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Should You Be Eating Like A Caveman, Or Has Your Stomach Evolved?

A new book is targeting misconceptions about prehistoric humanity—including the idea that a diet without bread, dairy, or sweets is healthier for us.

Should You Be Eating Like A Caveman, Or Has Your Stomach Evolved?

When evolutionary biologist Marlene Zuk set out to write about rapid human evolution and misconceptions about humanity’s distant past, she wasn’t expecting to publish a takedown of the popular paleo diet. Paleo, or "caveman" eating, eschews processed foods, bread, dairy, and beans for a simpler diet of meat, fruits, and vegetables and is having a bit of a cultural moment right now. However, Zuk’s book Paleofantasy: What Evolution Really Tells Us About Sex, Diet, And How We Live is being interpreted by reviewers as exactly that. That’s no surprise—as the subtitle indicates, publisher W.W. Norton knows paleo sells.

"It’s a book about evolution, not a book about diet," Zuk told Co.Exist. "But there is a pervasive idea that humanity is mismatched to the modern environment. We’re not." In the book, Zuk notes that the popularity of the paleo diet, along with the closely intertwined CrossFit exercise program, rest on a set of misconceptions about paleolithic humanity. Rather than the masses dying at 45 from disease, prehistoric lifespan expectancy was skewed by massive infant mortality rates—there were senior citizens then, just as now. Paleolithic humanity didn’t have stable diets of meat, vegetables, and fruit; eating habits varied widely based on geographic locations. Instead of engaging in sharp sprints of hunting activity, ancient humanity appears to have embarked on marathon-style runs just as often—the better to literally exhaust animals to death with.

At the core of the paleo diet, which supports a massive cottage industry of books, cookbooks, blogs, and food suppliers, is the idea that the shift to agriculture was unhealthy for humanity. Bread, legumes, dairy products, rice, sweets, and other staples of our historical diet dating back to Sumeria, in the paleo mindset, aren’t what the human body is designed for. Proponents such as Loren Cordain emphasize that humanity, for the bulk of its history, survived on meat, berries, and vegetables, and did just fine.

To that, Zuk’s main rejoinder is that humanity has undergone rapid biological evolution. Over a phone conversation, she emphasized that milk drinking among adults was an example of extremely rapid biological evolution—in a biological blink of an eye, mutations that allowed adults to process the chemicals in milk spread over wide swaths of the globe. Although only 35% of humanity can successfully process milk, they are of disproportionate Northern European, Middle Eastern, and African origins.

In one of the book’s most entertaining passages, Zuk talked about attending a conference where Cordain spoke about leaky gut syndrome, a sort of autoimmune condition possibly caused by certain foods which is exactly as unpleasant as it sounds. Cordain, when prompted by Zuk, said 10,000 years was not long enough for humanity to eat certain foods such as root beer and potatoes. Zuk, however, argues rapid evolution has made it possible for humanity to eat certain foods— everything from bacon to the molecular gastronomy delights of Alinea—that our cave-dwelling ancestors never could have imagined.

One of the most salient points the book brings up is that the introduction of agriculture, in the long run, benefited humanity. While paleo diet proponents are indeed correct that the archaeological record shows increased illness rates and malnutrition in the centuries following the adoption of agriculture, the human race rebounded in the long run.

"Initially, agriculture seems to have been associated with a high rate of noninfectious diseases like pellagra (a chronic lack of niacin), because early agriculturalists ate a smaller variety of foods. But then at least one study shows that by about 4,000 years ago, Egyptian skeletons were back to preagricultural size, and only 20% showed signs of poor nutrition," Zuk says.

Then there is the fact that the word "agriculture" itself covers a massive range of food cultivation methods—everything from ancient grain-grinding in the Middle East to the gigantic industrial beef processing facilities of today. As Zuk puts it in the book, these distinctions matter because "it is easier to accuse Monsanto-like agribusiness of causing widespread obesity and hypertension than it is to do the same thing to a few dozen people scrabbling in the ground for tubers using pointed sticks."