The evolution of diet and how humans evolved to be who we are today is crucial in understanding how we should and shouldn’t eat and live. It reinforces how living and raising our future generations (our precious babies) in a Paleo way is the best and most natural way forward. If we have any hope to reduce the increasing numbers of Type 2 Diabetes, Autism, Developmental delays, Obesity, Heart disease autoimmune diseases and Cancer, it’s understanding what our bodies and brains thrive on and what our bodies and brains fail on.
Eating meat is thought by some scientists to have been crucial to the evolution of our ancestors’ larger brains about two million years ago. By starting to eat calorie-dense meat and marrow instead of the low-quality plant diet of apes, our direct ancestor, Homo erectus, took in enough extra energy at each meal to help fuel a bigger brain. Digesting a higher quality diet and less bulky plant fiber would have allowed these humans to have much smaller guts. The energy freed up as a result of smaller guts could be used by the greedy brain, according to Leslie Aiello, who first proposed the idea with paleoanthropologist Peter Wheeler. The brain requires 20 percent of a human’s energy when resting; by comparison, an ape’s brain requires only 8 percent. This means that from the time of H. erectus, the human body has depended on a diet of energy-dense food—especially meat.
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.
Fast-forward a couple of million years to when the human diet took another major turn with the invention of agriculture. The domestication of grains such as sorghum, barley, wheat, corn, and rice created a plentiful and predictable food supply, allowing farmers’ wives to bear babies in rapid succession—one every 2.5 years instead of one every 3.5 years for hunter-gatherers. A population explosion followed; before long, farmers outnumbered foragers.
Over the past decade anthropologists have struggled to answer key questions about this transition. Was agriculture a clear step forward for human health? Or in leaving behind our hunter-gatherer ways to grow crops and raise livestock, did we give up a healthier diet and stronger bodies in exchange for food security?
When biological anthropologist Clark Spencer Larsen of Ohio State University describes the dawn of agriculture, it’s a grim picture. As the earliest farmers became dependent on crops, their diets became far less nutritionally diverse than hunter-gatherers’ diets. Eating the same domesticated grain every day gave early farmers cavities and periodontal disease rarely found in hunter-gatherers, says Larsen. When farmers began domesticating animals, those cattle, sheep, and goats became sources of milk and meat but also of parasites and new infectious diseases. Farmers suffered from iron deficiency and developmental delays, and they shrank in stature.
Studies suggest that indigenous groups get into trouble when they abandon their traditional diets and active lifestyles for Western living. Diabetes was virtually unknown, for instance, among the Maya of Central America until the 1950s. As they’ve switched to a Western diet high in sugars, the rate of diabetes has skyrocketed. Siberian nomads such as the Evenk reindeer herders and the Yakut ate diets heavy in meat, yet they had almost no heart disease until after the fall of the Soviet Union, when many settled in towns and began eating market foods. Today about half the Yakut living in villages are overweight, and almost a third have hypertension, says Leonard. And Tsimane people who eat market foods are more prone to diabetes than those who still rely on hunting and gathering.
(Excerpts from The Evolution of Diet, BY ANN GIBBONS)