There is a widespread belief that our ancestors, the Hunter-Gatherers, were fundamentally carnivores (hunters) and, to a lesser extent, plant-eaters (gatherers). That belief has trended into two popular animal-based diets: Paleo and Ketogenic. In other words, an animal-based, high-fat, low-carb diet is preferable over a plant-based, low-fat, high-carb diet.
My research has uncovered some critical data regarding the diet of our ancestors. Most importantly, hunter-gatherers consumed between 100 and 150 grams of plant fiber daily. Since fiber is found only in plants, how is that possible if they mainly ate meat? It doesn’t compute. One hundred grams of fiber is a staggering amount when you consider 1) present nutrition guidelines, which recommend 25–38 grams daily, and 2) the average person in Western countries consumes only 15 to 20 grams.
Note: Botanists estimate there are approximately 50,000 species of wild plants that humans can eat, while only 150 to 200 edible plants are regularly cultivated worldwide. Just 12 crops presently provide 80% of the world’s calories. Conclusion: Since our ancestors did not farm, they must have consumed in abundance a variety of edible plant options presently unknown to us.
HOW OFTEN DID OUR ANCESTORS EAT MEAT?
The frequency with which hunter-gatherers ate meat varied widely based on the environment, season, and availability of plant foods. Still, meat was generally consumed less frequently than modern assumptions suggest.
The following anthropological, archeological, and biological data are helping to reshape our understanding of how the human diet evolved:
1. Hunter-Gatherers Today: Living Clues from the Past
Since they diverged from their human ancestors 100,000 to 200,000 years ago, anthropologists have long studied modern hunter-gatherer societies to understand how human eating habits evolved. Examples are:
The Hadza of Tanzania
Subsist on wild tubers, berries, baobab fruit, honey, and game meat
Estimated fiber intake: 100 to 150 grams per day
Much of the fiber comes from resistant starches, a fermentable fiber beneficial to gut bacteria.
“The Hadza diet offers a living window into human dietary evolution.”
— Pontzer, H. (2021). Burn: The Misunderstood Science of Metabolism
The !Kung San (Bushmen) of Southern Africa
Consume large amounts of fibrous plant foods such as tubers, mongongo nuts, seeds, wild melons, and leafy greens.
Also exhibit seasonally variable but consistently high fiber intake
These diets radically differ from the modern world’s refined, fiber-depleted foods.
2. Ancient Feces and Fossils Tell the Tale
Paleoanthropologists have studied coprolites (fossilized human feces) and dental calculus (hardened plaque) from prehistoric humans:
Analyses reveal significant quantities of undigested plant fibers, seeds, and phytoliths (tiny silica structures from plants)
Stone tools show residues of tubers, grains, and legumes, all rich in fiber
“Prehistoric diets were dominated by wild plant foods—high in fiber and low in energy density.”
— Henry, A.G. et al. (2011). Science, 334(6053), 1264–1266
3. Wild Foods vs. Modern Foods: A Fiber Gap
Wild plants, especially roots, leaves, and fruits, are dramatically more fibrous than their domesticated counterparts. Since these foods are low in calories per gram, early humans had to eat a large quantity of these plants to meet their energy needs, resulting in naturally high fiber intake.
4. Our Gut Was Built for Fiber
Humans have a gut design that reflects millions of years of fiber-rich diets:
A large, fermentation-friendly colon produces short-chain fatty acids (SCFAs) from fiber
SCFAs regulate inflammation, improve immune function, and help maintain metabolic health
“The large human colon is a legacy of high-fiber foraging.”
— O’Keefe, S.J.D. (2016). American Journal of Clinical Nutrition, 104(6), 1631–1638
Contrast this with modern ultra-processed, high-fat/low-carb diets, which are not only low in fiber but often actively disrupt the health of the gut microbiome.
So, did our Ancestors Consume Over 100g of Fiber Daily?
It’s highly probable, based on the following:
- Studies of modern hunter-gatherers
- Fossilized human waste and dental residues
- Nutritional analysis of wild plants
- Evolutionary adaptations in our digestive system
WHY IT MATTERS TODAY
Fiber isn’t just about regularity; it is the foundation of immune health, inflammation control, metabolic balance, and longevity.
While we don’t have to go live in a faraway grassland or prairie to improve our health, we can take a cue from our evolutionary Past: eat more whole, unprocessed plant foods and aim for 50–75 grams of fiber daily as a realistic modern goal. It will not only increase our lifespan and healthspan, but this good nutrition habit will help us avoid chronic gut diseases such as Inflammatory Bowel Disease (IBD), Irritable Bowel Syndrome (IBS), Celiac Disease, Ulcerative Colitis, Diverticulitis, Constipation, Hemorrhoids, and Colon Cancer.
References
1. Pontzer, H. (2021). Burn: The Misunderstood Science of Metabolism. Penguin Press.
2. Henry, A.G., Brooks, A.S., & Piperno, D.R. (2011). “Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets.” Science, 334(6053), 1264–1266.
3. O’Keefe, S.J.D. (2016). “Diet, microorganisms and their metabolites, and colon cancer.” American Journal of Clinical Nutrition, 104(6), 1631–1638.
4. Eaton, S.B., Konner, M., & Shostak, M. (1988). “Stone agers in the fast lane: chronic degenerative diseases in evolutionary perspective.” American Journal of Medicine, 84(4), 739–749.
5. Schnorr, S.L. et al. (2014). “Gut microbiome of the Hadza hunter-gatherers.” Nature Communications, 5:3654.
