonic acid (for references see here).
From a Western nutrition perspective, excess dietary protein loads the blood with unnecessary acid, ammonia, and urea, and increased dietary fat causes increased coagulability of the blood, which reduces the rate of blood flow, particularly through the fine capillaries, impairing delivery of nutrients and oxygen to and removal of wastes from the skin cells as well as reducing the rate of blood filtration by the liver and kidneys; resulting in chronic low level toxemia. (3/20/12 Update: For references documenting the effects of fats on blood coagulation and flow, see this , and this.)
2) Gradual return of disabling seasonal allergies and sinus congestion and inflammation, along with chronic congestion of ear canals. Reduction of dietary fat and protein quickly reduced the symptoms and thinned the secretions. Prolonged high fat and protein intake appears to increase the thickness and hence stickiness of mucous in the respiratory tract, trapping dust, pollen, and other irritants that stimulate immune and inflammatory responses.
3) Intermittent bouts of severe abdominal distress clearly caused by high fat intake, from which I could get relief only by fasting followed by reduced fat intake for several days.
4) Irregular bowel movement and, when eating very low fiber, constipation with small, dry, difficult to eliminate stools. Tracy had the most problem with this. High fat intake slows intestinal peristalsis, reducing the reliability and frequency of elimination. (By the way, I have eaten 1.5 to 2.0 pounds of fruits and vegetables daily, providing 50 to 100 grams of fiber, most of the time I have eaten 'paleo,' which I reported in detail in my book, The Garden of Eating. Tracy ate similar or greater volumes of plants, so her severe irregularity was NOT caused by too little fiber. Tracy only got relief by cutting the fat.)
[Update 3/20/12: I neglected to provide the reference: Whitney and Rolfes, Understanding Nutrition, 10th Edition, p. 91: "When fat is present, intestinal motility slows to allow time for its digestion."]
5) [Update 3/20/12] Small yellowish lipomas, also called xanthomas, which have arisen twice during the 14 year paleo stint. Xanthomas occur particularly in people with high blood lipids, which I had for years while eating paleo (total cholesterol of well over 200).
The first time they appeared, I eliminated them by eating a very low fat grain-based diet for one period of about 6 months, then returned to eating a 40-60% fat diet rich in red meat. After another five years or so they returned again. Xanthomas include xanthelasmas, an accumulation of cholesterol under the skin of the eyelids. Oriental medicine considers these xanthomas external signs of internal lipid accumulation (e.g. in the arteries), and research confirms that xanthelasmas are indicative of increased risk of cardiovascular disease.
6) Increasing muscular stiffness in mornings after sleep, along with severe cramps in lower legs occurring regularly at night, especially with very low carbohydrate intake. The chronic morning stiffness quickly markedly reduced (about 3-4 weeks) after adopting a low fat intake. I attribute the stiffness to sluggish blood circulation due to increased blood coagulability impairing nutrient and oxygen delivery and waste removal from tissues at night.
7) Anxiety attacks, which I never experienced before, when eating low (20-25% energy) carbohydrate and high (50-60%) fat. The attacks occurred consistently after large fatty meals. I attribute this to poor circulation to the brain along with neurotransmitter imbalance caused by inadequate intake of dietary carbohydrate.[Update 3/21/12: This study found that people on a low carbohydrate diet for 52 weeks scored higher on scales of anger-hostility,confusion-bewilderment, and depression-dejection than people on a low fat diet for the same length of time.]
8) Chronic tension in the shoulders and neck, which decreases when eating less fat and more carbohydrate. Oriental medicine explains this as an effect of excess dietary fat on liver and gallbladder functions, affecting the circulation in the gallbladder channel which traverses the neck and shoulders.
[Update 3/20/12: I guess I should have documented that excess dietary fat can impair liver and gallbladder function. Try searching PubMed with "high fat diet and NAFLD" or "high fat diet and NASH"and you will find plenty of evidence that high fat diets can induce fatty liver disease, like this, and this, or this, and fatty liver disease promotes gallbladder disease
I will give more details about my more than 30 years search for health through nutrition and natural medicine in another blog.
My wife Tracy, who now blogs at The Food Way, had the following distressing developments over the course of just 12 months eating in a low- to moderate-carbohydrate, grain-free paleo/primal fashion:
1) Progressive gain of body fat, due to a positive fat/calorie balance. Simply, it was easy for her to overconsume calories when eating high fat foods.
2) Headaches and tension that increased in intensity over the 12 months.
3) Increasingly persistent right hypochondrial discomfort (discomfort under the ribs), a clinical indicator of stress to the liver.
4) Constipation of increasing severity over the course of the 12 months, due to dietary fat impairing intestinal peristalsis. (Reference given above.)
5) General and increasing sense of fatigue and morning sluggishness with increasing craving for morning coffee, an effect predictable from Chinese yin-yang theory applied to food. Briefly, a high-fat diet contributes to congestion and stagnation, and coffee's bitter constituents break up the congestion and drain out the stagnation, so people eating high fat diets can find the effects of coffee very attractive or even essential to get things opened up and moving.
6) Gradually increasing premenstrual breast tenderness and fibrocystic changes. This was the most alarming symptom to me, because it indicates increasing endocrine imbalance and is unacceptable within Chinese medical gynecology, which recognizes it as an early warning sign for potential breast tumors.
[Update 3/20/12: This study showed that women with cystic breast disease and breast pain have abnormally elevated levels of prolactin when on a high fat diet, but when they switch to a low (20%) fat diet this abnormality disappears.]
7) Persistent muscular and joint aches and pains, due to impaired blood flow.
8) Increasing vasomotor disturbances resulting in hot flashes and night sweats, another sign of endocrine imbalance. This disorder is also unacceptable to Chinese gynecology and Western scientific research has found that the occurrence of vasomotor disturbance in perimenopausal women is related to fat content of the diet, with high fat diets promoting and low fat diets reducing the occurrence.
9) Towards the end of the 12 months, she developed regular bloating after our high fat, meat-based meals, a sign of growing fat intolerance.
Since greatly reducing the fat and protein content of her diet, Tracy has had significant amelioration of all of the above symptoms. You can read more of her account on her blog, The Food Way.
As a result of these experiences I have abandoned meat-based “paleo” dieting as popularly conceived, and realized that all my difficulties were predicted by Chinese medical nutrition theory, which has a few thousand years head start on recent "paleo" diet theory. I have returned to eating a whole food, high-starch, gluten-free, low-fat (≤20% energy as fat) plant-based diet with much smaller amounts of animal products, primarily fish and shellfish. Although this accords with both traditional Chinese medical knowledge and modern Western nutrition research, it does not fit with the claim that “paleo diet” consists of a meat-dominated, low-to-moderate carbohydrate, grain-free diet.
[Update 3/20/12: So many people attack me for my supposedly stupid belief that a paleo diet is meat-based and low in carbohydrates. I don't get it. Loren Cordain has gone to great pains to provide evidence that both recent hunter-gatherer and ancient paleolithic era diets were low in carbohydrates. His books and those of Art DeVany and Robb Wolf all present paleo diet as reduced carbohydrate diets with limited starches.
The folks at the Journal of Evolution and Health recently got all excited by this 2011 paper by Ben-Dor et al which argues that man is an evolved fat hunter and includes the following claims
"modern hunter-gatherer (HG) groups, despite having access to fire and metal tools, also seem to have a strong preference for carnivorous foods over vegetal foods ([53]:682), a notion also supported by a recent study [75] that emphasizes limited consumption of carbohydrates by present day HG groups."
"an analysis of nine HG groups for which detailed dietary information exists ([76]:166) shows that five groups, located in an area abundant in vegetation, consumed only a meager amount of plant foods (17% of calories on average)."
I see no indication that scientists promoting paleo diet are endorsing high carb, low fat, low meat diets. I don't base my idea of paleo diet on what bloggers write, I base it on what the advocates of it have written in peer-reviewed science journals.]
Although I now believe that reverse engineering from presently observable human biochemistry and physiology suggests that modern humans are adapted to a high-carbohydrate, low-fat diet with relatively low or intermittent intake of animal foods (by current Western and especially "paleo diet" standards), mostly of fish and shellfish, I doubt that my input will change the now entrenched idea that human evolutionary “paleo” diets were meat- and fat- rich and plant-food poor. Therefore, I will not even attempt to call what I do or advocate a “paleo” or “primal” diet, although I think it appropriate to do so.
But for now I won’t be changing the name of my blog. From the beginning I defined “Primal Wisdom” as the innate intelligence of the bodymind, written in its various nutritional and other requirements, as well as in all the movements of Nature, which inform the Chinese scientific principle of yin-yang complementary opposition. Apparently the Nobel Prize winning physicist Niels Bohr understood the importance of this scientific principle, since he chose the yin-yang symbol for the his coat of arms.
Coat-of-arms of Niels Bohr. Source: Wikipedia
In future posts, I think I will further discuss how we apply this and other Chinese medical principles to nutrition in such a way that makes sense out of the confusing mass of nutrition information available both within scientific research and in practical experience.
Hence, my farewell to popularized paleo. I hope all “paleo,” “primal,” and “hunter-gatherer” dieters fare well in their quest for health. So long as what you do continues to work for you, keep doing it. I hope that you have the knowledge, clarity of mind, and subtlety of awareness to notice the early signs of malfunction before you succumb to something serious and beyond repair. I have a series of blogs forthcoming on this topic, outlining the Oriental medical understanding of the progression of disease from minor to major, which Chinese physicians have used for millenia to help people reverse and prevent diet-related diseases.
