Humans are herbivores

We think we are omnivores, but evolution, anatomy, and physiology point to Herbivory

Many people think of humans as omnivores, designed to eat a diet with a substantial contribution of nutrients coming from both plants and animals. However, there is strong evidence that humans are in fact herbivores, meaning that the overwhelming majority of their diet should be comprised of plants. This common misunderstanding may well be the leading cause of premature human death worldwide.

What most think of as omnivores, for instance, bears, dogs, raccoons and so on, are in a lineage that descended from dog-like carnivores and should be thought of as carnivores modified to be omnivorous, distinct from herbivores that have been modified to be omnivorous.

Katharine Milton, from the University of California Berkley’s Department of Environmental Science, Policy and Management says “there seems general agreement that the ancestral line leading to apes and humans was markedly herbivorous” and that for most of our approximately 150,000-year existence our diet appears to have been based on plants.

Milton has also pointed out “the lack of evidence supporting any notable diet-related changes in human nutrient requirements, metabolism, or digestive physiology relative to those of great apes.”

Iris F.F. Benzie, D.Phil. at The Hong Kong Polytechnic University, Kowloon argued that we lost the metabolically costly ability to synthesize vitamin C because of the abundance in our ancestors’ diets. Scientists can examine plaque on and isotopes in ancient teeth, fossilized waste and more to learn about what our ancestors ate. Prof. Benzie estimates that our ancestors 10,000 years ago ate around 10 times more vitamin C and fiber than we do today.

William Clifford Roberts, MD and former Editor in Chief of The American Journal of Cardiology argued in a Letter from the Editor that humans are anatomically and physiologically herbivores. Herbivores, he says, have hands or hoofs, flat teeth, long intestines, sweat to cool the body, sip water (cheeks and lips facilitate the creation of a vacuum in the mouth), and get our vitamin C from our diet. Carnivores have claws, sharp teeth, short intestines, pant to cool themselves, lap up water (because they lack cheeks and lips), and make their own vitamin C.

Plants have tough cell walls made of fiber, sugar molecules bonded together, that provides protection and rigidity without using cholesterol. No mammal produces an enzyme that can digest fiber. Instead, herbivores developed a mobile jaw and flat teeth that slide past each other horizontally to chew their food and crush the cell wall, plus a long digestive tract to provide time to extract nutrients.

Carnivore’s food, animal cells, have a flexible, fat-based cell membrane embedded with cholesterol to give it some rigidity. Animal cells are easily digestible but the bones in animals are not, so carnivores have strong stomach acid and a short digestive tract. No chewing is necessary beyond reducing the size of the chunks enough to swallow because there’s no cell wall. As a result, carnivores like cats and omnivorous carnivores like the bear and dog can only move their jaw up and down; their molars slide past each other vertically like a pair of scissors.

Animals like rabbits, cows, and humans can easily move their lower jaw side to side, and most experts agree that humans have generalized herbivorous dentition that, if anything, is best suited for eating seeds.

Heart disease is the leading cause of death in the world according to the World Health Organization. It’s also the leading cause of death in the U.S. according to the CDC, which states that “diets high in saturated fats, trans fats, and cholesterol have been linked to heart disease and related conditions, such as atherosclerosis,” the mechanism underlying most heart disease. Trans-fats and cholesterol are only found in animal foods.

Dr. Roberts points out that “it is virtually impossible… to produce atherosclerosis in the dog” even when feeding them around 200 times the average amount of cholesterol Americans eat daily. Herbivores like rabbits on the other hand “rapidly develop atherosclerosis” if fed comparatively small amounts of fat and cholesterol.

Cholesterol is made from fat, something most plants have little of. Herbivores have evolved to be efficient at producing adequate cholesterol from a low-fat diet. They also have mechanisms that hold onto and recycle fat and cholesterol. When herbivores eat animal-foods, the excessive fat and cholesterol facilitate the formation of atherosclerotic plaques in artery walls.

There is an overwhelming amount of evidence that humans aren’t carnivores like cats or omnivores like dogs but are in fact primarily herbivores. It’s recommended we eat a diet low in saturated fat, trans-fat and cholesterol because of atherosclerosis, a disease that herbivores are susceptible to. The approximately 20-million-year evolutionary lineage of great apes is markedly herbivorous. Our digestive anatomy and physiology, nutrient requirements, and metabolism do not appear to differ notably from the other great apes or herbivores generally, and for most of the approximately 150,000-year history of our species we appear to have eaten mostly plants.

As ever-increasing evidence illuminates this issue, it’s time for humans to consider a change to a plant-based diet.

Sean can be reached at [email protected]

60 replies

  1. Alfred Maloney

    I am a carnivore. I spend about a half hour a day eating. If I was a herbivore I would be eating all day like my ape cousins. Meat and fish are very nutritiet rich. Plants are not bioavailabile and have antinutrients. Animals and fish are nutritiet rich with no antinutrients. Please google antinutrients in food and bioavailability of food. But you have to dig deep because the food and drug industry control google.

  2. Pigstowidget

    Maybe the discussion should be about what we can do now. It seems from what I've read that a wholefood plant-based diet is extremely healthy, for those that can get it. Given that 80 billion land animals are cruelly brought into existence, kept and then killed each year then surely choosing a wholefood plant-based diet is the best option? And also given that we know that animal agriculture is one of the leading causes of climate change, then surely we should be doing this one thing to save life on earth? It doesn't matter what happened in the past, or what our ancestors did, but what can we do now? The world is in a mess, not least because of the way we treat non-human life.

  3. ThePaganSun

    This article like most of these idiot vegan comments are RIDICULOUS at best and outright DANGEROUS at most. Get this through your idiot heads: Humans are BIOLOGICALLY OMNIVORES!!! We don't have sharo teeth and fangs like cats but we also don't have hooves and chew cud or eat grass, you dumbasses! In fact, our bodies digest meat and animal protein far easier than plants. And most herbivores don't eat the vegetables and fruits but rather leaves. So no, we are NOT herbivores!! Enough of your ridiculous double-standards. And without supplements and fortified foods, veganism wouldn't be sustainable in the least so spare us your bullcrap of how it's "more natural." It's not! What you do with your own deluded bodies is one thing but STOP making such deluded and easily debunked claims about the rest of us. Humans can digest meat. We CANNOT digest cellulose. Get that through your idiot, deluded, pansy heads.

  4. Marielou

    We are biologically Herbivores. Herbivores can still consume meat. Just like Apes. But! Only small quantities. When the amount of meat (and other animal products) in our diet increases that is when we start seeing serious cardiovascular diseases and cancer development. All we need to do is follow a plant based diet and have a small (very small) amount of animal products if we choose to. However, animal products are 100% not necessary to our diet while plants are. Let's not forget that we evolved to have symbiotic relationship with bacteria that ferment and consume fiber (lactobacillus, bifidobacteria etc).

    1. lana

      Consider googling the importance of cellulose in the human diet. Maybe look into how difficult meat is for humans to digest, as well. Might clear up your misconceptions.

  5. Tejas das

    Yes, you are absolutely correct even Lord krishna says in bhagavad gita "Annad bhavanti bhutani" All humans subsist on food grains. God has alloted a vegeterian diet for us and if we trangress this law then we are liable to be punished but foolish people do not believe in scriptures and act whimsically and thus will be punished. Thanks for writing such a nice article. Hare krishna.

  6. Michael Morelli

    So, if mankind is originally herbivores, why have skeletal remains of the earliest humans shown that they consumed meat as well as vegetables and legumes? If mankind were designed as herbivores, why do we possess the apex predator traits (front eyesight, incisors and canine teeth, increased intelligence)? As was once stated, 'Eating meat is an instinct, being a vegetarian is a choice.'.

  7. Kyle

    This whole article is FALSE. If we were herbivores we would not have a simple gut. Herbivores need a super long gut because plants are low in calories and therefore to get proper intake they have to eat a ton! In case you haven’t noticed, some of the largest animals on earth are herbivores. Also we do not have the proper enzymes to break down the majority of plants. Take that vegans! For example, the shell of corn, beans, peas, and skin of fruits like tomatoes and peppers, we cannot break down and it comes out in our poop. The insides we get the nutrients though. Cows don’t even produce the correct enzymes to break down cellulose. Which is why we shouldn’t feed cows corn, but grass instead since it’s easier to digest. They have to have their gut bacteria make the enzyme. Humans don’t have the enzyme or the proper gut bacteria. Also there are vital nutrients we need that come only from meat. And if you say “take your supplements” they are first off not as effective as the meat and did they have that thousands of years ago? Heck no. Now, do we eat the right amount of meat as biologically proven omnivores based on our gut and teeth and so much more? God no. We eat too much, at least in America. We should be toning back the meat we eat and eating different kinds. This is honestly why fish and occasional game meat would be the healthiest options. Although our bodies evolve based on what we eat like how they evolved when we started farming grains, our diets are indeed changing faster than our genetics can so I understand why people are going vegan and vegetarian because of health issues. However, we are meant to and kind of require meat in our diet so at least eat eggs and fish and maybe the occasional red meat because heme-iron is so much easier to digest than that of which is in greens. Overall, this is false and just vegan propaganda. Thanks for coming to my TED Talk.

  8. YY

    What difference does it make what type of jaw and teeth an animal has for what type of food they should eat? What about a jawless carnivorous hagfish, or a toothless carnivorous spider, or a massive jaw and toothed herbivorous hippopotamus?

  9. blard

    Why do we have canine teeth then? Our teeth suggest a more omnivore diet. It's true some people do much better on a plant based diet while others do better on a meat based diet. NOT ALL PEOPLE ARE BORN EQUAL.

  10. Chloe

    My hubby and I have been vegan for 12 years and so far we're feeling great. We've had our bloodwork done several times-and our B12 levels were always great and we never had Anemia. Our vit D levels were always great also. Dr. Neal D. Barnard, Dr. Joel Fuhrman, Dr Michael Greger & Dr John A. McDougall are vegan drs....look at there videos and websites.

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