Gibbons' "The Evolution Of Diet"

National Geographic

Some experts say modern humans should eat from a Stone Age menu. What's on it may surprise you.

It’s suppertime in the Amazon of lowland Bolivia, and Ana Cuata Maito is stirring a porridge of plantains and sweet manioc over a fire smoldering on the dirt floor of her thatched hut, listening for the voice of her husband as he returns from the forest with his scrawny hunting dog.

With an infant girl nursing at her breast and a seven-year-old boy tugging at her sleeve, she looks spent when she tells me that she hopes her husband, Deonicio Nate, will bring home meat tonight. “The children are sad when there is no meat,” Maito says through an interpreter, as she swats away mosquitoes.

Nate left before dawn on this day in January with his rifle and machete to get an early start on the two-hour trek to the old-growth forest. There he silently scanned the canopy for brown capuchin monkeys and raccoonlike coatis, while his dog sniffed the ground for the scent of piglike peccaries or reddish brown capybaras. If he was lucky, Nate would spot one of the biggest packets of meat in the forest—tapirs, with long, prehensile snouts that rummage for buds and shoots among the damp ferns.

This evening, however, Nate emerges from the forest with no meat. At 39, he’s an energetic guy who doesn’t seem easily defeated—when he isn’t hunting or fishing or weaving palm fronds into roof panels, he’s in the woods carving a new canoe from a log. But when he finally sits down to eat his porridge from a metal bowl, he complains that it’s hard to get enough meat for his family: two wives (not uncommon in the tribe) and 12 children. Loggers are scaring away the animals. He can’t fish on the river because a storm washed away his canoe.

The story is similar for each of the families I visit in Anachere, a community of about 90 members of the ancient Tsimane Indian tribe. It’s the rainy season, when it’s hardest to hunt or fish. More than 15,000 Tsimane live in about a hundred villages along two rivers in the Amazon Basin near the main market town of San Borja, 225 miles from La Paz. But Anachere is a two-day trip from San Borja by motorized dugout canoe, so the Tsimane living there still get most of their food from the forest, the river, or their gardens.  I’m traveling with Asher Rosinger, a doctoral candidate who’s part of a team, co-led by biological anthropologist William Leonard of Northwestern University, studying the Tsimane to document what a rain forest diet looks like.

They’re particularly interested in how the Indians’ health changes as they move away from their traditional diet and active lifestyle and begin trading forest goods for sugar, salt, rice, oil, and increasingly, dried meat and canned sardines. This is not a purely academic inquiry. What anthropologists are learning about the diets of indigenous peoples like the Tsimane could inform what the rest of us should eat.

Rosinger introduces me to a villager named José Mayer Cunay, 78, who, with his son Felipe Mayer Lero, 39, has planted a lush garden by the river over the past 30 years. José leads us down a trail past trees laden with golden papayas and mangoes, clusters of green plantains, and orbs of grapefruit that dangle from branches like earrings. Vibrant red “lobster claw” heliconia flowers and wild ginger grow like weeds among stalks of corn and sugarcane. “José’s family has more fruit than anyone,” says Rosinger.

Yet in the family’s open-air shelter Felipe’s wife, Catalina, is preparing the same bland porridge as other households. When I ask if the food in the garden can tide them over when there’s little meat, Felipe shakes his head. “It’s not enough to live on,” he says. “I need to hunt and fish. My body doesn’t want to eat just these plants.”

As we look to 2050, when we’ll need to feed two billion more people, the question of which diet is best has taken on new urgency. The foods we choose to eat in the coming decades will have dramatic ramifications for the planet. Simply put, a diet that revolves around meat and dairy, a way of eating that’s on the rise throughout the developing world, will take a greater toll on the world’s resources than one that revolves around unrefined grains, nuts, fruits, and vegetables.

Until agriculture was developed around 10,000 years ago, all humans got their food by hunting, gathering, and fishing. As farming emerged, nomadic hunter-gatherers gradually were pushed off prime farmland, and eventually they became limited to the forests of the Amazon, the arid grasslands of Africa, the remote islands of Southeast Asia, and the tundra of the Arctic. Today only a few scattered tribes of hunter-gatherers remain on the planet.

That’s why scientists are intensifying efforts to learn what they can about an ancient diet and way of life before they disappear. “Hunter-gatherers are not living fossils,” says Alyssa Crittenden, a nutritional anthropologist at the University of Nevada, Las Vegas, who studies the diet of Tanzania’s Hadza people, some of the last true hunter-gatherers. “That being said, we have a small handful of foraging populations that remain on the planet. We are running out of time. If we want to glean any information on what a nomadic, foraging lifestyle looks like, we need to capture their diet now.”

So far studies of foragers like the Tsimane, Arctic Inuit, and Hadza have found that these peoples traditionally didn’t develop high blood pressure, atherosclerosis, or cardiovascular disease. “A lot of people believe there is a discordance between what we eat today and what our ancestors evolved to eat,” says paleoanthropologist Peter Ungar of the University of Arkansas. The notion that we’re trapped in Stone Age bodies in a fast-food world is driving the current craze for Paleolithic diets. The popularity of these so-called caveman or Stone Age diets is based on the idea that modern humans evolved to eat the way hunter-gatherers did during the Paleolithic—the period from about 2.6 million years ago to the start of the agricultural revolution—and that our genes haven’t had enough time to adapt to farmed foods.

A Stone Age diet “is the one and only diet that ideally fits our genetic makeup,” writes Loren Cordain, an evolutionary nutritionist at Colorado State University, in his book The Paleo Diet: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat. After studying the diets of living hunter-gatherers and concluding that 73 percent of these societies derived more than half their calories from meat, Cordain came up with his own Paleo prescription: Eat plenty of lean meat and fish but not dairy products, beans, or cereal grains—foods introduced into our diet after the invention of cooking and agriculture. Paleo-diet advocates like Cordain say that if we stick to the foods our hunter-gatherer ancestors once ate, we can avoid the diseases of civilization, such as heart disease, high blood pressure, diabetes, cancer, even acne.

That sounds appealing. But is it true that we all evolved to eat a meat-centric diet? Both paleontologists studying the fossils of our ancestors and anthropologists documenting the diets of indigenous people today say the picture is a bit more complicated. The popular embrace of a Paleo diet, Ungar and others point out, is based on a stew of misconceptions.