Beyond Ötzi: European Evolutionary History and its Relevance to Diet. Part II

In previous posts, I described how Otzi was (at least in large part) a genetic descendant of Middle Eastern agriculturalists, rather than being purely descended from local hunter-gatherers who adopted agriculture in situ.  I also reviewed evidence showing that modern Europeans are a genetic mixture of local European hunter-gatherers, incoming agricultural populations from the Middle East, neanderthals, and perhaps other groups.  In this post, I'll describe the evidence for rapid human evolution since the end of the Paleolithic period, and research indicating that some of these changes are adaptations to the Neolithic (agricultural/horticultural/pastoral) diet.

Humans have Evolved Significantly Since the End of the Paleolithic

Evolution by natural selection leaves a distinct signature in the genome, and geneticists can detect this signature tens of thousands of years after the fact by comparing many genomes to one another.  A landmark paper published in 2007 by Dr. John Hawks and colleagues showed that humans have been undergoing "extraordinarily rapid recent genetic evolution" over the last 40,000 years (1).  Furthermore:
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Beyond Ötzi: European Evolutionary History and its Relevance to Diet. Part I

In the previous post, I explained that Otzi descended in large part from early adopters of agriculture in the Middle East or nearby.  What I'll explain in further posts is that Otzi was not a genetic anomaly: he was part of a wave of agricultural migrants that washed over Europe thousands of years ago, spreading their genes throughout.  Not only that, Otzi represents a halfway point in the evolutionary process that transformed Paleolithic humans into modern humans.

Did Agriculture in Europe Spread by Cultural Transmission or by Population Replacement?

There's a long-standing debate in the anthropology community over how agriculture spread throughout Europe.  One camp proposes that agriculture spread by a cultural route, and that European hunter-gatherers simply settled down and began planting grains.  The other camp suggests that European hunter-gatherers were replaced (totally or partially) by waves of agriculturalist immigrants from the Middle East that were culturally and genetically better adapted to the agricultural diet and lifestyle.  These are two extreme positions, and I think almost everyone would agree at this point that the truth lies somewhere in between: modern Europeans are a mix of genetic lineages, some of which originate from the earliest Middle Eastern agriculturalists who expanded into Europe, and some of which originate from indigenous hunter-gatherer groups including a small contribution from neanderthals.  We know that modern-day Europeans are not simply Paleolithic mammoth eaters who reluctantly settled down and began farming. 

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Lessons From Ötzi, the Tyrolean Ice Man. Part III

There are two reasons why I chose this time to write about Otzi.  The first is that I've been looking for a good excuse to revisit human evolutionary history, particularly that of Europeans, and what it does and doesn't tell us about the "optimal" human diet.  The second is that Otzi's full genome was sequenced and described in a recent issue of Nature Communications (1).  A "genome" is the full complement of genes an organism carries.  So what that means is that researchers have sequenced almost all of his genes. 

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An Interview with Dr. C. Vicky Beer, Paleo-friendly MD

As I was preparing my recent article on the Paleo diet (1), I interviewed a local Paleo-friendly MD named C. Vicky Beer.  I was only able to include a snippet of the interview in the article, but I thought WHS readers would be interested to read the rest of the interview with Dr. Beer:

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Paleo Diet Article in Sound Consumer

I recently wrote an article for my local natural foods grocery store, PCC, about the "Paleolithic" diet.  You can read it online here.  I explain the basic rationale for Paleo diets, some of the scientific support behind it, and how it can be helpful for people with certain health problems.  I focused in particular on the research of Dr. Staffan Lindeberg at the University of Lund, who has studied non-industrial populations using modern medical techniques and also conducted clinical diet trials using the Paleo diet.
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What Causes Insulin Resistance? Part VII

In previous posts, I outlined the factors I'm aware of that can contribute to insulin resistance.  In this post, first I'll list the factors, then I'll provide my opinion of effective strategies for preventing and potentially reversing insulin resistance.

The factors

These are the factors I'm aware of that can contribute to insulin resistance, listed in approximate order of importance.  I could be quite wrong about the order-- this is just my best guess. Many of these factors are intertwined with one another. 
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Three Announcements

Chris Highcock of the blog Conditioning Research just published a book called Hillfit, which is a conditioning book targeted at hikers/backpackers.  He uses his knowledge and experience in hiking and conditioning to argue that strength training is an important part of conditioning for hiking.  I'm also a hiker/backpacker myself here in the rugged and beautiful Pacific Northwest, and I also find that strength training helps with climbing big hills, and walking farther and more easily with a lower risk of injury.

Richard Nikoley of the blog Free the Animal has also published a book called Free the Animal: Beyond the Blog, where he shares his strategies for losing fat and improving health and fitness.  I haven't had a chance to read it yet, but Richard has a reasonable perspective on diet/health and a sharp wit. 

Also, my friend Pedro Bastos has asked me to announce a one-day seminar at the University of Lisbon (Portugal) by Dr. Frits Muskiet titled "Vitamins and Minerals: A Scientific, Modern, Evolutionary and Global View".  It will be on Sunday, Feb 5-- you can find more details about the seminar here.  Dr. Muskiet is a researcher at the Groningen University Medical Center in the Netherlands.  He studies the impact of nutrients, particularly fatty acids, on health, from an evolutionary perspective.  Wish I could attend. 

Two Recent Papers by Matt Metzgar

This is just a quick post to highlight two recent papers by the economist and fellow health writer Matt Metzgar.

The first paper is titled "The Feasibility of a Paleolithic Diet for Low-income Consumers", and is co-authored by Dr. Todd C. Rideout, Maelan Fontes-Villalba, and Dr. Remko S. Kuipers (1).  They found that a Paleolithic-type diet that meets all micronutrient requirements except calcium (which probably has an unnecessarily high RDA) costs slightly more money than a non-Paleolithic diet that fulfills the same requirements, but both are possible on a tight budget. 

The second paper is titled "Externalities From Grain Consumption: a Survey", with Matt Metzgar as the sole author (2).  He reviews certain positive and negative externalities due to the effects of grain consumption on health.  The take-home message is that refined grains are unhealthy and therefore costly to society, whole grains are better, but grains in general have certain healthcare-related economic costs that are difficult to deny, such as celiac disease.

There are a lot of ideas floating around on the blogosphere, some good and others questionable.  Composing a manuscript and submitting it to a reputable scientific journal is a good way to demonstrate that your idea holds water, and it's also a good way to communicate it to the scientific community.  The peer review process isn't perfect but it does encourage scientific rigor.  I think Metzgar is a good example of someone who has successfully put his ideas through this process.  Pedro Bastos, who also spoke at the Ancestral Health Symposium, is another example (3).

Food Reward: a Dominant Factor in Obesity, Part III

Low-Fat Diets

In 2000, the International Journal of Obesity published a nice review article of low-fat diet trials.  It included data from 16 controlled trials lasting from 2-12 months and enrolling 1,910 participants (1).  What sets this review apart is it only covered studies that did not include instructions to restrict calorie intake (ad libitum diets).  On average, low-fat dieters reduced their fat intake from 37.7 to 27.5 percent of calories.  Here's what they found:
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New Ancestral Diet Review Paper

Pedro Carrera-Bastos and his colleagues Maelan Fontes-Villalba, James H. O'Keefe, Staffan Lindeberg and Loren Cordain have published an excellent new review article titled "The Western Diet and Lifestyle and Diseases of Civilization" (1). The paper reviews the health consequences of transitioning from a traditional to a modern Western diet and lifestyle. Pedro is a knowledgeable and tireless advocate of ancestral, primarily paleolithic-style nutrition, and it has been my privilege to correspond with him regularly. His new paper is the best review of the underlying causes of the "diseases of civilization" that I've encountered. Here's the abstract:

It is increasingly recognized that certain fundamental changes in diet and lifestyle that occurred after the Neolithic Revolution, and especially after the Industrial Revolution and the Modern Age, are too recent, on an evolutionary time scale, for the human genome to have completely adapted. This mismatch between our ancient physiology and the western diet and lifestyle underlies many so-called diseases of civilization, including coronary heart disease, obesity, hypertension, type 2 diabetes, epithelial cell cancers, autoimmune disease, and osteoporosis, which are rare or virtually absent in hunter–gatherers and other non-westernized populations. It is therefore proposed that the adoption of diet and lifestyle that mimic the beneficial characteristics of the preagricultural environment is an effective strategy to reduce the risk of chronic degenerative diseases.

At 343 references, the paper is an excellent resource for anyone with an academic interest in ancestral health, and in that sense it reminds me of Staffan Lindeberg's book Food and Western Disease. One of the things I like most about the paper is that it acknowledges the significant genetic adaptation to agriculture and pastoralism that has occurred in populations that have been practicing it for thousands of years. It hypothesizes that the main detrimental change was not the adoption of agriculture, but the more recent industrialization of the food system. I agree.

I gave Pedro my comments on the manuscript as he was editing it, and he was kind enough to include me in the acknowledgments.

Paleolithic Diet Clinical Trials, Part V

Dr. Staffan Lindeberg's group has published a new paleolithic diet paper in the journal Nutrition and Metabolism, titled "A Paleolithic Diet is More Satiating per Calorie than a Mediterranean-like Diet in Individuals with Ischemic Heart Disease" (1).

The data in this paper are from the same intervention as his group's 2007 paper in Diabetologia (2). To review the results of this paper, 12 weeks of a Paleolithic-style diet caused impressive fat loss and improvement in glucose tolerance, compared to 12 weeks of a Mediterranean-style diet, in volunteers with pre-diabetes or diabetes and ischemic heart disease. Participants who started off with diabetes ended up without it. A Paleolithic diet excludes grains, dairy, legumes and any other category of food that was not a major human food source prior to agriculture. I commented on this study a while back (3, 4).

One of the most intriguing findings in his 2007 study was the low calorie intake of the Paleolithic group. Despite receiving no instruction to reduce calorie intake, the Paleolithic group only ate 1,388 calories per day, compared to 1,823 calories per day for the Mediterranean group*. That's a remarkably low ad libitum calorie intake in the former (and a fairly low intake in the latter as well).

With such a low calorie intake over 12 weeks, you might think the Paleolithic group was starving. Fortunately, the authors had the foresight to measure satiety, or fullness, in both groups during the intervention. They found that satiety was almost identical in the two groups, despite the 24% lower calorie intake of the Paleolithic group. In other words, the Paleolithic group was just as full as the Mediterranean group, despite a considerably lower intake of calories. This implies to me that the body fat "set point" decreased, allowing a reduced calorie intake while body fat stores were burned to make up the calorie deficit. I suspect it also decreased somewhat in the Mediterranean group, although we can't know for sure because we don't have baseline satiety data for comparison.

There are a few possible explanations for this result. The first is that the Paleolithic group was eating more protein, a highly satiating macronutrient. However, given the fact that absolute protein intake was scarcely different between groups, I think this is unlikely to explain the reduced calorie intake.

A second possibility is that certain potentially damaging Neolithic foods (e.g., wheat and refined sugar) interfere with leptin signaling**, and removing them lowers fat mass by allowing leptin to function correctly. Dr. Lindeberg and colleagues authored a hypothesis paper on this topic in 2005 (5).

A third possibility is that a major dietary change of any kind lowers the body fat setpoint and reduces calorie intake for a certain period of time. In support of this hypothesis, both low-carbohydrate and low-fat diet trials show that overweight people spontaneously eat fewer calories when instructed to modify their diets in either direction (6, 7). More extreme changes may cause a larger decrease in calorie intake and fat mass, as evidenced by the results of low-fat vegan diet trials (8, 9). Chris Voigt's potato diet also falls into this category (10, 11). I think there may be something about changing food-related sensory cues that alters the defended level of fat mass. A similar idea is the basis of Seth Roberts' book The Shangri-La Diet.

If I had to guess, I would think the second and third possibilities contributed to the finding that Paleolithic dieters lost more fat without feeling hungry over the 12 week diet period.


*Intakes were determined using 4-day weighed food records.

**Leptin is a hormone produced by body fat that reduces food intake and increases energy expenditure by acting in the brain. The more fat a person carries, the more leptin they produce, and hypothetically this should keep body fat in a narrow window by this form of "negative feedback". Clearly, that's not the whole story, otherwise obesity wouldn't exist. A leading hypothesis is that resistance to the hormone leptin causes this feedback loop to defend a higher level of fat mass.