GOOD Asks the Experts: Is The "Paleolithic Diet" Really Better?

Since the beginning of civilization, humans have longed to return to a more primitive, simpler way of life. As soon as we had cities, we told stories about escaping them. The concept of the Appalachian Trail, organic agriculture, and Slow Food all arose from a dissatisfaction with technological advances. Now, as it becomes clearer and clearer that the "diseases of affluence"—obesity, diabetes, heart disease—are intrinsically linked to a modern diet and a sedentary way of life, it's time to consider a radical future for food.

What if that future involves going back in time—before the discovery of petroleum, before processed foods, and even before we cultivated starchy carbohydrates in what we now call agriculture? In the decades that followed S. Boyd Eaton's publication of "Paleolithic Nutrition" in the New England Journal of Medicine in 1985, the "paleo diet" has been touted as a solution to our modern ills.

Before we turn back the clock, let’s take a look at what it meant to eat like an early hominin. In the two and half million years since the dawn of the Paleolithic period, our ancestors evolved bigger brains, which required dietary changes and probably required cooking, as Richard Wrangham persuasively argues in his book Catching Fire: How Cooking Made Us Human. Evolution shaped our digestive system: We have a voluminous small intestine and a short lower gut adapted to make better use of meats and cooked or processed grains. Mutations allow us to produce lactase so we can drink mammary fluids (and eat cheeses) beyond infancy. We're more resistant to certain damaging compounds created when food is heated and poorly equipped to resist toxins found in raw meats.

Still, questions remain: Was eating during the Paleolithic period really healthier than the modern human diet? Or is the problem with highly processed, energy-dense, nutrient-poor foods? In other words, is the “paleo diet” especially healthy, or is our current diet just especially bad? To find out, I spoke with four experts for a scholarly, historical taste test of the Paleolithic diet.

Bill Leonard is an anthropologist at Northwestern University who studies physiology and nutrition in ancient humans and traditional cultures alive today. His latest paper looks at evolutionary patterns in diet and activity to understand modern health problems.

Peter Ungar is an evolutionary biologist and paleoanthropoligist at the University of Arkansas who reconstructs ancestral diets using dental morphology and microwear. His latest book is called Mammal Teeth.

Amanda Henry is a paleobiologist studying the evolution of the human diet at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Her latest research examined plant microfossils in Neanderthal teeth for evidence of cooking.

Katharine Milton is a physical anthropologist who studies the dietary ecology of primates at the University of California at Berkeley. She has published numerous papers on modern and ancient human diets.

GOOD: What do you think our ancestors were eating during the Paleolithic period?

Bill Leonard: When you’re talking about any evolutionary-designed human diet, it depends where you look. If you set our ancestral diet as the period of the last common ancestors of humans with apes, you’re going to get a very different perspective than if you set it at the origins of the genus Homo at 1.5 to 2 million years ago.

Peter Ungar: In general, over a long period of time, our ancestors developed an ability to take a broader and broader range of things into the diet. Tools, including fire, gave them access to an unprecedented variety of foods, which meant they could live in more places and find something everywhere they went. That is not true of chimpanzees, our nearest relatives.

Amanda Henry: Although there tends to be this lingering image of Neanderthals as living in the Ice Age, where it was cold and there were no plants, more recent research paints a more complex picture and even suggests that our ancestors predominantly ate plant foods.

Katharine Milton: Do you really think ancestral humans went out and said, “We’re going out to get some French fries today”? No, they said, “With any luck, praying to the sun God, or whomever we revere, we’re hoping to get something to eat.” They don’t care what it is—a lizard, an elephant, a bunch of fruit, roots, a bunch of grubs. The human diet has always been whatever you can get your mitts on that won’t kill you and you can digest. That’s it. Simple as pie.

GOOD: When you look at popular representations of early humans—in the American Museum of Natural History’s diorama of Neanderthals, in Gary Larson’s "The Far Side," or in books advocating a paleo diet—meat often appears central to the diet. How important is meat?

Leonard: Although there’s an extraordinary range of variation, based on the climate and the environment, hunter-gatherers get a fair amount of meat in their diet. We require a diet that is more energy-dense than other primates and historically, we may have reached that point by incorporating more meat. It’s reflected in evolutionary changes in our face, our teeth, and in our gastrointestinal tract. Indeed, the GI tract of modern humans looks more like a carnivore's than a large primate's. Because early humans increasingly used tools to hunt, we don't show the same kinds of dental adaptations as modern carnivores.

Ungar: Two and half million years ago, we see enamel on the teeth of our ancestors get thinner; the teeth become smaller and more crested. The teeth can wear down and you get sharp edges that you didn’t have before. So we start to see ability to shear and slice with early Homo, which could indicate the consumption of some tougher foods such as meat.

Henry: Looking at plant micro-remains—tiny residue of plants—on the mineralized plaque of Neanderthal remains, it appears they were eating date fruits, starchy tubers, and wild relatives of barley. Not only were they eating them, they were cooking them too.

Milton: Humans evolved to eat a high-quality diet, but that doesn’t mean eating a lot of meat—especially today. Even the Eskimos and Inuits don’t eat a lot of meat. They eat marine mammal fat. No one eats a lot of meat. The only people who eat way too much meat are Americans, who are addicted to eating huge steaks, chops, and roasts.

GOOD: How much diversity was there in the diet and how much food processing was involved?

Leonard: There are lots of ways you can improve dietary quality—eating meat, cooking, or processing starchy carbohydrates. These are all human strategies for making food digestible and nutrients more bio-available. To argue that meats are the only strategy is as misguided as thinking that humans were evolved to be folivores, entirely vegetarian.

Ungar: While there’s increasing evidence of meat consumption from the first evidence of butchery 2.5 million years ago to around 1.8 million years ago, when we see sites with lot of bones, we still don’t know how that breaks down in terms of the ratio of meat to plant material. What we do know is that no single food provided a panacea.

Henry: In the early Upper Paleolithic periods, there’s evidence early humans were making flours and pastes. Even earlier, the Neanderthals in the Middle Paleolithic were cooking. That’s some of the oldest cooking—technically, heating in the presence of water—where they were taking a raw starch and turning it into something your body can process.

Milton: No matter where they evolved, our diet changed continuously, just like if you’re a primate living in the tropical forest. Every day a monkey in a tree does not eat the same thing; it may eat four or five kinds of leaves, one or two fruits, maybe some flowers. The next day, there’s 50 to 75 percent turnover in what that same monkey is eating and I assume that Paleolithic humans were the same way. Each day, they need to take in a sufficiency of good quality energetic substrate (sugars and starches) and enough protein—say 70 grams or so—to meet their daily requirements for amino acids.

GOOD: Judging by the proliferation of diet books, we’re really fascinated with the paleo diet. Some people swear by it and say it’s best to eat foods humans evolved to eat. Should I try it?

Leonard: In the modern, industrial world, we have become ever better at creating diets that are dense in calories and don’t require a lot of energy to procure them. No one recommendation is going to fit everybody, so the challenge is to find what works for you individually, and, at the same time, what fits the broad nutritional requirements of our species.

Ungar: There was no single Paleolithic diet. Still, I think these are valuable diets in that they remind us what we shouldn’t be eating. Our ancestors didn’t have the processed foods we have today. To say what we should be eating is more difficult, but I can tell you without a shadow of a doubt that australopiths did not eat corn dogs and drink milkshakes.

Henry: The diet may be perfectly good, but its theoretical underpinnings are wrong. The Paleolithic period is very long and very varied. Are you talking about the Middle Stone Age of Africa? Or the Upper Paleolithic of Europe. They were eating completely different things. We’re in a quest to understand that, but, to say, this is how you have to eat because this is how our ancestors ate is a fallacy.

Milton: While I don’t know what the paleo diet is, what I do know is that if you’re talking about trying to eat unprocessed foods, a high percentage of fruits and vegetables, and only as much animal source as you need to meet protein and essential amino acid requirements, then that’s a good diet, especially if you get up and around for an hour each day out in the fresh air.

Top illustration: Sara Saedi/GOOD; Second illustration via Harper's Magazine. Third chart showing monkey via Katharine Milton in Scientific American. 1993:269; Fourth photo of Neanderthal Diorama in the American Museum of Natural History, New York via American Anthropologist ©American Anthropological Association; Fifth illustration of grasses found cave paintings in Parpalió, Spain, Montgaudier, France, and Trilobite, France, via The Nature of Paleolithic Art. Bottom photo (cc) Flickr user Lord Jim.