Are Humans Herbivores?

Note: this is one of my oldest posts, written when I was 19. While this post is certainly not the “fresh take” on the natural diet of humans that I probably thought it was at the time, it still has solid information, so I decided to leave it up! 

This is part three of my series on veganism. Follow the links to read part one and part two!

One source of disagreement between vegans and meat eaters is the question of what humans are supposed to eat. Many vegans claim humans are herbivores, while meat-eaters assert that humans are omnivores. So what are we, anyways? Herbivores? Carnivores? Omnivores? Most of you probably know the answer to this already, but it doesn’t hurt to look at the evidence. To answer this question, it makes sense to start with what humans eat in their ‘natural habitat,’ when they’re completely undisturbed by modern civilization. As such, this post will look at what traditional hunter-gatherer cultures ate!

One of the best sources of evidence for what humans eat in their natural habitats is Weston A. Price’s book Nutrition and Physical Degeneration. His name gets tossed around quite a bit in the ancestral health community, so I was already somewhat familiar with his work, but I had never actually read his book. I figured it was high time I ordered a copy and read it for myself, and I’m glad I did! If you’re at all interested in nutrition and haven’t read Nutrition and Physical Degeneration, I’d highly recommend that you do. The amount of wisdom contained in that book is absolutely incredible, and it’s a testament to the power of food in determining the health of individuals and communities.

Anyways, Weston Price traveled all over the world to study the diet and health of native populations to determine the cause of poor health in modern societies. Being a dentist, he mainly recorded the rates of tooth decay and the quality of dental arch and face formation. Those markers might seem relatively insignificant at first glance, but dental health and face structure is surprisingly indicative of overall health. When a native population adopts a modern diet of processed foods, tooth decay is quick to follow, with other degenerative diseases such as diabetes and obesity coming soon after. You could say that dental health is the proverbial canary in the coal mine; when people start getting tooth decay and malformed dental arches, you know something’s not right with their diet.

Some of the groups he looked at included the Swiss, Gaelics, Eskimos, North American Indians, Melanesians, Polynesians, African tribes, Aborigines of Australia, Malay tribes, the Maori, and isolated peoples in Peru. There’s a ton of data in that book (plus a ton of pictures of teeth), so I won’t review it all in-depth, but he did find some trends that are pretty significant to the question we want to answer. Of all the native people he came into contact with, the vast majority included some type of animal food in their diet. During a trip to the South Sea Islands, he actually made a special effort to find native people who lived entirely on plant foods, but he couldn’t find any. The people living in the interior of the island didn’t have ready access to seafood, and subsisted mostly on plants, but they weren’t vegan. The people had discovered that they couldn’t go longer than three months without some form of seafood and still remain in good health, so they went to great lengths to obtain seafood on a regular basis, even while they were at war with the coastal tribes.

Now, the fact that humans in a natural setting consistently eat both plants and animals (even when there isn’t ready access to animal products) is pretty strong evidence in favor of the idea that humans are naturally omnivores. I mean, wild animals in their natural environment tend to eat what they’re supposed to eat: cats hunt and eat small prey, birds eat bugs and seeds, cows graze. You probably wouldn’t see a cat trying to break open a pinecone to get the pine nuts, or a cow chasing down a rabbit for lunch. If other animals in a natural setting eat the diet that their bodies are adapted for, it makes sense that humans would too.

But what makes the argument much stronger is the fact that humans are healthy as omnivores. In fact, when the native people groups strayed towards a more plant-focused diet, their dental health tended to decline. Weston Price studied nearly 30 different African tribes, and he found the lowest percentage of tooth decay and facial irregularity in the tribes who depended heavily on animal products and marine life for their food. For example, the Masai eat a diet primarily of meat, blood, and milk from the cattle they raise, along with some fruits and vegetables. He examined 88 different people and found only 4 with tooth decay, affecting a total of 10 teeth, or 0.4% of all the teeth he examined. When he studied the Muhima Tribe, with diets very similar to the Masai, he couldn’t find a single tooth with tooth decay. On the other hand, the Kikuyu were primarily an agricultural people, eating sweet potatoes, corn, beans, bananas, millet, and Kafir corn. Their rates of tooth decay were much higher than that of the Masai at 5.5%. Now keep in mind, these people don’t have dentists and toothbrushes. The fact that they could get away with even that amount of tooth decay is pretty incredible, especially in the context of our society’s regular 6-month dental checkups. But the trend in favor of groups who ate more animal products shouldn’t be ignored.

I mentioned earlier that most of the groups Weston Price studied ate animal products. It’s important to note that he did find some groups living on vegan diets, but they did so purely for religious reasons. Within a generation, these people groups experienced significant levels of tooth decay and abnormal dental arches, indicating that their plant-based diet wasn’t sufficient for good health. It seems that the hill people of the South Sea Islands were correct in their assessment that they couldn’t be healthy without at least some animal products.

To me, all of this evidence points clearly to the conclusion that humans are omnivores. Native people groups overwhelmingly eat omnivorous diets, and the healthiest groups are those who consume more animal products. By contrast, the groups who attempt to subsist entirely on plants for religious reasons show a marked decrease in their health within one generation.

But while the anthropological evidence is strong, I would be remiss to ignore another huge evidence base: biology. Based on the information in this post, I think it’s safe to say that humans are naturally omnivores, and are generally healthiest on a diet that includes both plants and animals, but it would be helpful to know the biological mechanisms that account for this observation. That will be the focus of my next post, and it will help us answer another question: is it possible for humans to be healthy on a vegan diet? Stay tuned!