The Paleolithic period, the Stone Age, only goes back about two million years. Humans and other great apes have been evolving for the last 20 million years, starting back in the Miocene era. We hear a lot about the Paleolithic diet, but that just represents the last 10% of hominid evolution—what about the first 90%?

During the Miocene era, the diet is generally agreed to have been a high-fiber, plant-based diet. For the vast majority of our family’s evolution, we ate what the rest of our great ape cousins eat—leaves, stems, and shoots (in other words, vegetables), and fruits, seeds, and nuts.

Anatomically, the digestive tracts of humans and our fellow great apes are very similar. In fact, our DNA is very similar. So, what do they eat? Largely vegetarian diets with high greens and fruit consumption. Just largely vegetarian? Yeah, chimpanzees have been known to hunt, kill, and eat prey. But the intake of food of animal origin by chimpanzees is at a very low level, with only 1.7% of chimp stools providing evidence of animal food consumption—based on eight years of work, collecting nearly 2,000 fecal samples. So, even the most carnivorous of great apes appear to eat like a 98% plant-based diet. We may be closest to the diet of bonobos, one of the less known great apes, who eat nearly exclusively plant-based diets as well.

Even our Paleolithic hunters and gatherers must have been done an awful lot of gathering to get upwards of 100 grams of fiber a day. So, what would happen if you put people on an actual Paleolithic diet? Not a supermarket-checkout-aisle-magazine Paleo diet, or some caveman blogger diet, but an actual 100+ grams of fiber diet. Or even better, a Miocenic diet, taking into account the last 20 million years of evolution since we split with our common great ape ancestors.

David Jenkins and colleagues gave it a try. They tested the effects of feeding a diet very high in fiber. We’re talking 150 grams a day, far higher than the recommended 20 to 30 grams a day, but 150 was like what populations in rural Africa used to eat—populations almost entirely free from many of our chronic killer diseases like colon cancer and heart disease.

Look at this. They were not messing around. So, what did you have for lunch today? Oh, a pound of cabbage. Certainly, just eating a lot of fruits/veggies/nuts can’t be very satisfying. No, it got the maximum satiety rating, three out of three by every one of the ten subjects, it appears. Why? Because all the diets were designed to be weight-maintaining; they didn’t want weight loss to confound the data. And so, to eat a full day’s calories of whole plant foods, they had to shovel in 11 pounds of food a day, not surprisingly resulting in some of the largest bowel movements ever recorded in the medical literature—in the men, exceeding a kilogram per day. You know how some people on weight-loss diets lose two pounds a week? They dropped two pounds in one day.

But that’s not the only record-breaking drop. A 33% drop in LDL cholesterol within just two weeks. Even without any weight loss, bad cholesterol levels dropped a third within two weeks—that’s the biggest drop I’ve ever seen in any dietary intervention—better than a starch-based vegetarian diet, better than a low-saturated fat American Heart Association-type vegetarian diet. A cholesterol reduction equivalent to a therapeutic dose of a statin drug. So, one needs to take a drug to get our cholesterol levels down to where they’d normally be if we ate a more natural diet.

We’ve been eating 100 grams of fiber every day for millions of years. Similar to what’s eaten by populations who don’t suffer from many of our chronic diseases. Maybe this shouldn’t be called a very high fiber diet. Maybe what we eat should be considered very low; an extremely fiber-deficient diet. Maybe it’s normal to eat 100 grams of fiber a day. Maybe it’s normal to be free of heart disease; maybe it’s normal to be free of constipation, and hemorrhoids, and diverticulitis, and appendicitis, and colon cancer, and obesity, and type 2 diabetes, and all the other diseases of Western civilization.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

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