The following is an excerpt from “The Evolution of Diet,” National Geographic Magazine, September 2014


Credit: National Geographic

Credit: National Geographic

“The real Paleolithic diet, though, wasn’t all meat and marrow. It’s true that hunter-gatherers around the world crave meat more than any other food and usually get around 30 percent of their annual calories from animals. But most also endure lean times when they eat less than a handful of meat each week. New studies suggest that more than a reliance on meat in ancient human diets fueled the brain’s expansion.

Year-round observations confirm that hunter-gatherers often have dismal success as hunters. The Hadza and Kung bushmen of Africa, for example, fail to get meat more than half the time when they venture forth with bows and arrows. This suggests it was even harder for our ancestors who didn’t have these weapons. “Everybody thinks you wander out into the savanna and there are antelopes everywhere, just waiting for you to bonk them on the head,” says paleoanthropologist Alison Brooks of George Washington University, an expert on the Dobe Kung of Botswana. No one eats meat all that often, except in the Arctic, where Inuit and other groups traditionally got as much as 99 percent of their calories from seals, narwhals, and fish.

So how do hunter-gatherers get energy when there’s no meat? It turns out that “man the hunter” is backed up by “woman the forager,” who, with some help from children, provides more calories during difficult times. When meat, fruit, or honey is scarce, foragers depend on “fallback foods,” says Brooks. The Hadza get almost 70 percent of their calories from plants. The Kung traditionally rely on tubers and mongongo nuts, the Aka and Baka Pygmies of the Congo River Basin on yams, the Tsimane and Yanomami Indians of the Amazon on plantains and manioc, the Australian Aboriginals on nut grass and water chestnuts.”


“Can you hear me okay?” Ann said, her voice barely audible over the blaring intercom announcements and indiscriminate roar of an airport terminal. “It’s a little loud in here!”

I turned up the volume on my iPhone as high as I could and yelled back, “We’re good! Let’s do this!”

I was speaking with award-winning science writer Ann Gibbons about “The Evolution of Diet,” a piece she authored for the September 2014 issue of National Geographic. Ann has been a correspondent for Science magazine for over 20 years, covering the subject of human evolution for nearly as long, but when National Geographic approached her about tackling the evolution of the human diet, she quickly agreed. “I’ve always been drawn to these subjects,” she said. “How modern humans came out of Africa, how they’ve changed due to disease, habitat and diet—I thought it would be interesting to study the diets of hunter-gatherers.”

Africa, the ancestral homeland of all humans and realm of the Hadza, the last of the true hunter-gatherers, was an obvious detour on Ann’s global tour, but she didn’t want to stop there. “I wanted to look at people who were living nomadic lifestyles,” she said. “I wanted to find people who are still living off of land and water, and to observe the health changes that happen when they transition into Western diets.” With this broad lens, she took in a diversity of survival strategies, ecologies and food traditions, from the high mountains of Afghanistan to the banks of the Amazon River and everything in between.

© Matthieu Paley/National Geographic Young Hadza hunters survey the Yaeda Valley. (Tanzania)

© Matthieu Paley/National Geographic
Young Hadza hunters survey the Yaeda Valley. (Tanzania)

While much of the research for “The Evolution of Diet” was conducted online or through conversations with subject-matter experts like Harvard primatologist Richard Wrangham, Ann also made a point to experience the world of hunter-gatherers firsthand. “We went to Bolivia to visit the Tsimane,” she said. “To get there, I spent two days in a dugout canoe traveling through the Amazon rainforest.” Ann told me how the Tsimane were originally hunter-gatherers, but when Catholic missionaries arrived they were taught to grow crops like cassava and bananas in small gardens.

This survival strategy—a combination of hunting, gathering and cultivated gardens—is known as “forager horticulturalism,” and it allows the Tsimane to make it through the rainy season, when hunting is more difficult. Even during the best of times, however, Ann discovered that meat was difficult to come by for the Tsimane. “Even though the men hunt every day and with modern weapons like rifles, most days they still come home empty-handed,” she said. “They crave meat, but they rarely get it, so there is a large dependence on ‘woman the gatherer.’”

Most days, the Tsimane women prepare a bland porridge of cassava and plantain, but despite this starch-heavy regimen, the Tsimane are still remarkably healthy. In a study of over 2,000 Tsimane adults across 82 villages, it was found that only 3 percent of the population was hypertensive (defined as having blood pressure in excess of 139 systolic and 89 diastolic) and that in Tsimane men, diastolic blood pressure actually tends to go down with age. When comparing this number to the 33 percent of American adults who are hypertensive, the study author, UCSB anthropology professor Michael Gurven, noted that “

[o]ur classic risk factors for heart attack and stroke, such as high blood pressure, are not universal,” and suggested that a variety of factors including “greater exposure to pathogens, active lifestyle, high fertility, and traditional diet” might be the reason for the Tsimane’s relative freedom from chronic Western diseases.

When our conversation drifted to the subject of Western diseases, Ann mentioned that even in Western countries, diabetes, heart disease and obesity are relatively new phenomena. “Until recently, getting enough calories was the problem,” she said. “If you look at turn-of-the-century grave sites in London, you won’t find any obese people.” While I intellectually understand this, it’s hard for me to imagine a world in which the terms “fast food,” “fast casual,” “fine dining” and “buffet” don’t exist. Our problem isn’t finding food—it’s avoiding it. We have to actively limit our caloric intake, and even then we still have to go to the gym to burn off the excess. Ann’s travels have shown her a very different world, however, one in which food actively avoids or even attacks you. “They work so hard getting their food,” she said. “They live very active lives, and when they stop being active and move into settlements, they begin to experience all sorts of metabolic disorders.”

© Matthieu Paley/National Geographic Wande and her husband, Mokoa, set out to find food. She uses a blade- tipped stick to dig tubers, a staple food especially in the rainy season. He brings an ax to extract honeycomb from tree trunks and a bow and arrows for hunting and defense. (Tanzania)

© Matthieu Paley/National Geographic
Wande and her husband, Mokoa, set out to find food. She uses a blade- tipped stick to dig tubers, a staple food especially in the rainy season. He brings an ax to extract honeycomb from tree trunks and a bow and arrows for hunting and defense. (Tanzania)

With globalization and the rapid expansion of the middle class in countries such as China and India, worldwide rates of Western diseases are set to explode, but it is also worth noting that there is a growing pushback, as well. In her article, Ann acknowledges the Paleo diet as one response to the perceived disconnect between our bodies and our environment. When we talked about Paleo, she applauded the focus on whole, unprocessed foods—but she also had reservations. “I think it’s fabulous that it’s encouraging people to eat fruits, vegetables and nuts,” she said. “But I’m concerned about the amount of meat.” She noted that her experiences visiting modern hunter-gatherers did not confirm the “50 percent of calories from meat” claim found in Loren Cordain’s “The Paleo Diet.” She was also skeptical of the demonization of grains, noting that there is archaeological evidence suggesting grains were a part of the human diet long before the advent of the Agricultural Revolution and the Neolithic age.

It is a common misconception that all practitioners of the Paleo diet are unrepentant carnivores, piling meat upon meat upon meat. The reality, however, is much more nuanced than that. I have heard the phrase “more vegetables than a vegetarian” used by many Paleo dieters to describe the fact that plants make up a far greater percentage of their daily food intake than animals. In fact, the “Paleo Pyramid” found on the Paleo Magazine website lists “vegetables” before “meat and fish” as the foundation of a good Paleo diet. Even some grain consumption, typically in the form of white rice (à la “The Perfect Health Diet”) or the occasional corn tortilla (Mark Sisson recently addressed this on his Mark’s Daily Apple blog) has become an accepted practice by many Paleos.

As Ann discovered, there is no “one true Paleo diet,” and it is precisely because of our ability to adapt, either through our genes, technology or microbiome, that we are able to eat so many different things and live in so many different places. “We are all looking for the best, most healthy diet in this world of processed food,” she said, and I agree.



Hunter-Gatherers, Forager-Horticulturalists Demonstrate Minimal Hypertension and Lower Risk of Heart Disease:

All images from the September issue of National Geographic magazine.

Additional Links:

CARTA Symposium on The Evolution of Human Nutrition:

Paleo Pyramid: