The Paleo diet is simple: Beyond processed junk foods, it also prohibits dairy, grains, peanuts, lentils, beans, peas and other legumes. You need to skip the salt shaker and drink only water, coconut water, or green teen (but just the organic kind). If you need something sweet, raw honey and coconut palm sugar are your options—but only in limited amounts. What can you eat when you’re eating like a caveman? You have your choice of lean meats, fish and shellfish, fruits and vegetables, and nuts and seeds. 

 

As the claim goes, the human body evolved to thrive in the Stone Age, and our genetic makeup has changed little since then. It was the invention of agriculture and the rapid rise of the food industry that brought us the joys of processed and packaged foods, corn syrup, and artificial sweeteners—the things that are damaging our health, bumping up dramatically the number of diseases we wrestle with and killing us slowly.

 

But the central principles behind the diet are fatally flawed.

 

While understanding how we evolved could, in theory, help us make the healthiest dietary decisions, and we have in fact carried forward a number of physical traits of our caveman ancestors, the logic falls down when you try to go any further than that, from the arbitrary choice of this very specific band of years to the mistaken claim that we are biologically the same still, 250,000 years later, to ignoring or rejecting the real, documented health benefits of modern foods.

 

Paleolithic Fantasies

 

In her book Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live, evolutionary biologist Marlene Zuk calls the basic tenets of the Paleo diet exactly that: Paleofantasies. Proponents of the diet and lifestyle are working from the daydream that once upon a time, our ancestors were perfectly in sync with the world they lived in, perfectly fit and perfectly healthy. But, Zuk says, “No such time existed.” The selection of that narrow band of human history to the exclusion of other periods of human evolution, in fact, has no real logic behind it—and scientists say a specific period of time in which all these foods were consumed probably does not actually exist.

 

Evolutionary Dead Ends

The Paleo diet insists that we are biologically identical to stone-age humans—ignoring the fact that the human genome has changed significantly in the past 10,000 years. Humans have actually evolved to not just tolerate dairy but to use it efficiently as a good source of calcium and vitamins. Lactose tolerance is actually a mutation that keeps the lactase enzyme active even after infancy. Plus, the bacteria in our intestines have evolved to help us break down the fibers of cultivated plants as agriculture was developed.

 

The Evolution of Food

 

The cavemen didn’t have access to cows or fields of wheat, and therefore milk and grains are unhealthy. But that’s dismissing an entire body of research that shows modern foods are tremendously beneficial for us.

 

A study showed that adults who consume low-fat dairy are 54% less likely to develop high blood pressure. Fiber from whole grains is known to reduce blood cholesterol levels and lower risk of heart disease, obesity, and type 2 diabetes. Beans are high in antioxidants, fiber, protein, B vitamins, iron, magnesium, potassium, copper and zinc, and decrease the risk of diabetes, heart disease, and colorectal cancer. In fact, the American Dietetic Association notes that Paleo diet restrictions and limitations make it unsustainable because of that lack of variety and potential nutrient inadequacies, when entire food groups are eliminated.

 

What Were They Really Eating?

 

Some Paleo dieters argue that following the Paleo diet is just using our ancestors as an example—but as it turns out, eating like a caveman is impossible because we don’t actually have enough scientific evidence to really know how cavemen were eating.

 

Even were we to pretend we knew exactly what they were eating and how, we still couldn’t even actually truly mimic the diet: wild game is not readily available and most modern plant food is cultivated. More importantly, every species of both animal and plant that we eat today is completely different from its Paleolithic predecessor via artificial selection at the hands of humans. At best, you can eat a modified version of the original diet that's completely organic, free-range and gluten-free—and that’s where the costs start to add up.

 

The Bottom Line

 

In the end, possibly the most important thing to note is that the human genome has changed significantly in the past 10,000 years as our diet has evolved. And if humans could only thrive in their ancestor’s exact circumstances the human species would not have lasted 250,000 years.

One thing the Paleo diet does get right, and something we already know: cutting out processed foods including white bread and refined sugars, packaged meats full of nitrates and junk food reduces the risk of heart disease and certain cancers, help control blood sugar, and prevent weight gain and type 2 diabetes. Eating right doesn’t have to be primitive.

 

Hungry for more? See our latest infographic on “Debunking the Paleo Diet.”