Well, John’s book is finally done – and trust me, it’s worth the wait. Just don’t expect any recipes or meal plans (he’s a crummy cook). John begins by going behind the scenes at one of the world’s top zoos to learn how they keep animals healthy in captivity – hint: mimic their natural habitat – which kicks off a series of adventures exploring everything from the Bible’s obsession with hygiene to the British reputation for lousy teeth. John distills the lessons from his adventures and applies them to modern life – food, fasting, movement, bipedalism (standing, walking running), thermoregulation, sun, sleep, ethics, and the environment – showing how to craft a holistic primal lifestyle in the modern world. Entertaining and beautifully-written, The Paleo Manifesto is an accessible and credible defense of primal living that even skeptics will enjoy.
In this excerpt, John receives a private tour of Harvard’s fossil archive, holds the 80,000 year-old skull of a Paleolithic hunter-gatherer, and unravels the mystery of his amazing grin.
Five years after graduating, I found myself back on the Harvard campus in a familiar situation: late to meet with a professor. My destination? Harvard’s Peabody Museum of Archaeology and Ethnology.
The Peabody boasts a collection of over six million ancient artifacts from around the world: a shark tooth spearhead from the South Pacific; Mayan hieroglyphics engraved on giant limestone slabs; a Native American whistle carved out of eagle bone collected by Lewis and Clark on their legendary transcontinental expedition.
The Peabody is also where Harvard stores its osteological collections: bones. Lots of bones. Neanderthals from Europe, mummified remains from South America, chimpanzees from Africa. The collections contain fossils famous for documenting the emergence of human beings, as well as skulls with uncommon deformities used to teach students about skeletal development. Delicate and rare, the bones in the collections are locked away in an archive, not on display to the public.
I was meeting with Dr. Daniel Lieberman, chair of the Department of Human Evolutionary Biology. Bearded and bespectacled, he looked just like a professor should; he was the ur-professor. Dr. Lieberman studies bones, both dead bones (paleoanthropology) and living bones (biomechanics). He earned tenure by studying the human head, but he earns mention in ESPN stories for his research on barefoot running.
My visit today was all about the human head – skulls, actually – and the impact of the Agricultural Revolution on human health. Our diverse, omnivorous diet as hunter-gatherers became heavily grain-based, contributing to an overall decline in health—and I was about to hold the evidence in my own hands.
“Okay, let’s go see some skulls,” said Dr. Lieberman, as he led me into the museum.
We walked up to an old wooden door. Probably part of the original construction in the late nineteenth century, it had been retrofitted with an electronic security system. Dr. Lieberman swiped a key fob past it, the lock clicked open, and we walked into a brightly lit room with laboratory equipment lining one wall. It felt like moving from historic to modern, but we were actually moving from historic to prehistoric.
The archive felt like a cross between a library and a morgue. It was lined with shelves, which were filled with boxes of bones. Handwritten words faced outward: “Natufian—El Wad”; “Chimpanzee—Liberia.” The labels served the dual role of title and tombstone.
Dr. Lieberman handed me a pair of latex gloves.
“Here, put these on.”
The gloves weren’t there simply to protect the ancient remains from me; they were also there to protect me from the ancient remains, since many had been preserved in nasty chemicals.
Dr. Lieberman pulled a box off the shelf, carried it over to a table, and took off the lid. He gently lifted up a skull.
“This is Skhul V. This guy is famous. He was a hunter-gatherer living more than 80,000 years ago in the Levant. That’s modern-day Israel. He’s one of the earliest anatomically modern Homo sapiens ever recovered. Here, you can hold his skull. There’s only one rule.”
Dr. Lieberman paused and looked directly at me.
“Use two hands.”
It was a command, not a suggestion. This is not something you want to drop.
With that he gingerly passed me Skhul V.
Looking at a human skull creates an optical illusion: it looks like the skull is smiling. The brain interprets the visible teeth and upswept jawbone as an upturned mouth. Not only did this phenomenon create the creepy effect that Skhul V was somehow alive, but he seemed downright cocky, brimming with a confidence that even the grave couldn’t shake.
And what a grin this guy had. What an amazing grin.
“Notice anything?” Dr. Lieberman asked. “Look at the teeth. They’re straight. And no cavities. His wisdom teeth came in just fine. Humans, like all animals, have evolved teeth that are well suited to their natural diet. An infected tooth can easily kill you, and there were no dentists in the Paleolithic.”
Nearly one hundred thousand years before dentists and orthodontists, this hunter-gatherer had a strong, straight set of chompers. Skhul V challenged much of what I’d been taught about the history of human health.
“Now, look,” Dr. Lieberman continued, “hunter-gatherers didn’t have perfect teeth. This guy has well-worn teeth, and he’s actually missing one due to an abscess. So don’t stop going to the dentist. But wait until I show you the skulls of early farmers—a lot of them would need to get fitted for dentures.”
“So what’s the secret? Eat less sugar?” I asked.
“Well, yes, but healthy teeth depend on a variety of factors,” Dr. Lieberman explained. “First, yes, it matters what you eat. Amylase in your saliva breaks down carbohydrate into sugar in your mouth. Bacteria feed on the sugar and produce acid that wears away the enamel on teeth, giving you cavities. We’ll see what happened to the early farmers who started eating a starchier diet.”
To figure out what humans used to eat, teeth are a good place to start. Not only do teeth fossilize well, but they’re the first point of contact between the food we eat and our body, the first part of our internal digestive tract. And if our teeth aren’t well adapted to a particular food, it’s unlikely the rest of our digestive tract is. But whatever Skhul V was eating, his teeth seemed to be up to the challenge.
“It also matters how tough your food is to chew,” Dr. Lieberman continued. “When you put force on bones, they grow bigger and stronger. People back then ate tougher foods, they put larger forces on their jaw, and thus they had jaws large enough to actually fit all of our teeth. And those bite forces may have helped our teeth come in straight.”
“And since we all eat such soft foods these days?” I asked.
It felt oddly insulting to hear him say that. In a sense he was pointing out that my growth had been stunted in childhood. I’m deformed. And not just me, but most modern people.
Dr. Lieberman took the skull and put it back in the box, then pulled out a femur and held it up.
“I don’t know if you’ve seen many femurs, but I have, and this is quite a femur. He almost certainly has much thicker bones than either of us. Bone cross-sectional thickness increases with use, particularly before the mid-twenties. It suggests significant musculature.”
“He was tall, too,” Dr. Lieberman said as he held the femur up to my thigh. I’m five foot ten, and the femur was longer than mine. (Dr. Lieberman later sent me a published estimate on Skhul V: five foot ten and 150 pounds. “Yeah, I don’t believe it,” he said. “I suspect they estimated them wrong.”) Even so, five foot ten would have been considered gigantic from the Agricultural Revolution until recently. Early farming populations lost as much as five inches of height compared with early foragers.
“So how long did this guy live?” I asked.
“Well, this guy probably fits the stereotype of dying young,” Dr. Lieberman said. “Maybe thirty to forty years old. But life was dangerous back then, and it looks like he was healthy right up to the end. Plenty of ancient hunter-gatherers lived a long time. Contemporary hunter-gatherers regularly live well into their sixties and seventies.”
The common misperception is that ancient people would blow out the candles at their thirty-fifth birthday party and then just drop dead. But even chimpanzees and gorillas can live that long in the wild, and there are good reasons to believe we are naturally longer lived than they are. Humans have fewer natural predators than do other primates, as well as a longer childhood before puberty. The age of the oldest documented human (122 years old) far exceeds the oldest documented chimpanzee (66 years old) and gorilla (56 years old), both of which lived in captivity with no risk of predation or starvation. The natural human life span appears to have lengthened in the late Paleolithic when humans were able to fend off external sources of mortality and bear (or support) offspring at older ages. In fact, it’s likely that life expectancy initially dropped after the Agricultural Revolution.
The Agricultural Revolution seems like a paradox of history: if human health got worse, then why did people become farmers?
The shift to an agricultural lifestyle wasn’t something that anyone consciously planned. Even so, the domestication of animals and plants appears to have taken place independently in multiple locations around the world (the Fertile Crescent, China, India, the Americas, and Africa) at about the same time, 15,000 b.c. to 5,000 b.c. It was a technology whose time had come.
In short, the Agricultural Revolution unlocked a path to more rapid growth—in population, culture, and technology—and the people who took that path left descendants as numerous as the stars in the sky. A fifty-person band of hunter-gatherers—even if they are relatively tall and healthy—will be displaced by a wealthy, technologically advanced city-state with a fast-breeding population, many of whom could be enlisted as soldiers, even if they are short and sickly.
“Shall we go look at some diseased farmers?” asked Dr. Lieberman, and he led me to another part of the archive. He pulled out a couple more boxes of bones and placed them on the counter. He lifted up another skull, holding it for me to have a look. “This is an early Neolithic farmer from Tangier, in modern-day Morocco.”
Dr. Lieberman turned it over to show the dental cavity.
“These are some shitty teeth. Once you get farming, you get a lot more cavities. It’s classic.”
The teeth were ground flat, filled with holes, and many were missing. It looked brutally painful.
“By the way, it’s not just starch that causes this. It’s also the little bits of stone that get mixed into food when grinding grains. That’s why the teeth are all ground flat. And see how shiny they are? They’ve been polished by the stone bits, like by sandpaper. A lot of starch, plus wear and tear, and a poor diet make for a lot of dental problems.”
Dr. Lieberman put the Moroccan farmer away and opened another box.
“We’ve got lots of diseased farmers. This guy is from the fifteenth century in modern-day Montenegro.”
He held up the skull. There were long gaps where teeth were missing. Based on the bones, he wasn’t much more than five feet tall.
“This is a squat little person who had a horrible, nasty life,” Dr. Lieberman observed. “I know you’re focused on diet, but probably the biggest negative impact on the overall health of early farmers came from infectious disease: a result of living in close proximity to other people and domesticated animals for the first time.”
What Dr. Lieberman said confirmed my basic take on the story of human health. It wasn’t one uninterrupted improvement. Things got worse before they got better. Teeth got worse, stature declined, infectious disease went through the roof, and life span declined for the average person.
“Just don’t forget that the Agricultural Revolution allowed more people to survive. All of us wouldn’t be here without it,” Dr. Lieberman said as he packed up the bones.
“Speaking of the Agricultural Revolution, who’s hungry for lunch?”