Hunter-Gatherers and Health - Part 4

The *Real* Paleo Diet

Last time we looked at the Paleo Diet® and saw that it is actually a misnomer. It was based on people eating wild food resources and maintaining traditional ways of life outside the confines of modern industrial civilizations. However, the diets and lifestyles of modern-day hunter-gatherers are vastly different than what they would have been during the actual Paleolithic era.

To help us understand why, let's take a quick trip through paleontology.

The term "Paleolithic" doesn't refer to food or diet at all—it refers to tool use. It means "old stone age" and lasted for over three million years, from the first stone tool use in our remote ancestors until the development of the first settled villages and farming around 10,000 years ago.

The Paleolithic era almost perfectly coincided with a climatic regime known as the Pleistocene, which was characterized by extreme temperature swings known as glacials and interglacials where the polar ice sheets repeatedly advanced and retreated. This is informally known as the Ice Age. The peak of the last Ice Age, known as the Last Glacial Maximum, occurred between roughly 26,000 and 13,000 years ago.

After the Last Glacial Maximum ended, the earth’s climate settled into a more stable climatic regime known as the Holocene after around 12,000 years ago. All of human civilization has unfolded during this period.

The world of the Holocene was radically different from the several million years which preceded it. During the Pleistocene the earth was full of gigantic animals over a ton in weight collectively known as megafauna. These fantastic beasts included ground sloths as big as elephants, armadillos the size of hippos, beavers the size of black bears, rodents the size of cows, the wild ancestors of today's cattle (aurochs), sabretooth cats (smilodon), and multiple species of elephantoids such as woolly mammoths and mastodons. Woolly rhinos, European bison, cave lions and hyenas roamed what is today Northern Europe. Herds of wild horses, camels and cheetahs lived in what is today North America. Animals generally were much bigger back then, and many of them were depicted on cave paintings; for example, the Irish Elk below (which was actually a giant deer, and not related to modern elks):

What would eventually become the major cities of Europe and North America lay under a mile-thick sheet of ice. Places like the Sahara and the Arabian peninsula were lush grasslands rather than windswept deserts, and Europe was comprised of forests and tundra, with a boreal climate allowing reindeer to migrate as far south as France and Spain. The ocean level was 200 feet lower because of all the water locked up in ice sheets, meaning that continental shelves which are submerged today were dry land. The number of humans on the entire planet was less than the number of people who pass through Heathrow airport on any given day.

Because the Paleolithic was such an extremely long time span, archaeologists generally subdivide it into Lower, Middle and Upper. The Lower Paleolithic saw the emergence of the earliest stone tools and the birth of Homo erectus (upright-walking man), the first species to look something like us. Armed with their Acheulian toolkit—especially the hand-axe—and probably utilizing fire as well, they were the first hominid to spread out all over the earth (except for the Americas and Australia), evolving into several different species along the way. The exact process by which this occurred is something of a mystery—there is a dearth of fossil evidence after one million years ago.

Around 200,000 years ago we enter the Middle Paleolithic era, dominated by three major groups of archaic humans: Neanderthals in Europe and western Asia; a group of species known collectively as the Denisovans in eastern and southeastern Asia; and Homo sapiens (our direct ancestors) confined mostly to Africa with a few scattered populations here and there in the Levant. At this time there were still isolated pockets of erectus living in remote places like Indonesia, as well as other hominids like the recently discovered Homo luzonensis in the Philippines and Homo longhi in China.¹

The Upper Paleolithic began around 45-50,000 years ago. The most notable feature of this era is the disappearance of the Pleistocene megafauna. During this time, anatomically modern Homo sapiens spread out and colonized every nook and cranny of the globe, including Australia, the Americas, and even remote Pacific islands, becoming perhaps the most successful invasive species of all time. As far as we know, all humans alive today are descended from a population that originally left Africa between 50-70,000 years ago, possibly originating in the southern part of the continent. As they spread out, they interbred with various groups of archaic humans they encountered whose DNA lives on in us today. Eventually those other hominid species died out leaving us the sole representative of humans on earth after around 25,000 years ago during the peak of the last Ice Age.

Because the climate fluctuated so drastically during the Pleistocene, one of the main features selected for in our evolution was behavioral flexibility. The ability to adapt to rapidly changing circumstances was what differentiated the successful hominid species that eventually led to us from those who were left behind only as skulls for us to dig up later.

This flexibility and adaptability, however, makes it hard for us to specify exactly what the human lifestyle and diet would have been like during the Paleolithic era such a very long time ago. Nonetheless, we can look to paleontology, archaeology, and—perhaps most importantly—human anatomy and physiology—to give us some answers.

The Real Paleo Diet

That was the approach taken by a cross-disciplinary team of scientists and researchers in a paper published in The American Journal of Physical Anthropology in 2021. This was, of course, too late to be included in either Burn or Exercised.

The evolution of the human trophic level during the Pleistocene (Wiley)

The paper attempted to determine the human trophic level (HTL) during the Paleolithic, which is a fancy way of saying where humans sat on the food chain. It surveyed experts from a wide range of fields including 1.) anatomy & physiology; 2.) archaeology; 3.) paleontology; 4.) zoology; and 5.) anthropology & ethnography. The study was the largest and most comprehensive of its kind, examining over 400 scientific papers and taking ten years to complete.

The authors of the paper make the same point as I did above: modern-day hunter-gatherers are a poor stand-in for how our ancestors lived during the Paleolithic era thanks to things like climate change, extensive environmental modification and widespread species extinction. As they put it,

"This comparison [between modern HGs and those in the Paleolithic] is futile...because 2 million years ago hunter-gatherer societies could hunt and consume elephants and other large animals—while today's hunter gatherers do not have access to such bounty...The entire ecosystem has changed, and conditions cannot be compared..."

Instead, the researchers looked to human anatomy and physiology for evidence; as they put it, "Human behavior changes rapidly, but evolution is slow. The body remembers." They combined this approach with evidence with from archaeology and paleontology such as bones and stone tools, as well as ethnographic studies of present-day hunter-gatherers.

The paper acknowledges that humans are omnivores who can eat a wide variety of both plants and animals, but it points out that most omnivores typically specialize in obtaining either plants or animals rather than preferring equal amounts of both: "For example, both chimpanzees and wolves are technically omnivores yet are ill-adapted to high flexibility in their food sources." They compiled a list of twenty-five data points to make their assessment, assigning them to different categories—either plant specialists, specialized carnivores or generalized omnivores.

Some of these points we've already covered. Humans have a faster metabolism than other great apes. We have an unusually large and energy-hungry brain. We are much more physically active than other great ape species, with a significantly higher PAL ratio. Our bodies store greater amounts of fat than other apes in order to cope with the energetic demands of our physically active lifestyles and large brains. We live longer past our reproductive years than other apes and our infants are weaned later.

In addition to those facts, among the additional evidence the researchers compiled include the following:

• Our body appears to be adapted to occasional fasting to cope with the intermittent appearance of large prey animals. We are able to quickly shift to burning ketones to fuel our brain, which is a feature not shared by other omnivores or herbivores.

• Our anatomy and physiology is optimized toward running long distances after animals and hurling projectiles at them rather than climbing in trees or foraging for plants: "It's a general rule of ecology that plant-eaters don't travel far each day, because plants are plentiful and don't run away. Living apes rarely cover more than a mile or two in a given day." (B: 127-128) Our bodies appear to be adapted for endurance running, and we are the best endurance runners in the animal kingdom despite our obvious lack of strength and speed.

• The guts of plant-eating omnivores like chimpanzees and gorillas are much larger than ours because it takes more energy to extract nutrients from fibrous vegetable matter than from energy-dense meat and fat.

• Our teeth and jaws are not designed for chewing tough, reedy plant foods unlike those of our closest relatives such as chimpanzees, bonobos and gorillas, and even our earliest ancestors like Australopithecus.

• The acidity of our stomach is much higher than omnivores and even many carnivores. High acidity is metabolically expensive indicating that old and/or scavenged meat must have been a significant part of our diet for a long time.

• In omnivores and herbivores, fat is stored in a relatively small number of large fat cells. Humans have smaller, more numerous fat cells, similar to other carnivores.

• Geneticists have concluded that areas of the human genome were closed off to enable a fat-rich diet, while in chimpanzees, areas of the genome were opened to enable a sugar-rich diet. We metabolize fat more easily than sugars and starches.

• Humans, like other carnivores, have a low (non-pathological) insulin sensitivity.

• Analysis of stable isotopes found in the collagen of fossil bones has shown that human consumption of meat was more in line with specialized predators like wolves rather than generalized omnivores like pigs or bears. This site from Australia describes this method:

Teeth and bones contain a protein called collagen, which absorbs chemical elements such as nitrogen, carbon, calcium and strontium from the food that an individual eats. Different types of foods contain these elements in different ratios so scientists are able to obtain information about our ancestors’ diets by studying the chemical elements found in fossilised bones and teeth. The ratios of these various elements are then compared with those of various modern-day animals to establish the types of foods eaten by our ancestors.

Based on analysis of stable isotopes, the researchers estimate that the diet of hominids in the Lower and Middle Paleolithic periods consisted of somewhere in the neighborhood of 70 to 80 percent animal sources.

• Carnivorous species are the most widespread species because hunting prey is not a highly specialized activity. Herbivores, on the other hand, tend to be much more limited to specific ecologies because plants boast many physical and chemical defenses that require specific adaptations. Humans and wolves are the most widely-distributed mammalian species, and wolves are specialized carnivores.

• Fatter animals appear to have been preferentially targeted by Paleolithic hunters at high energetic costs, and fat is a highly-prized food in most hunter-gatherer cultures today, even those that get nearly all of their calories from plants.

• Hunting requires a great deal of skill, which takes years to master. Peak productivity for most hunters occurs around age 40, and longer lifespans may indicate the importance of bagging large prey animals in the diet, as well as the importance of cultural transmission to accomplish it.

• Bones at butchering sites indicate that humans' favored prey was often quite large. Even whales—the planet's largest animal—have been hunted by humans. Generalized omnivores do not, as a rule, go after prey much bigger than them, whereas specialized carnivores do. Omnivores who go after such large prey are typically hypercarnivores, obtaining at least 70 percent of their calories from meat. As one researcher put it, "Hunting large animals is not an afternoon hobby."

• Stone toolkits used to hunt and butcher animals remained essentially the same for hundreds of thousands of years all over the world. Tools and equipment to process plant foods, on the other hand, appear fairly late in the archaeological record. Only during the Upper Paleolithic do we start to see stone toolkits becoming highly differentiated and specialized in order to process a wider variety of food types.

• Dental caries (cavities) become much more prevalent at the same time as people started switching to a starchier diet around 15,000 years ago. Before then cavities were very rare (under 2 percent), indicating our teeth are not adapted for such a diet. Tooth decay becomes even more prevalent after the Neolithic Revolution when people start consuming starchy carbohydrates on a regular basis. Note that no dentist has ever told us to prevent cavities by cutting back on our meat consumption.

Based on the majority of data points they collected, the researchers concluded that for the last several million years humans were apex predators specializing in the hunting of large prey animals, and only during the Upper Paleolithic and thereafter did humans start eating lower down the food chain out of necessity.

In assessing the archaeological evidence, the paper acknowledges that telltale signs of meat consumption like stone spear points and bones from carcasses tend to be preserved while plant foods and associated processing equipment (like wooden digging sticks) are not. The paper notes that humans definitely ate plant foods during the Paleolithic—that is beyond any doubt. However, they argue that the evidence indicates that hunting animals played the predominant role in getting calories for most of the Paleolithic. As they write, "Archaeological evidence does not overlook the fact that stone-age humans also consumed plants...but according to the findings of this study plants only became a major component of the human diet toward the end of the [Paleolithic] era."

Evidence of Paleolithic plant eating is cited by Dr. Pontzer in his "debunking" of the Paleo Diet:

...it's a common misperception among many in the Paleo crowd that our hunter-gatherer ancestors were somehow only hunting. Perhaps this view reflects the inherent biases in fossil and archaeological record [sic]. Bones preserve much better than plant foods, as do the tools used to hunt. Hunting technologies often involved stone flakes or points, which don't rot or degrade. As we see with the Hadza, collecting plant foods requires nothing more than strong hands and a wooden stick. Direct evidence for eating plants isn't as readily available in the archaeological and fossil record, but all signs point to a balanced diet similar to that of living hunter-gatherers.

Some of the newest and most exciting research on hominin diets comes from analyses of food particles trapped in the plaque stuck to the teeth of fossil hominins. Amanda Henry at Leiden University is a pioneer in the burgeoning subfield of human evolution. She and her colleagues have carefully extracted the dental calculus (calcified plaque) from the teeth of Neanderthals at fossil sites across Europe and into the Near East.

Under a microscope, she found grains and starches from plant foods in nearly every sample, despite the fact that she was looking at mere milligrams of material. Neanderthals were the quintessential big-game hunters, but they balanced all that meat with carb-rich grains, starchy tubers, sweet fruits and nuts. Henry has found similar evidence in the fossilized teeth of members of our own species from this period. Our Paleolithic ancestors would no doubt be amused by the widespread notion in today's Paleo diet circles that grains and starchy carb-rich plant foods were off the menu. (B: 196-197)

Of Amanda Henry's (and others’) work cited by Pontzer, the authors of the paper note (emphasis mine):

The assemblage of cases suggests that consumption of plants was common, although one has to take into account that the consumption of starch encourages dental plaque formation and that we do not know the percentage of teeth that were not sampled because they had no calculus. But even if we had these data, the identification of plants in dental calculus cannot tell us what the relative plant consumption of the individual was. However, we can summarize that the archaeological and ethnographic record shows that plant foods were a frequent component of the Paleolithic diet.

But this is only a refutation if you are arguing that people in the Paleolithic ate nothing but meat! As far as I'm aware, nobody clams that except perhaps some fringe writers and internet bloggers (even advocates of so-called "carnivore" diets do not claim that it's based on any kind of archeological evidence as far as I'm aware).

The authors of the paper note that even though there is certainly clear evidence for plant consumption deep into the Paleolithic, there is no way to tell what percentage of the diet was comprised of plant foods relative to animal foods. Despite clear evidence of plant eating, the authors nevertheless claim the preponderance of evidence indicates that humans were hypercarnivores who occupied the apex predator niche rather than omnivores who ate mostly plants supplemented by occasional hunting as some have surmised based on the lifestyles of modern-day hunter-gatherers.

One study looking at the collagen in Neanderthal bones determined that their diet was 80 percent meat and 20 percent plants. Another study indicted that Neanderthals and early humans occupied basically the same ecological niche going after large herbivores. The researchers added, “These new … measurements confirm earlier interpretations of Neanderthal diets as being composed of mainly large herbivores, although of course they also consumed other foods such as plants." A study of the oral bacteria of a 100,000 year-old Neanderthal showed that they were adapted to eating starches:

The biggest surprise from the study was the presence of particular strains of oral bacteria that are specially adapted to break down starch. These strains, which are members of the genus Streptococcus, have a unique ability to capture starch-digesting enzymes from human saliva, which they then use to feed themselves. The genetic machinery the bacteria uses to do this is only active when starch is part of the regular diet. Both the Neanderthals and the ancient humans scientists studied had these starch-adapted strains in their dental plaque while most of the primates had almost no streptococci that could break down starch…

The findings also push back on the idea that Neanderthals were top carnivores, given that the "brain requires glucose as a nutrient source and meat alone is not a sufficient source," Warinner said. Researchers said the finding makes sense because for hunter-gatherer societies around the world, starch-rich foods— underground roots, tubers (like potatoes), and forbs, as well as nuts and seeds, for example—are important and reliable nutrition sources. In fact, starch currently makes up about 60 percent of calories for humans worldwide.

Turns out developing a taste for carbs wasn't a bad thing (Harvard Gazette)

Some of the additional evidence we've already looked at. As Pontzer himself pointed out, many areas of our genome have undergone changes due to pressure from our diets. Most of these changes came about from eating a diet richer in carbohydrates and starches, and lower in fat and animal protein. These changes are very recent (in evolutionary time), and appear to have taken place mostly during the Upper Paleolithic—that is, during the last 40,000 years. If humans were truly omnivores eating primarily plant foods for most of our evolutionary history, such changes would have been unnecessary. The evidence from archaeology backs this up—we didn't start inventing plant processing equipment until our preferred prey animals started disappearing from the scene.

The authors of the paper conclude, therefore, that these shifts in dietary habits were mainly caused by the extinction of large prey animals rather than an instinctual preference for plant foods in the diets of Paleolithic humans. In other words, meat was the main course until roughly the last 40,000 years when we started eating lower down the food chain out of necessity.

This dietary and behavioral flexibility is not a bad thing—many scholars believe it's the reason why we're the last hominid standing. The Holocene led to the extinction of Ice Age megafauna, but it also led to a proliferation of edible plants all over the world. Many of these foods require extensive processing due to their evolved defenses from predators², which only our species was able to accomplish thanks to our big-brained tools and culture. Those same characteristics also gave us the ability to modify ecosystems all over the world in order to suit us (niche construction). The stability of the Holocene also made the deliberate cultivation of our favored plant foods a possibility for the first time³. As one research paper put it, agriculture may have been, "impossible during the Pleistocene but mandatory during the holocene."

Humans may have begun adapting to this change in environment very early in some places. A recent study used zinc isotopes to determine the dietary habits of humans living between 46 and 63,000 years ago in the tropical rain forests of southeast Asia—modern-day Laos. They found that the inhabitants of the rain forest were already adapting their diets to suit local conditions, obtaining a higher proportion of their calories from plant sources than humans living elsewhere in the world at that time.

Humans, then, went through a ‘Z-curve’ of trophic levels. We started out as arboreal vegetarians—prey as well as predators. Eventually, we came down from the trees and started foraging on the ground as well. Those remote ancestors probably ate much the same way as chimps and bonobos do today. Then sometime between three and four million years ago we increasingly started scavenging meat from kills, possibly cutting it loose using the earliest rudimentary stone tools.

Then, sometime around 2.5 million years ago in Africa, the forests started shrinking and grasslands began expanding. We invented hunting and gathering (and sharing). This division of labor allowed us to diversify our diets, getting a greater portion of our calories from actively hunting prey rather than just gathering and scavenging.

Every aspect of our anatomy and physiology was transformed. Our bodies adapted to running, probably for persistence hunting in the heat of the African savanna. We gradually started climbing up the food chain. Our brains became bigger and our guts became smaller. We started living longer and developing shared social learning—i.e. culture.

We also started using fire, allowing us to externally predigest our food, although the exact timing of when this occurred is controversial. One possibility is that we used naturally-occurring fires or volcanic vents to cook our food long before we learned how to make fire ourselves. In fact, there is a major uptick in naturally-occurring fires that occurs right around 2.5 million years ago in Africa due to an exploding supernova.

By one million years ago human ancestors were apex predators specializing in the hunting of large herbivores over a ton in weight. Other unrelated species of hominins were possibly occupying different ecological niches at this time such as Paranthropus.

Then, starting sometime around 50,000 years ago, our particular lineage began spreading outward from Africa like a virus. At the same time, large prey animals started disappearing all over the world (which may have been in large part caused by us).

After 25,000 years ago, the climate started becoming warmer and more hospitable (except for a brief hiccup called the Younger Dryas). We started moving back down the food chain, becoming generalized omnivores once again, getting a larger portion of our calories from plant sources and relatively fewer from animal sources, especially wild ones (excepting fish). Today, gathering plant foods provides the majority of calories for most hunter-gatherers outside of the Arctic (who should really be called gatherer-hunters). Recall that it’s from these groups that virtually all of the Paleo Diet advice actually came from.

With the arrival of the Neolithic Revolution around 10,000 years ago, plants took center stage. By the late Neolithic, the bulk of humanity's nutrition came from, in effect, eating grass seeds, leading to all sorts of health problems and nutritional deficiencies, as forensic anthropologists have long since determined by examining ancient skeletons from farming societies.

Of course, the problems in these societies went beyond just diet. Plants, unlike animals, don't move around, so we took up permanent residence next to them becoming sedentary rather than mobile. This led to sanitation problems—crudely put, hunter-gatherers don't shit where they eat. We encountered a whole new host of epidemic diseases transmitted from our domesticated livestock—called zoonotic diseases. Wild foods to supplement grain consumption were in ever shorter supply as formerly-fertile ecosystems were stripped bare due to overpopulation and monocultures. Overpopulation also led to greater conflict between different groups of people as moving away from prime real estate became less of an option. Meat became a luxury item reserved for the upper classes, while the mass of individuals toiling away in these societies got by on little more than gruel, a few vegetables and weak beer until approximately the last hundred years or so.

Simply put, you can't have seven billion apex predators. You can't even have one billion. There's a reason it's called a trophic pyramid.

The Takeaway

This is sure to be controversial. There is an attempt right now to get people to eat less meat for both environmental and animal welfare reasons. Much of this is bound up with claims that this-or-that diet is the “natural” one for us to eat, whether vegetarian or Paleo. For example, Pontzer describes one extreme version of this approach:

Vegans can be just as militant and annoying [as Paleo Diet evangelists]. When I lived in Brooklyn and spent my mornings and evenings on the subway, a very energetic and upset woman on the F train used to walk through the cars, haranguing passengers and handing out pamphlets explaining how humans are naturally evolved to eat plants. "Look at our teeth!" she'd yell. "Meat rots in our herbivore guts!" She may have been a diet vigilante, but she wasn't alone. Those are talking points from PETA. (B: 194)

But in reality, I don't see any of the above as an indication to eat only meat, or even mostly meat. Environmental and animal welfare reasons are perfectly valid reasons to consume less animal products on their own—you don't need to try and convince people that this-or-that diet is somehow more "natural" on top of it. In fact, making a bunch of pseudoscientific claims like the person above undermines your argument rather than strengthens it.

As we learned last time, humans can be perfectly healthy eating a wide variety of diets, including ones that have a very high proportion of plant foods. It happens to be the case that growing meat can be environmentally destructive, and the way we treat factory-farmed animals is an abomination that we should all be ashamed of. Consider that under our present system, even showing us how our food is produced is literally illegal! (so-called "ag-gag" laws sponsored by the food industry).

You can be perfectly healthy eating a diet consisting of mostly plant foods, or even entirely of plant foods, such as vegetarians or vegans. There are any number of valid reasons for choosing such a diet without claiming an evolutionary mandate for it, or that it is somehow more natural or more healthy. But, like it or not, the idea that we are descended from omnivores who ate mostly—or even exclusively—plants for most of our evolutionary history just doesn't hold up to empirical scrutiny.

And besides, we don't live in the Paleolithic anymore. Lions and elephants don't roam the Midwestern prairie, and herds of wild elk and reindeer don't stalk the suburbs of Paris. Our environments, cultures, habitats, food production methods, lifestyles, genes, and so on, have changed so dramatically and so profoundly since the Ice Age that it's hard to derive any real, practical advice for people living in modern societies based on what our ancestors may or may not have been eating hundreds of thousands of years ago. Our food supply has been irrevocably altered, for better or worse. As the authors of the study themselves note:

None of this is to say we ought to eat more meat. Our evolutionary past isn't an instruction guide on human health, and as the researchers emphasize, our world isn't what it used to be. But knowing where our ancestors sat in the food web has a big impact on understanding everything from our own health and physiology, to our influence over the environment in times gone by.

Humans Were Actually Apex Predators For 2 Million Years, New Study Finds (Science Alert)

But I do think it means that the idea that meat is inherently bad for us doesn't hold up to scrutiny, either. Recall that the food pyramid placed meat and fat close to the top. Meat and fat are the most calorically dense foods, and this led to them being unfairly stigmatized thanks to the prevailing energy balance model (CICO) which, as we've already seen, has all sorts of problems with it. Many of the foods were were told were bad for us—like eggs and dairy—probably aren't. As this article in the Guardian pointedly asks, "Is mother nature a psychopath? Why would she design foods to shorten the lifespan of the human race?"⁴

Perhaps the wholesale demonization of meat in this effort, too, is counterproductive. Maybe it makes more sense to look at where and how those things are produced. Some ecologies are more suited to pastoralism than others—we shouldn't be burning down the Amazon rain forest for beef, after all. Also, these animals are domesticated meaning that they cannot "return to the wild" or survive without us, so unless we exploit them they will go completely extinct, for better or worse. And there are proposals out there like rewilding; the Great Prairie Buffalo Commons; and regenerative agriculture, all of which allow for meat consumption without unspeakable cruelty or environmental devastation. These ideas make a lot more sense than exhorting us all to eat only vegetables, or Silicon Valley-approved substitutes like heavily processed pseudo-meat made from plants, test-tube meat, or powdered cricket protein.

And, to be clear, I'm not pushing the Paleo Diet as "the" diet to follow, or make the case that all of its claims are empirically true. I just felt that a lot of the arguments "debunking" the diet were bogus, inaccurate, or misleading. I feel like a lot of the arguments against the Paleo Diet have a hidden agenda that is not 100 percent on the level (like making processed and artificial foods from the food industry more acceptable). I also think that an ancestral approach to health and nutrition happens to be the right one, and is tremendously beneficial for humans just as it would be for any other animal. And really, even Pontzer agrees with this! For instance, Pontzer et. al. wrote the following in a paper looking at hunter-gatherers as role models for public health (emphasis mine):

The remarkable metabolic and cardiovascular health of hunter-gatherers and other small-scale populations has long made them attractive models in public health. Given the similarity in health profiles across ethnic groups, it is clearly their environments, rather than genetics, that keep people within small-scale societies so healthy. Indeed, from Australia to the Americas, these populations develop the same metabolic and cardiovascular ‘diseases of civilization’ when they move away from traditional lifestyles and adopt Western diets and activity levels...

Diets in hunter-gatherer and other small-scale societies tend to be less energy dense and richer in fibre and micronutrients than modern diets but are not invariably low carbohydrate as sometimes argued...Traditional diets do seem to be more nutrient dense, higher in fibre and lower in glycaemic index than foods in industrialized cultures...A more integrative understanding of hunter-gatherer health and lifestyle, including elements beyond diet and activity, will improve public health efforts in industrialized populations...

Hunter-gatherers as models in public health (Pontzer, Wood, and Raichlen)

In fact, one oft-cited study by Paleo advocates followed ten diabetic, middle-aged, overweight Australian aborigines who went back to their traditional foraging lifestyle. After just seven weeks, they lost a fair bit of weight and their diabetic symptoms improved dramatically.

I do think the Paleo Diet is a pretty decent diet to follow, even if a lot of the reasons it works may not be what its developers claim. I'm skeptical of their claims that grains and legumes are inherently bad for us because of lectins. Traditional peasant diets around the world were often based on these foods, and people didn't get fat or become unhealthy (as long as they had enough to eat).

But eschewing refined and processed grains is probably beneficial for us today. Most bread today is simply empty calories, has a high glycemeic load, and is full of nasty ingredients to prolong shelf life. Plus, eliminating refined carbs like breads and sugar automatically rules out nearly all fast food and ultraprocessed foods that we know for sure are bad for us. More animal protein from natural sources (such as wild-caught or grass-fed) helps keep us feeling full, and we know that eating fruits, nuts, and vegetables is definitely healthy for us. Eschewing dairy products might be throwing out the baby with the bath water (but I'm from Wisconsin, so I would say that).

It may be the case that limiting certain foods has the effect of reducing calorie consumption without having to keep track, and that's the real reason the diet works, rather than what specific kinds of foods are consumed or avoided (which is exactly what the critics argue). If so, it still gets the job done—no caveman outfit or bows-and-arrows required.

There are other options, too. Last time I had to cut out a bunch of stuff on Dr. Weston Price. Price was a dentist who traveled the world in the 1920s and 1930s looking at the diets of people living traditional lifestyles and eating foraged and locally-grown (i.e. non-Western) foods. His conclusions were collected in his magnum opus, Nutrition and Physical Degeneration, published in 1939.

While a lot of his ideas about nutrition and health were dismissed at the time, some of them turned out to be true⁵. His writings launched a dietary movement promoted by the Weston A. Price Foundation, which emphasizes a diet based around traditional whole foods prepared in a customary ways (such as sprouting grains to make them more palatable), and also heavy in meat and fat. Unlike Paleo, it doesn't avoid foods like grains, dairy, and legumes, so long as they are naturally-sourced and prepared in a traditional manner (i.e. no refined or ultraprocessed foods). Like the Paleo Diet, it hews against the "low fat, less meat" imperative pushed by the mainstream nutrition community, hence the polemical, Fox-Newsy subtitle of their cookbook: "The Cookbook that Challenges Politically Correct Nutrition and Diet Dictocrats."

Either approach is bound to be far better than the standard industrialized Western-style diet, however, which is sadly displacing older, healthier, traditional ways of eating all around the world (e.g. Latin America, Asia, etc.) and leading to an epidemic of chronic diseases.

As we've already seen, even though "calories out" is more-or-less fixed despite our activity level, "calories in" is not. It is this fact that Pontzer points to as the prime culprit behind our growing obesity problem, rather than any specific diet or type of food. That's what we'll look at next time.

The Evolution of Diet (National Geographic)

1. Homo longhi might, in fact, be a Denisovan—it seems like the jury is still out.

2. Among these evolved defenses are lectins, a protein produced by cereal grains and legumes (among others). Proponents of the Paleo Diet argue that lectins (not to be confused with leptin) are harmful to us, and are behind a range of gastrointestinal disorders like leaky gut syndrome, irritable bowel syndrome, and Crohn's disease. I don't know enough to adjudicate this, but this argument often gets lost among all the claims and counter-claims of supposed historical and ethnographic accuracy.

3. The climatic stability that made human civilization possible is already gone due to anthropogenic climate change. People tend to focus on warming, but what's just as frightening is the loss of climatic stability—which is a precondition for large-scale agriculture. We're already seeing it wreak havoc and causing all sorts of food shortages all over the world.

4. As the article points out, most of these studies make no distinction between processed meat products and unprocessed meats from muscles, organs, etc. They also do not distinguish between wild and domesticated animals.

5. This is from a fascinating book called Skeletons in Our Closet by bioarchaeologist Clark Spencer Larsen (2000):

“I see other implications for the redutions in skull robusticity brought about by the shift from from foraging to farming in our ancestors. Chief among them is the phenomenal increase in the incidence of malocclusion, tooth crowding, and impaction (especially in the ‘wisdom teeth,’ or the third molars) in people worldwide. This increase has been especially dramatic in the last couple of centuries. Indeed, orthodontics in the United States and other developed nations is a booming business—more and more of us have crowded, poorly aligned teeth that need to be fixed.”

“Experimental research involving feeding soft- and hard-textured foods to laboratory animals indicates the tremendous importance of food texture and its influence on the masticatory complex. This research provides unequivocal evidence that habitual consumption of overly soft or otherwise highly processed foods promotes occlusal abnormalities—crooked teeth, misaligned jaws, and chewing problems. The bioarchaeology results are especially revealing—with few exceptions, when people shifted from eating hard-textured foods (mostly hunter-gatherers) to eating soft-textured foods (mostly agriculturalists), there was an increase in occlusal abnormalities. In more recent times, as our food has become increasingly processed, malocclusions have increased apace.” (pp. 113-114)