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“To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact”
~ Charles Darwin (it's evolutionary baybeee!)

Tuesday, May 26, 2015

Thoughts on the Origins of the Paleo Diet

In 1985, S. Boyd Eaton and Melvin J. Konner wrote a seminal paper, in the New England Journal of Medicine, that would "start it all" for the modern paleo diet:  Paleolithic Nutrition: A Consideration of its Nature and Current Implications.  Also that year, they would publish, along with Konner's late wife Marjorie Shostak, The Paleolithic Prescription.  [Some links:  Links to full texts of many paleo papers are here, I discussed the book here.]   Unfortunately the PDF is not digitized so I can't quote here, so I've simply screenshot the introduction below.  If you need to enlarge to read, click on the image and do your thing with the browser!  


What I noticed, the very first time I read this, was not the genetic disconnect/mismatch that is posited later in the paper, but the time line disconnect!  I'm sure I've said this many times before, but I simply have never understood how to correct relatively modern problems, we need to go back to before the age of agriculture for answers!  As Eaton and Konner clearly state, these are problems that have developed in the past century in so-called Western nations and nations that have become increasingly "Westernized".  They have certainly escalated over the past 30-40 years or so, beginning not long before their paper was written.  Again, why not look to what was different in the late 1800's vs. the late 1900's? Or even the early 1900's vs. the late?  Or, quite frankly, during my childhood in the 1960's compared to now?  

But the timeline gaps do not stop there.

In 2000,  Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets  (Cordain, Brand Miller, Eaton, N.Mann, Holt, Speth) was published.
We analyzed the economic subsistence data for all 229 hunter-gatherer societies using all 3 subsistence categories (gathered plant foods, hunted animal foods, and fished animal foods) contained within the updated and revised version of the Ethnographic Atlas (19)
This atlas was the work of anthropologist George Murdock, and I think the following description is apt to include as it touches on a theme of this post:
Starting in 1925, and for 35 years Dr. Murdock was firstly a Professor and later Chairman of the Anthropology Department at Yale University. After 1960 he moved to occupy the Andrew Mellon Chair of Anthropology at the University of Pittsburg for another 15 years until retirement. He founded the journal Ethnology, the Human Relations Area Files and the Society for Cross-Cultural Research, all of which continue to this day.
Murdock established himself as an empiricist emphasizing the methodology of global cross-cultural comparisons, extracting data from numerous cultures around the world which could then be contrasted against each other for the testing of hypotheses. His early and formative work in this direction developed during the period of World War II, when National Character Studies -- an effort to try and understand the cultural conditions which led to German and Japanese militarism -- were understandably at their height of interest.
The Murdock data were originally and sequentially published in the first 22 issues of Ethnology, from 1962 through 1967, allowing peer-review of the data. A full compilation was subsequently published in a single book, the Ethnographic Atlas, which was composed of raw data tables identifying around 50 different cultural traits for a collection of 1170 different cultures. Over decades Murdock had personally studied the published literature of hundreds of other anthropologists. From his readings and also based upon his own extensive field work, and with help from his associates, specific cultural characteristics were identified and coded alpha-numerically for a great number of cultures world-wide, allowing easy cross-cultural comparisons and correlation studies using mathematical approaches. Ethnology continued to publish data on several dozen additional cultures after 1967
Of particular note, the dates.  Some of this data was from field work conducted after 1925 and perhaps on through the 60's, some of it was gleaned from the studies of others -- the "written accounts".  Now I've been doing a lot of reading up on various cultures, and I find it difficult to believe that any sort of quantitative data could be gleaned from some coded tables on subsistence patterns.  Later works apparently took the plant and animal life likely available to various of these cultures into account.  However, even if this could be established to any fair degree of accuracy, there are various "high profile" examples of cultures that do not avail themselves of all possible food sources in their environment, including tribes living in close proximities to one another with dramatically differing diets.  I think the following is one of my all time favorite statements about THE paleo diet.  Writing in Scientific American, Ferris Jabr wonders:
If we compare the diets of so-called modern hunter-gatherers, however, we see just how difficult it is to find meaningful commonalities and extract useful dietary guidelines from their disparate lives (see infographic). Which hunter–gatherer tribe are we supposed to mimic, exactly? How do we reconcile the Inuit diet—mostly the flesh of sea mammals—with the more varied plant and land animal diet of the Hadza or !Kung? Chucking the many different hunter–gather diets into a blender to come up with some kind of quintessential smoothie is a little ridiculous.
I think it best, in order to avoid "wall of text" here, to list a number of issues with information collected from these "so-called modern hunter-gatherers".  In no particular order, and by all means not intended to be an all-inclusive list, I'll attempt to address as many as I can think of that might be gleaned from the totality of the literature:
  1. In regards to dietary classifactions themselves, these categories of plant, land animal and marine-life seem absurdly broad from which to draw conclusions.  Fish in Alaska are different from fish in Africa.  Coconuts differ from acorns differ from grains differ from vegetation, yet all are "plant".   Birds differ from ruminants differ from lizards yet all are "animal".  
  2. There is no "standard template" of the type and extent of data gathered.  I have a few studies with detailed accountings for the types and amounts of food consumed along with a nutritional analysis (done in a lab) and breakdown of the diet in terms of caloric consumption and macronutrient breakdown.  I have several others where it is simply stated weight proportions of foods with no attempt to quantify the energy proportions, and still others that don't quantify at all and just list foods commonly consumed
  3. How many of these "modern" tribes are still truly hunter-gatherers when their diets were assessed?  Can this be assessed from this Atlas and/or was this verified independently or through reference checking?  As you can see in the infographic above, dairy -- which is neither hunted nor gathered (nor paleolithic!) -- is included in the !Kung diet.  Many Native American tribes I've seen described as hunter-gatherers have been described as agriculturalists in other literature.  
  4. By the time of most of these observations, even most remote tribes had been in "contact" for years, decades, and even centuries prior.  Furthermore, they may have had contact with more than one "outside" culture as evidenced by (but limited to) various European countries' influence in colonial territories.
  5. Nomadic peoples may not be occupying the same region as they did even 50 years before let alone thousands of years prior.  There is no more reason to presume that inhabitants of  an area had access to the same types of foods as did those in paleolithic times than there is to presume that the diets of the HG peoples were the same as they would have been.  This is in addition to the known displacement of many HGs from ancestral homelands. 
  6. Even if contact didn't alter the dietary sources much, the means to procure them (horses, weapons, tools), transport them and/or species available may have been helped or hindered by outsider encroachment, trade, and even theft!
  7. Seasonal variations are often obscured.  Seasons don't average well and to do so can result in failure to acknowledge regular changes in diet, and/or a balancing out of perhaps a less healthy diet in one season with a more healthy one the next.  There also seems to be a distinct desire to ignore the role of food preservation and storage, as if squirrels in my back yard are given more credit than our forebearers.  This "oversight" seems to always go against the "inferior" carbohydrate foods which tend to keep the best, and leaves one wondering as to why.
  8. Chronic & Long term environmental factors are also ignored.  I'm talking about droughts or waves of pestilence that may have altered the quantity or quality of available food as well as the non-diet related health of humans.
  9. Overemphasis on hunting vs. gathering, of male health vs. female, of male diets vs. female in the numerous cultures for which there is gender inequity in both activities and consumption (and not necessarily uniformally in favor of one or the other gender).
  10. Even in a single culture, it is often impossible to pin down one "consensus diet".  Some accounts can be in almost direct contradiction, while others vary substantially so as to bring the entire accounting into question.  Which diet prevails to be included when such conflicts exist? 
  11. Since almost all of the literature involves white men and women eventually gaining favor to be allowed to live with these various cultures, there may well be overemphasis on certain aspects of the culture (those they may have perceived would be well received by their guests) while downplaying others (those they may have perceived might offend or repulse them).   Additionally, celebratory foods or foods for guests may well be overrepresented.
  12. Having now read accounts too numerous to count, I cannot go through a list such as this without mentioning how racism enters into almost every accounting.  Whether it be a permeating stink or a tinge of uneasiness, one cannot get away from the facts here.  Most of the observers considered themselves of superior "stock" and the cultures they were observing to be primitive and inferior.  As I'll discuss shortly, this resulted in some grave errors in interpretation due to the hubristic failure to even consider how the invaders may have altered things from their pre-contact state.   
In the end, an ancestral diet is one of inclusion, not exclusion.  Humankind has been eating grains and legumes since before the agricultural revolution, it was called gathering.  We ate sugars and honey and very sweet fruit if it was to be found in the environment.  And yes, we ate meat, and milk, and a lot of foods like insect larvae, stomach contents and blood that are considered gross to the refined modern palate.

Oddly enough, the Paleolithic Prescription was hardly "paleo" by today's standards.  It was scoffed at when Eaton spoke at the Ancestral Health Symposium in 2012.  The most oft tweeted sentiments involved horror at him ingesting shredded wheat and skimmed milk, and anxious queries as to the whereabouts of bacon in his diet.

Nowadays paleo is some sort of template which is then individualized.  Nonsense.  That goes against the very core of its origin.   And yet, there is room for extreme flexibility based on the other facts in evidence.  Humans have been eating plants and animals since well back into the paleolithic.  Including starchy grains and tubers and sugary fruits.  It all depended on what was available to the humans living in a particular environment.

I think on some level the internet marketeers recognize that the paleo fad is fading, and that the once catchy catch-all phrase lost its meaning long ago.  When you cannot define a fad diet consistently, it cannot endure.  The whole draw of fad diets is being given a fixed set of rules and reasons to believe them.  Paleo started out that way with Cordain.  But Cordain's dietary rules and restrictions are unsustainable for most, and unsubstantiated by scientific evidence at almost every turn.

On to "real food"  ....

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