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 (:682), a notion also supported by a recent study  that emphasizes limited consumption of carbohydrates by present day HG groups.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.)
"Indeed, an analysis of nine HG groups for which detailed dietary information exists (: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]
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: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.
If an argument to authority cannot pass these five tests, then it commits the fallacy of appeal to misleading authority.
- 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.
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).
A strong theory of evolution of human diet would be able to explain why vegetarian diets are associated with a lower risk of heart disease than omnivorous diets (as another of many possible examples see this), why vegetarians have a lower body mass index than omnivores, why an essentially vegan soy- and gluten-rich diet reduces cholesterol as effectively as a statin drug, and why eating red meat increases the risk of all cause mortality. Instead of providing an explanation for these painstakingly established scientific findings, some supporters of the hypothesis that humans evolved as carnivores spend their time trying to explain them away because they don't fit their hypothesis. This is not science, it is anti-science. A scientist molds his hypotheses to accommodate the facts, not the other way around.
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.