Via NPR blogs, an article by a biological anthropologist concerned about the growing-in-popularity “paleo diet”. She makes some very sound points, some that I think are a bit misleading, and overall it provides a fantastic show-and-tell framework for a blog post.
In a few days, the world’s population will reach 7 billion. Only a tiny fraction of this number still makes a living by hunting and gathering, the way all our ancestors did before about 12,000 years ago.
True this. And it’s entirely possible that that ancestral population wasn’t all THAT much larger than the one that still makes its living hunting and gathering now; we came from a pretty small and spread-out initial population, when we appeared as a distinct species. There’s no question agriculture is what allowed us to number in the billions in the first place.
According to a set of claims relentlessly pushed in some books and blogs, as many modern humans as possible should adopt a hunter-gatherer diet. That is, we should eat lean meat and vegetables because our Paleolithic hunting-and-gathering ancestors did. At the same time, we should refuse dairy, grains and sugars because our hunting-and-gathering ancestors didn’t eat these items.
Well, to be fair it’s a bit more complicated than that- the exact claim is that as many modern humans that lead modern lifestyles should adopt such a diet if they wish to remain lean and metabolically healthy, because a high fraction of grains and sugars leads to an overdose of insulin and blood sugar, causing an array of metabolic ills. Ultimately, high fractions of grains and sugars are said to do so because they were much scarcer in the ancestral diet.
Granted, a depressing number of “paleo” adherents really do seem to think it’s possible to re-enact Paleolithic life in modern times and that we really should eat just the way our ancestors ate, so it’s still a fair ding.
You might think that, as an anthropologist, I’d greet this embrace of the human prehistoric past with unalloyed delight, especially in a country where a high percentage of our population is evolution-averse. Like most anthropologists, though, I don’t think there’s good science behind these claims…It’s best to clarify right off that leaders of the paleo-diet movement don’t think monolithically. Lean meat and veggies take center stage, but the emphasis may vary in details such as how much seafood to eat. A look at the current issue of Paleo — a magazine devoted to “modern primal living” — indicates that, in addition to food, paleo-faddists think hard about exercise and lifestyle choices.
“Faddist” dismissal or no, this is fair. “Don’t think monolithically” is if anything an understatement- there’s a huge amount of variation in what people think is “paleo-acceptable” (dairy deserving its very own Thunderdome as a subject), and even faddist isn’t an entirely inaccurate claim. But there’s also a pretty strong backbone of people who start from biochemistry and then go to what imagined cavemen’s dietary patterns must have been like.
Some of them, in fact, take a paleo-lifestyle to startling lengths. In profiling this “modern-day Stone Age subculture” and its leaders, Arthur de Vany and Loren Cordain, the German magazine Der Spiegel interviews disciples who run through the undergrowth and eat wild boar in explicit emulation of their Paleolithic forebears.
Wild boar is delicious and sprinting down game is about as rigorous an exercise program as you can find, should you be able to hack it. Tongue out of cheek, I agree this is a bit extreme but given hobbies like base-jumping don’t exactly see why it’s all that hair-raising. Humans do far stranger things, up to and including in the game of healthfulness.
When I’ve interacted online with paleo-diet fans, though, I’ve found the great majority to be measured and thoughtful. With them, I worried aloud about the consequences of urging even more carnivory than we’ve already got. Largely, but not 100 percent, a vegetarian, I don’t tell others what to eat. But the paleo-movement seems to doom (even if unintentionally) more animals to life and death in factory farms. A greater percentage of grain crops would also be diverted to rich countries’ animals and away from poor countries’ people.
This is both fair, and not. She goes on to clarify a bit…
What I learned is that some paleo-dieters reject the eating of animals from factory farms. Some don’t eat much meat at all, focusing instead on avoiding grains and sugary foods.
“Some” makes it sound like a minority, but just about every source I’ve ever read is pretty firm on the point that factory-farmed meat is not just ethically questionable, but actively nutritionally worse than pastured, humanely raised meat. You are what you eat, and grain-fed and factory-farmed meats tend to have a much lower proportion of omega-3 fatty acids than their freer and happier cousins, with game meats being even better.
Caveats aside though, she has a valid point. There really isn’t enough meat to go around to feed everyone on the planet a meat-rich diet, not farmed meat and most certainly not wild meat. Our ancestors lived at far lower population densities than we do. There’s more than a little privilege inherent in being capable of entertaining living mostly off fresh meat and vegetables at all, especially the more expensive (because it is less efficient to raise) organic, grass-fed, free-range, hormone and pesticide free kinds.
There’s also more than a little privilege in presuming to decide what kind of diet people should eat based on the global population. One reason poorer areas of the world do well on a primarily farmed, primarily grain-based diet, at least in terms of measures like obesity and diabetes, is that they can’t afford to eat as much as they may want, and besides that they spend huge portions of their day on hard manual labor; it isn’t a paleolithic pattern, but it is a pattern that demands massive amounts of glycogen to sustain the activity level. They need dense carbohydrates to get through life. Data entry technicians do not, and they can afford all the food that is satiating and extra treats besides.
Many nutrition scientists give the paleo-diet a thumbs-down. They worry about its dearth of carbohydrates, its cost, its impracticality, and the fact that its boasts for good health are medically unproven.
It’s worth actually reading the article she linked to support her “thumbs-down” claim. It’s actually pretty inconclusive- it notes that there’s very little robust, long-term research on this eating pattern (perfectly true), acknowledges that it’s actually quite good for getting as much or more of your recommended dose of many nutrients as you need, and identifies as its primary concern the amount of fat you’re likely to take in. Which, a valid criticism of our current understanding of the role of fat in various negative health outcomes is that nutrition studies have traditionally been extremely poor at controlling for other variables- a study of “people who eat a lot of fat” versus “vegetarians”, for example, is highly likely to include a lot of people who eat a lot of junk food versus a lot of people who are very conscious of their health. A number of studies that have attempted tighter controls have found a far less tight link between fat intake and negative health outcomes- but again, this is a big area of just not enough research. We don’t really know.
For my part, I’ll focus on the paleo-anthropology.
Our ancestors began to eat meat in large quantities around 2 million years ago, when the first Homo forms began regular use of stone tool technology. Before that, the diet of australopithecines and their relatives was overwhelmingly plant-based, judging from clues in teeth and bones. I could argue that the more genuine “paleo” diet was vegetarian.
She could, but it would be disingenuous. Australopithecines were not modern humans, and there is plenty of evidence that their diet was radically different from ours. Two million years is a lot of time, and our jaw and tooth morphology especially changed dramatically from that of the australopithecines- away from that suited for tons of fibrous plant foods.
More worrisome are persistent attempts to match a modern diet to an “average” Paleolithic one, or Loren Cordain’s insistence that “we were genetically designed to eat lean meat and fish and other foods that made up the diet of our Paleolithic ancestors.”
Here’s where science most forcefully speaks back.
She’s right. There is no single ancestral human diet. We specialized in adaptability, and the available anthropological evidence is all over the map regarding what we ate. This is by far my biggest problem with the paleo movement as a whole. See John Hawks’s archive of posts on the diets of ancient humans and hominids for a picture of just how varied that could be.
First, ancient hunter-gatherer groups adapted to local environments that were regionally and seasonally variable — for instance, coastal or inland, game-saturated or grain-abundant (eating grains was not necessarily incompatible with hunter-gatherer living).
This is, again, a bit disingenuous. Grains period may not have been outside the paleolithic experience, but there’s little question they had absolutely nothing like our domesticated, starch-stuffed cereal crops. Paleo people who act as though any grain seed will kill them are silly, but an ancient hunter-gatherer’s seeds weren’t pretty much just like a plate of pasta, either.
Second, genes were not in control. People learned what worked in local context for survival and reproduction, and surely, just as in other primates, cultural traditions began to play a role in who ate what
Still a few degrees off what I’d consider straightforward truth. Genes don’t control us, especially in cultural foodways, but they sure as hell influence us- the most dramatic example is the persistence of lactase into adulthood that is widespread in some cultural groups but absent in others, and apparently new but rapidly on the rise in still others. Less dramatic but still most definitely there are differences in how well and efficiently we produce amylase, an enzyme that handles the starches found in grains, as well as genetic differences in insulin sensitivity.
Humans vary biochemically as much as they do physically, and some of it absolutely has to do with evolved adaptations to different dietary strategies.
I’m left wondering what’s the payoff to be had for pushing a popular diet as rooted in a mythically homogeneous, predictable human past. The lure of a good story may play a role. It’s a mighty powerful image: our ancestors roaming over the landscape, perfectly in tune with their bodies and the environment. Some of my anthropologist colleagues refer to this pining for a pristine past as a paleo-fantasy.
On this point I’m in absolute agreement with her. I’ve seen some damn bizarre ideas put forth as what our pure and natural ancestral state was- most especially the idea that that was ever a single state to begin with- and I find equally amazing the idea that “cavemen” were all fantastically healthy and athletic. Modern hunter-gatherers aren’t- it’s a very hard lifestyle, and it will wear your body out even if heart disease and diabetes aren’t among your problems.
It’s not paleo-fantasy that’s going to help us negotiate a healthy future, the 7 billion of us together, on this environmentally-endangered planet.
No, but all 7 billion of us don’t and won’t live in a unitary culture, lifestyle, or diet any more now than we did 50,000 years ago, and it’s pretty high-handed to tell a wealthy first-worlder in a northern climate with a sedentary job that he should eat like a third-world subsistence farmer- or, for that matter, to tell the farmer that he should stick with that lifestyle because it’s better for his health and cheaper to sustain. I don’t think there’s any particular danger that the whole world is going to start eating “paleo” and endanger the environment any more than I think there’s a particular danger that spinning classes are going to take the planet by storm.
I seem to have spent more time agreeing with her than not, but the areas of not are still pretty nontrivial. Paleolithic peoples’ diets may have been much more varied than Loren Cordain thinks, varying by season and locale, but that still doesn’t mean that because some populations ate a lot more tubers and wild seeds than others, that’s pretty much just like a diet based on bread, pasta, and potatoes is good for any modern human that doesn’t burn off all the extra glucose going through hours and hours of strenuous daily activity. Because australopithecines were primarily vegetarian, doesn’t mean the hominids that we became didn’t become much more dependent on animal flesh, whether on land or sea, and that those changes aren’t reflected in our morphology and our biochemistry.
Genes may not determine our destiny, but that likewise doesn’t mean that someone whose ancestors had been eating cereal grains for nine thousand years and has three times the amylase production of someone whose ancestors had been hunting, fishing, and dairying somewhere frozen for the same length of time will have exactly the same metabolic experience eating a bowl full of rice- or for that matter a glass of milk and a bear steak.
We can’t sustain the entire planet on wild boar and fiddlehead ferns, but that doesn’t mean that an individual person whose primary concerns are his serum triglycerides, waistline, and blood sugar numbers should consider himself identical to someone whose primary concerns are the monsoon season, his subsistence income, and the early arthritis in his elbows and knees when it comes to deciding what he should eat or how he should move.