Humans are naturally plant eaters

 

 

Humans are naturally plant-eaters

 

 

according to the best evidence: our bodies

 

by Michael Bluejay • June 2002 • Updated March 2012
 

A fair look at the evidence shows that humans are optimized for eating plant foods, according to the best evidence: our bodies.  We're most similar to other plant-eaters, and drastically different from carnivores and true omnivores.1,2,3  Those who insist that humans are omnivores, especially if their argument is based on canine teeth, would do well to look at what the evidence actually shows.  We'll cover that below.
 

I first wrote this article many years ago, but since then Milton Mills, M.D. wrote an excellent paper which covers the anatomy of eating, so let's skip right to my table-ized summary of his research:

Humans are biologically herbivores
 

 
Carnivores
 
Omnivores
 
Herbivores
 
Humans
 
Facial muscles
 
Reduced to allow wide mouth gape
 
Reduced
 
Well-developed
 
Well-developed
 
Jaw type
 
Angle not expanded
 
Angle not expanded
 
Expanded angle
 
Expanded angle
 
Jaw joint location
 
On same plane as molar teeth
 
On same plane as molar teeth
 
Above the plane of the molars
 
Above the plane of the molars
 
Jaw motion
 
Shearing; minimal side-to-side motion
 
Shearing; minimal side-to-side motion No shear; good side-to-side, front-to-back
 
No shear; good side-to-side, front-to-back
Major jaw muscles
 
Temporalis
 
Temporalis
 
Masseter and ptergoids
 
Masseter and pterygoids
 
Mouth opening vs. head size
 
Large
 
Large
 
Small
 
Small
 
Teeth: Incisors
 
Short and pointed
 
Short and pointed
 
Broad, flattened and spade-shaped
 
Broad, flattened and spade-shaped
 
Teeth: Canines
 
Long, sharp, and curved
 
Long, sharp and curved
 
Dull and short or long (for defense), or none
 
Short and blunted
 
Teeth: Molars
 
Sharp, jagged and blade-shaped
 
Sharp blades and/or flattened
 
Flattened with cusps vs. complex surface
 
Flattened with nodular cusps
 
Chewing
 
None; swallows food whole
 
Swallows food whole and/or simple crushing
 
Extensive chewing necessary
 
Extensive chewing necessary
 
Saliva
 
No digestive enzymes
 
No digestive enzymes
 
Carbohydrate digesting enzymes
 
Carbohydrate digesting enzymes
 
Stomach type
 
Simple
 
Simple
 
Simple or multiple chambers
 
Simple
 
Stomach acidity with food in stomach
 
≤ pH 1
 
≤ pH 1
 
pH 4-5
 
pH 4-5
 
Length of small intestine
 
3-6 times body length
 
4-6 times body length
 
10-12+ times body length
 
10-11 times body length
 
Colon
 
Simple, short, and smooth
 
Simple, short, and smooth
 
Long, complex; may be sacculated
 
Long, sacculated
 
Liver
 
Can detoxify vitamin A
 
Can detoxify vitamin A
 
Cannot detoxify vitamin A
 
Cannot detoxify vitamin A
 
Kidney
 
Extremely concentrated urine
 
Extremely concentrated urine
 
Moderately concentrated urine
 
Moderately concentrated urine
 
Nails
 
Sharp claws
 
Sharp claws
 
Flattened nails or blunt hooves
 
Flattened nails
 
From The Comparative Anatomy of Eating (PDF), by Milton R. Mills, M.D.
 

The details are in Mills' paper (PDF).  The rest of this article covers mostly angles not in that paper, and since it's long, here's a condensed version:
 

  • The anatomical evidence tells us that we're optimized for eating almost exclusively plant foods.  The only way to come to another conclusion is to ignore the bulk of the anatomical evidence, which is what my critics do.  (They either use inferior evidence, such as disputed assumptions about the prehistoric diet, or they cherry-pick the anatomical evidence while ignoring the bulk of it.)
  • The animals most similar to us, the other primates, eat an almost exclusively vegan diet.
  • "Omnivore" doesn't mean 50% plants and 50% animals.  Many consider chimpanzees to be omnivores but 95-99% of their diet is plants, and most of the rest isn't meat, it's termites.  If humans are omnivores, then the anatomical evidence suggests that we're the same kind:  the kind that eats almost exclusively plant foods.
  • Saying we're omnivores because we're capable of eating meat is just silly.  We're capable of eating cardboard, too.  And by the "capable" argument, then cats are omnivores, since nearly every commercial cat food has plant ingredients.  (Check the label.)  Nobody would ever make the argument that cats are omnivores based on what they're capable of eating.  But they sure make that argument for humans, enthusiastically.
     
  • Our so-called "canine teeth" are "canine" in name only.  Other plant-eaters (like gorillas, horses, and hippos) have "canines", and chimps, who are almost exclusively vegan, have massive canines compared to ours.  (See picture below.)
     
  • Our early ancestors from at least four million years ago were almost exclusively vegetarian. (source, article #5)
     
  • Among animals, plant-eaters have the longest lifespans, and humans are certainly in that category (and yes, this was true even before modern medicine).
     
  • We sleep about the same amount of time as other herbivores, and less than carnivores and true omnivores.

     
  • The most common cause of choking deaths is eating meat. (source)  Real carnivores and omnivores don't have that problem.

The meat-eating reader already has half a dozen objections to this before s/he's even read the rest of the article, and I will address those objections specifically, but first let me address them generally: It's human nature to want to feel that what we're doing is right, proper, and logical. When we're confronted with something that suggests that our current practices are not the best ones, it's uncomfortable. We can either consider that our choices may not have been the best ones, which is extremely disturbing, or we can reject that premise without truly considering it, so that we don't have to feel bad about our actions. That's the more comfortable approach. And we do this by searching our minds for any arguments we can for why the challenge must be wrong, to justify our current behavior. This practice is so common psychologists have a name for it: cognitive dissonance.

Think about that for a moment: Our feeling that our current actions are correct isn't based on our arguments. Rather, our actions come first and then we come up with the arguments to try to support those actions. If we were truly logical, we'd consider the evidence first and then decide the best course of action. But often we have it in reverse, because it's too difficult to accept that we might have been wrong.

 

Vegan bodybuilders shatter the myth that vegans are skinny and malnourished.
This is particularly true when it comes to vegetarianism. It's easy to identify because the anti-vegetarian arguments are usually so extreme, compared to other kinds of discourse. A person who would never normally suggest something so fantastic as the idea that plants can think and feel pain, will suddenly all but lunge for such an argument when they feel their meat-eating ways are being questioned, and they're looking for a way to justify it.  That's psychology for you.
  

I used to be in the same position as most readers probably are now.  Long ago my eating habits were challenged by a book I ran across in the library. I didn't want to consider it fairly, because I wanted to keep eating meat. I'd grown up eating it, and I liked it. So I came up with various weak defenses to justify my behavior. But deep down I knew I was kidding myself, and practicing a form of intellectual cowardice. Eventually I knew I had to consider the arguments honestly.

So I challenge you: stop trying to figure out ways that I "must" be wrong even before you've bothered to read the rest of this article. Instead, read it, and actually consider it rather than reflexively trying to come out with ways to dismiss it out of hand. You can certainly still disagree after you've considered all the evidence -- but not before.

Most meat-eating readers will find it necessary to try to defeat me, at least in their minds, so let's agree that that would mean providing more and better evidence for your position. One does not win the argument by making a single point, as most of the critics who email me seem to think. The evidence favoring a plant diet for humans is clear, convincing, and overwhelming. There is definitely some evidence for the other side, to be sure, but it's simply not nearly as strong. While you think this would be obvious, I mention it because my critics seem to believe that whoever makes the fewest and weakest points has presented the most convincing case. They somehow seem to believe that all the evidence I present somehow vanishes into thin air when they present their lone argument.
 

In graphical form, it goes like this:

Evidence that humans are primarily plant-eaters
Evidence to the contrary
 

Many believe that lunging at at the minority of evidence in the red box makes their position compelling. But it doesn't. The only way to make that position compelling is to present more and better evidence, not to pretend that the green box doesn't exist.
 

 

The most common counter-arguments

 


Chimpanzee: Pretty amazing canines for an animal that's as much as 99% vegetarian (and whose main non-veg food isn't meat, it's termites). (Source: Creative Commons)
"Humans have canine teeth. End of story." 

The truth is our so-called "canine teeth" are canine in name only. Humans' "canine teeth" are unlike the canine teeth of actual canines, which are really long and really pointed.  Our teeth are absolutely not like theirs. In fact, other vegetarian animals (like gorillas, horses, hippos, and chimpanzees) possess the same so-called "canine" teeth, which are often used for defensive purposes rather than for eating.  Check out the chimpanzee picture at right, and consider that chimps' diets are up to 99% vegetarian (and what litle non-vegetarian food they eat usually isn't meat, it's termites).  And remember that we're most similar to chimps than to any other animal.

John A. McDougall, M.D., has a good take on this:
 
Our dentition evolved for processing starches, fruits, and vegetables, not tearing and masticating flesh. Our oft-cited "canine" teeth are not at all comparable to the sharp teeth of true carnivores.  I lecture to over 10,000 dentists, dental hygienists, and oral specialists every year, and I always ask them to show me the “canine” teeth in a person’s mouth – those that resemble a cat’s or dog’s teeth – I am still waiting to be shown the first example of a sharply pointed canine tooth.

If you have any doubt of the truth of this observation then go look in the mirror right now – you may have learned to call your 4 corner front teeth, “canine teeth” – but in no way do they resemble the sharp, jagged, blades of a true carnivore – your corner teeth are short, blunted, and flat on top (or slightly rounded at most).  Nor do they ever function in the manner of true canine teeth.  Have you ever observed someone purposely favoring these teeth while tearing off a piece of steak or chewing it?  Nor have I.  The lower jaw of a meat-eating animal has very little side-to-side motion – it is fixed to open and close, which adds strength and stability to its powerful bite.  Like other plant-eating animals our jaw can move forwards and backwards, and side-to-side, as well as open and close, for biting off pieces of plant matter, and then grinding them into smaller pieces with our flat molars.

 

I love the canine argument because the people who make it place so much importance on it, insisting that humans having canines immediately wins the whole argument, all by itself, case closed! But when they discover that they were wrong, then suddenly the canine issue really wasn't so important to them after all, and they simply move on to their next misconception, as though their previous argument never happened. That really lays their motivations bare: They were never really interested in evaluating the evidence, they were only interested in being right. But really, if someone thinks that canine teeth are the be-all and end-all of the herbivore vs. omnivore debate, then when they find out that they're wrong about teeth, that ought to tell them something. But does it ever? Nope.  If you want an evidence of bias, there you have it.
 

"Humans have always eaten meat."

No, we haven't. Just because we assume that humans have always eaten meat doesn't make it true. I'll provide evidence for this shortly. But what's more important is that unlike other animals, humans can act outside of instinct. That means that if early humans did eat meat, they were simply making an interesting choice, not doing what their biology favors. We really have to look at our digestive system to get the best evidence for what we're optimized for eating, not what some humans chose to eat. Otherwise, thousands of years from now anthropologists might conclude that eating McDonald's is natural because humans circa 2011 used to eat a lot of it.

I'll cover the early human diet in more detail momentarily.

"We're capable of eating meat, therefore we're omnivores. Case closed."

Okay, fine, then cats are omnivores, too. ("Case closed.")  Commercial cat foods, both wet and dry, contain things like rice, corn, and wheat. In fact, some people feed their cats a pure vegan diet with no meat at all.

But of course, cats are true carnivores. We don't call them omnivores just because they'll eat things contrary to what nature intended. That would be silly. No one makes that argument for cats. But they make it for humans, enthusiastically. However, they can't have it both ways: Either we don't assume humans are omnivores just because we can eat meat, or we apply the same standard to other animals and conclude that cats are omnivores, too. Which is it?

"Humans are omnivores."

"Omnivore" doesn't mean 50% plants and 50% animals.  Many consider chimpanzees to be omnivores but 95-99% of their diet is plants, and most of the rest isn't meat, it's termites.  If humans are omnivores, then the anatomical evidence suggests that we're the same kind:  the kind that eats almost exclusively plant foods.  And if an omnivore is an animal that is capable of eating both plants and animals, and ever does so, then sure, we're omnivores, but then again, so are cats. (See above.) A true omnivore would have a body optimized for eating both plants and animals. With non-humans we can look at what they eat in the wild to figure out their preferred diets, but humans lost our instincts long ago, so we can look only at our anatomy and digestive systems. And that evidence is compelling.

"You're not a doctor, therefore you must be wrong. Yay, I win!"

It's funny, the people making this charge aren't doctors either, but somehow they don't feel that being a doctor is neccessary to advance their positions.

In any event, bona-fide doctors say the same kinds of things I say in this article. For example, here's an article by Dr. John McDougall and one by Dr. Milton R. Mills (both M.D.'s). I wonder whether the people who send me hate mail about this article and tell me I'm an idiot would feel just as confident in telling these two doctors that the doctors are idiots, too?

"Vitamin B12. End of story."

I'm not joking when I tack on "End of story" to the sample counter-arguments. People actually make them that way, literally.

B12 isn't made by animals, it's made by bacteria. (source)  It's found where things are unclean. (And meat is dirty.)  This easily explains why historically it's been easy to get B12, because until recently we didn't live in a sanitized environment. Plants pulled from the ground and not washed scrupulously have B12 from the surrounding soil. (source)  Vegans should take a B12 supplement, not because veganism is unnatural, but because the modern diet is too clean to contain reliable natural sources of dirty B12.

B12 is also found in lakes, before the water is sanitized. (source)  Also, consider that chimpanzees' main non-plant food is termites, and termites are loaded with B12. (source)

Incidentally, our need for B12 is tiny -- 3 micrograms a day. Not milligrams, micrograms. The amount of B12 you need for your entire life is smaller than four grains of rice.  (More on Vitamin B12 from John McDougall, M.D)

"Other primates eat meat."

Hardly. Various sources (below) say that a chimp's diet is 95-99% plant foods, and the primary non-plant food isn't meat, it's termites. We also have to remember that primates are intelligent and can make choices outside of instinct, just like humans do, so the tiny amount of meat they might eat could simply be due to choice, not instinct. The idea that primates are a good example for why humans should eat meat evidently didn't impress the most famous primate researcher of all time, Jane Goodall.  Goodall is a vegetarian.

I cover the primate diet in more detail bolew.

"You're not considering evolution."

Of course I'm not. Humans' hunting skills are relatively recent in our history but evolution takes place over a much longer period of time. In short, we haven't been hunting for long enough for our anatomy to favor a mixed plant-animal diet.

 

But haven't humans always eaten meat?

In a word, no, which we'll discuss in a moment, but first there's something more important: Even if they did, it doesn't matter. That's because people act by idea rather than by instinct. Other animals are programmed to know what food is. We are not. For us, it's learned behavior. Or in some cases, guessed behavior. We can make choices about what we should eat even if that's contrary to good health, as millions prove every day when they eat at McDonald's. If our ancestors ate meat, they were simply being human and making choices rather than acting on instinct. Think about it: Do you really believe that cavemen were true experts about nutrition? If so, what other major decisions about your life would you like to put in the hands of a caveman?
 

Again, the best evidence is to look at our own bodies.  But let's return to the assumption that our ancestors ate meat. I can't think of a better example of a case in which people believe something to be true just because they assume it is. We all grew up thinking that our predecessors were meat-eaters, but where did we get that idea? Is it true just because it's part of our collective consciousness? More importantly, what does the evidence say?

John A. McDougall, M.D., perhaps the most knowledgable expert on the relationship between diet and disease, asserts that our early ancestors from at least four million years ago followed diets almost exclusively of plant foods. (source, article #5)  Many other scientists believe that early humans were largely vegetarian. (See articles byGrande & Leckie and Derek Wall.)  Then there's the newest research:

Robert W. Sussman, Ph.D., professor anthropology in Arts & Sciences, spoke at a press briefing, "Early Humans on the Menu," during the American Association for the Advancement of the Science's Annual Meeting....[E]arly man was not an aggressive killer, Sussman argues. He poses a new theory, based on the fossil record and living primate species, that primates have been prey for millions of years, a fact that greatly influenced the evolution of early man.

"Our intelligence, cooperation and many other features we have as modern humans developed from our attempts to out-smart the predator," says Sussman.... The idea of "Man the Hunter" is the generally accepted paradigm of human evolution, says Sussman, "It developed from a basic Judeo-Christian ideology of man being inherently evil, aggressive and a natural killer. In fact, when you really examine the fossil and living non-human primate evidence, that is just not the case."

Sussman's research is based on studying the fossil evidence dating back nearly seven million years. "Most theories on Man the Hunter fail to incorporate this key fossil evidence," Sussman says. "We wanted evidence, not just theory. We thoroughly examined literature available on the skulls, bones, footprints and on environmental evidence, both of our hominid ancestors and the predators that coexisted with them." ...

But what Sussman and Hart discovered is that Australopithecus afarensis was not dentally pre-adapted to eat meat. "It didn't have the sharp shearing blades necessary to retain and cut such foods," Sussman says. "These early humans simply couldn't eat meat. If they couldn't eat meat, why would they hunt?"

It was not possible for early humans to consume a large amount of meat until fire was controlled and cooking was possible. Sussman points out that the first tools didn't appear until two million years ago. And there wasn't good evidence of fire until after 800,000 years ago.

Bio-Medicine.org, 2006

While some prehistoric peoples hunted animals, that is still a relatively recent development in the long period of human existence. Certainly not long enough for our bodies to have adapted to it from evolution. Here's some evidence: The Maasai in Kenya, who still eat a diet high in wild hunted meats, have the worst life expectancy in the world. (Fuhrman)

In any event, the idea that our ancestors might have decided to mimic other animals and eat meat isn't a particularly compelling argument that it's natural for us to do so. Given that humans act outside of instinct, looking at historical behavior isn't as convincing as looking at anatomy and health effects -- as we'll do in a moment.

 

Considering the other primates

Our closest animal relatives are, of course, the other primates. They provide clues about our ideal diet since our anatomy is so similar. Very few of them eat any significant amount of animals, and those who do typically mostly stick to things like insects, not cows, pigs, and chickens. Jane Goodall, famous for her extensive study of apes while living with them, found that it was very rare for the primates she saw to eat other animals. Critics lunge all over the fact that Goodall discovered that primatesoccasionally eat meat. But the key word here is occasionally. If we ate meat is infrequently as the other primates did, our health would certainly be a lot better. Goodall herself apparently wasn't impressed by primates' occasional eating of meat: Jane Goodall herself is a vegetarian.

 


Chimpanzee: Eats 95-99% plants, and most of the rest is termites (not meat). (Source: Creative Commons)
How slight is the other primates' animal consumption? This article on primate eating habits from Harvardhas a bar graph of all the things that chimps and monkeys eat (Fig. 3), and meat isn't even in the chart. What theydo eat is fruit, seeds, leaves, flowers, and pith. There is a category called "Miscellaneous", which for most species amounts to less than 5% of their diet, and for chimps and redtail monkeys less than 1%. The Honolulu Zoo gives a slighty higher figure, saying that non-plant consumption is 5% of a chimp's diet, but this includes their main non-plant food, termites. (Termites are a good source of vitamin B12, by the way). Craig B. Stanford, Ph.D says, "Chimpanzees are largely fruit eaters, and meat composes only about 3% of the time they spent eating overall, less than in nearly all human societies." (source)  Any way you slice it, their diet is at least 95-99% plants. 

Which brings up another point: The people who hysterically scream at me that chimps are omnivores, besides ignoring that chimps' meat consumption is so small as to be virtually non-existent, never acknowledge that the non-plant foods chimps eat are not the same things humans eat. Chimps do not eat cattle and chickens. And humans don't eat termites. The idea that the meat-laden American diet can be justified because chimps may eat a whopping 5% of non-plant foods, none of it cattle or chickens, and much of it termites, is rather silly.

Let's use the Harvard article's figure for chimps and round it up to a generous 1%. If that were beef -- which it is not -- how much beef would that be? For an adult human, a mere 8 grams a day (about 1/3 of an ounce, or just 0.02 pounds). That's about 1/9th of a medium carrot. Get a carrot, cut it into nine pieces, and each piece then represents the amount of meat you could eat every day to have your diet match that of a chimp. Yes, there you have chimps' overwhelming "omnivorism".

Here's how another writer put it:

"Meat makes up only 1.4% of [chimps'] diet which in any statistical study or analysis would be considered as quantitatively unimportant. In longitudinal studies it has been found that 90% of all kills were by males and as the females rarely hunt they receive a share in return by begging only after she allows him to mate with her.... On rare occasions chimps do eat and kill a baby chimp. So if you follow this argument to its conclusion, humans should kill and eat their babies, meat should only make up 1.4% of the human diet, [and] females should only receive meat by begging for it and allowing the giver to mate with her!" (source)
 

Consider also that even though primates eat meat sparingly, there again it's likely because they're intelligent and like humans are able to make choices to act outside of instinct. As other writers put it, "While chimpanzees are known to kill, this behaviour is not necessarily dietary but ritualistic."  In 2006 the journal Nature published research about how chimpanzees have culture -- behaviors copied from peers rather than being genetic. (See "Case Closed: Apes Got Culture".)

Eugene Khutoryansky who does believe that eating meat is natural, still cautions that the implications of chimps' killing should give us pause:

Eating meat is indeed natural in the sense that other animals do it as well. In fact, it is even done on occasion by our closest living relatives, the chimpanzees. However, there are many other things which are also natural. For example, chimpanzee males sometimes rape the females in their tribe. Chimpanzees sometimes engage in organized warfare against other tribes with which they compete for territory. A chimpanzee male, in a moment of rage, sometimes picks up a nearby infant, and crushes his skull against a rock. And chimpanzees do on occasion eat meat, and they do on occasion engage in cannibalism, in spite of the fact that there is a plentiful supply of food from other sources.

So eating meat is indeed absolutely natural. However, the fact that it is natural does not imply that it is ethically permissible. If we believed that eating meat was ethically permissible simply because other animals did it as well, then this would imply that there is nothing wrong with rape, cannibalism, or infanticide, all of which routinely occurs throughout the animal kingdom. (source)
 

 

What it means to be an omnivore

There is no question that humans are capable of digesting meat.  But just because we can digest animals does not mean we're supposed to, or that it will be good for us.  We can digest cardboard.  But that doesn't mean we should.  As I mentioned earlier, commercial cat foods typically contain rice, corn, and wheat.  But of course, cats are true carnivores.  We don't call them omnivores just because they'll eat things contrary to what nature intended.  That would be silly.  No one makes that argument for cats.  But they make it for humans, enthusiastically.

McDougall explains how the ability to digest animal foods didn't hurt our survival as a race, although it takes a toll on our lifespan:

"Undoubtedly, all of these [meat-containing] diets were adequate to support growth and life to an age of successful reproduction. To bear and raise offspring you only need to live for 20 to 30 years, and fortuitously, the average life expectancy for these people was just that. The few populations of hunter-gatherers surviving into the 21st Century are confined to the most remote regions of our planet—like the Arctic and the jungles of South America and Africa—some of the most challenging places to manage to survive. Their life expectancy is also limited to 25 to 30 years and infant mortality is 40% to 50%. Hunter-gatherer societies fortunately did survive, but considering their arduous struggle and short lifespan, I would not rank them among successful societies."

The problem with the term "omnivore" is that it's used in different ways. Many folks assert that if a primate ever eats any meat at all, no matter how small or insignificant, then bam! -- they're an omnivore. But cats eat copious amounts of rice, corn, and wheat in commercial cat food, and have far more plants in their diet than meat in primates' diets. So why do these people insist that the piddling, insignificant amount of animal foods consumed by primates makes them omnivores, while cats are carnivores no matter how much plant food they eat?

And once they (think) they've shown that primates are omnivores, they then use this "fact" to justify the huge amount of meat that people eat today. This of course is ridiculous.

A more reasonable definition would be that a true omnivore would routinely eat large quantities of both plants and animals. A creature consuming less than 5% of its calories from animals just doesn't seem very omnivorous to me. (This includes other primates, our ancestors, and traditional Okinawans.) But for the record, if you insist that such creatures are omnivores, then I'll agree with you -- as long as you agree that humans should also eat less than 5% of our calories from animals, just like the other creatures you're basing our "omnivorism" on. And that cats are omnivores, too.

 

Humans lack a desire to eat whole animals

True carnivores (and omnivores) salivate about the idea of eating whole prey animals when they see them. Humans do not. We're interested in eating the body parts only because they've been removed from the original animal and processed, and because we grew up eating them, making it seem perfectly normal. It's amazing how much of a disconnect we've been able to learn about the difference between animals and food. As GoVeg puts it:

While carnivores take pleasure in killing animals and eating their raw flesh, any human who killed an animal with his or her bare hands and dug into the raw corpse would be considered deranged. Carnivorous animals are aroused by the scent of blood and the thrill of the chase. Most humans, on the other hand, are revolted by the sight of raw flesh and cannot tolerate hearing the screams of animals being ripped apart and killed. The bloody reality of eating animals is innately repulsive to us, more proof that we were not designed to eat meat.

Ask yourself: When you see dead animals on the side of the road, are you tempted to stop for a snack? Does the sight of a dead bird make you salivate? Do you daydream about killing cows with your bare hands and eating them raw? If you answered "no" to all of these questions, congratulations--you're a normal human herbivore--like it or not. Humans were simply not designed to eat meat. Humans lack both the physical characteristics of carnivores and the instinct that drives them to kill animals and devour their raw carcasses.

 And here's one of my favorite passages by John A. McDougall, M.D.:

Cats are obligate carnivores (they must live on a diet primarily of meat) and their taste buds reflect this by having abandoned the tongue sensors that respond to sweet-tasting carbohydrates.  Dogs are omnivores (they have retained both kinds of taste buds) those enjoying carbohydrates and amino acids.  Humans tongues respond pleasurably to sweet (carbohydrates), but have lost the taste for amino acids, placing us undeniably in the category of herbivores (plant eaters). 

Many of your friends and family are confused, thinking people are omnivores, needing both meat and plants in their diet.  We only appear to be omnivorous because we have the ability to "doctor up" meat with salt and sauces (barbecue, sweet and sour, marinara, etc.) sufficiently enough to make it palatable.  Prove this for yourself.  The next person you meet head-on who claims meat is "tasty," stop him in his tracks and insist that he eat a large plate of plain, unseasoned, boiled beef or boiled chicken in front of you ; note their displeasure.  Then offer that same meal to the dog or cat and note how eagerly this critter devours the meat.  You would be hard-pressed to find a person who did not enjoy a bowl of perfect, ripe bananas, but try to get your cat to eat this sweet food.  I have a Rottweiler dog named Bodega who is a true omnivore and enjoys bananas as much as meat.  A careful observer notices that an animal's taste buds are no mistake of nature—they clearly define the proper diet that the animal should eat.

 

Comparing humans to other animals

Human physiology is strikingly similar to that of other plant-eaters, and quite unlike that of carnivores.  It is telling that in none of the missives that readers have sent in to argue with me do they ever deny the data in the following table. They simply think that by making some other point (e.g., that humans possess canine teeth) that somehow obliterates the more convincing data in the table.  This is the same table presented at the beginning, but it's important enough that it bears repeating.
 

Humans are biologically herbivores
 

 
Carnivores
 
Omnivores
 
Herbivores
 
Humans
 
Facial muscles
 
Reduced to allow wide mouth gape
 
Reduced
 
Well-developed
 
Well-developed
 
Jaw type
 
Angle not expanded
 
Angle not expanded
 
Expanded angle
 
Expanded angle
 
Jaw joint location
 
On same plane as molar teeth
 
On same plane as molar teeth
 
Above the plane of the molars
 
Above the plane of the molars
 
Jaw motion
 
Shearing; minimal side-to-side motion
 
Shearing; minimal side-to-side motion No shear; good side-to-side, front-to-back
 
No shear; good side-to-side, front-to-back
Major jaw muscles
 
Temporalis
 
Temporalis
 
Masseter and ptergoids
 
Masseter and pterygoids
 
Mouth opening vs. head size
 
Large
 
Large
 
Small
 
Small
 
Teeth: Incisors
 
Short and pointed
 
Short and pointed
 
Broad, flattened and spade-shaped
 
Broad, flattened and spade-shaped
 
Teeth: Canines
 
Long, sharp, and curved
 
Long, sharp and curved
 
Dull and short or long (for defense), or none
 
Short and blunted
 
Teeth: Molars
 
Sharp, jagged and blade-shaped
 
Sharp blades and/or flattened
 
Flattened with cusps vs. complex surface
 
Flattened with nodular cusps
 
Chewing
 
None; swallows food whole
 
Swallows food whole and/or simple crushing
 
Extensive chewing necessary
 
Extensive chewing necessary
 
Saliva
 
No digestive enzymes
 
No digestive enzymes
 
Carbohydrate digesting enzymes
 
Carbohydrate digesting enzymes
 
Stomach type
 
Simple
 
Simple
 
Simple or multiple chambers
 
Simple
 
Stomach acidity with food in stomach
 
≤ pH 1
 
≤ pH 1
 
pH 4-5
 
pH 4-5
 
Length of small intestine
 
3-6 times body length
 
4-6 times body length
 
10-12+ times body length
 
10-11 times body length
 
Colon
 
Simple, short, and smooth
 
Simple, short, and smooth
 
Long, complex; may be sacculated
 
Long, sacculated
 
Liver
 
Can detoxify vitamin A
 
Can detoxify vitamin A
 
Cannot detoxify vitamin A
 
Cannot detoxify vitamin A
 
Kidney
 
Extremely concentrated urine
 
Extremely concentrated urine
 
Moderately concentrated urine
 
Moderately concentrated urine
 
Nails
 
Sharp claws
 
Sharp claws
 
Flattened nails or blunt hooves
 
Flattened nails
 
From The Comparative Anatomy of Eating (PDF), by Milton R. Mills, M.D.
 

 

As another writer said, "The human body was not designed to catch or eat animals. You have no claws. Your teeth do not rend flesh. Your mouth can not seriously wound nor is it made to really get a good bite into an struggling victim like true carnivores can. You are not fit to run fast to catch prey. Meat-eaters have fast enough reflexes to ambush or overtake a victim. You do not. Try catching a pig or a chicken with your bare hands; see what happens."

 

Plant-eaters have the longest lifespans

In general, plant-eating creatures have the longest lifespans. Elephants, horses, and chimpanzees are at the top of the list while lions, tigers, and wolves are about half that. Humans' lifespans are even longer than the elephants etc. (even before modern medicine), providing more evidence that we're in the plant-eating camp.

 

We sleep like herbivores

Carnivores sleep the most, herbivores the least, and omnivores in the middle. Guess which group our own sleep correlates to. Here are some charts from an article in Nature (PDF). They have arbitrarily stuck us (and other primates) in the omnivore group, because that's what everyone assumes we are, but notice that we're at the extreme end of that chart, with nearly every other single omnivore sleeping more than we do. We fit nicely in the herbivore chart, and I added a prominent dot for us in that one so you can see how we fit in at eight hours a night. If we use a figure of 6-7 hours a night (suggested as natural by longevity research), our placement in the chart becomes even more compelling.

 


Omnivores


Herbivores (least sleep)



Carnivores (most sleep)
 

 

"But what about canine teeth and binocular vision?"

It's part of our collective consciousness that we have "canine teeth" and that this "proves" that we're meat eaters. But the truth is that this argument couldn't be weaker.

Canine teeth are canine in name only. Humans' so-called "canine teeth" are unlike the canine teeth of actual canines, which are really long and really pointed. Our teeth are absolutely not like theirs. In fact, other vegetarian animals (like gorillas and horses) possess the same so-called "canine" teeth.

Overall, our teeth resemble those of plant-eaters much more than meat-eaters. For example, we have molar teeth (plant-eaters do, carnivores don't). Try to find a human-type molar inside your cat's mouth. Our teeth can also move side to side to grind, just like the other plant-eaters, and completely unlike the carnivores. Their jaws go only up and down.

My favorite quote from when someone brought up the canine rationalization on a message board:

"Hey Julia--we evolved with canine teeth? I'd like to see you tackle a steer and tear it apart with those ferocious incisors."

What's funny to me is how the teeth argument is so important to meat proponents when they make their point about canine teeth, and then as soon as they find out that our teeth are much more similar to those of herbivores than of carnivores, and therefore consideration of our teeth suggests that we're designed to be plant eaters -- suddenly what kind of teeth we have is not so important to them after all.

Others have argued that predators have eyes on the front of their heads for binocular vision, while prey animals have eyes on the sides, indicating that we fall into the predator camp. This ignores the fact that the animals that we're most similar to -- the other primates -- have eyes on the front of their heads, and are almost exclusively vegetarian. It's also important to remember what I said at the top of this article: There is certainly evidence on both sides of this debate, but the preponderance of evidence clearly shows that we're suited to eating plants almost exclusively.

 

Does the unhealthfulness of meat mean that it's not natural?
 

The medical evidence is overwhelming: The more animal foods we eat, the more heart disease, cancer, diabetes, and other degenerative disease we suffer. This has been exhaustively demonstrated beyond any doubt. Dean Ornish, M.D. showed that heart disease can be reversed, and he did so by feeding his patients a vegetarian diet. John McDougall, M.D. has also written extensively about how animal foods cause disease, and how he's helped patients regain their health by eating unprocessed vegan foods instead. The esteemed T. Colin Campbell oversaw the most massive study of the relationship between diet and disease, the China Study, which the New York Times caled "the grand prix of epidemiology". His conclusions are the same as the other experts: we're not designed to eat animal foods, because we get sick when we do so. And as mentioned earlier, the Maasai in Kenya, who still eat a diet high in wild hunted meats, have the worst life expectancy in the world. (Fuhrman)

But is this evidence that meat-eating is unnatural?  Maybe so, but maybe not.  On the one hand we expect that's what's natural for us to eat should keep us in the best health (and that would discount meat, at least in the amounts it would take to make us true omnivores).  But on the other hand, people can certainly live well beyond their reproductive years on a mixed animal-plant diet, which is mostly what evolution cares about.  So it's hard to say whether the unhealthfulness of meat is evidence that we're naturally plant-eaters, but then again, we have other, better evidence anyway.  The best evidence that we're supposed to eat primarily plants is the obvious one:  our anatomy.

 

Vegan bodybuilders shatter the myth that vegans are skinny and malnourished.

Human performance on meat-free diets

Not only do vegetarians and vegans easily build muscle, they often excel as athletes too, winning Olympic gold medals and world championships.  In fact, some of the most famous bodybuilders in history were vegetarian. Here's a short list of vegan and vegetarian athletes.

Vegan
 

  • Kenneth G. Williams (bodybuilder) 3rd place at 2004 Natural Olympia
  • Bill Mannetti (powerlifter) 1st place, Connecticut State Powerlifting Championship
  • Robert Cheeke (bodybuilder)
     
  • Joy Bush (powerlifter) 1st place, Connecticut State Powerlifting Championship
  • Jon Hinds (bodybuilder, personal trainer)
  • Charlie Abel (bodybuilder)
  • Mike Mahler (strength coach) ""Becoming a vegan had a profound effect on my training. … [M]y bench press excelled past 315 pounds...and I put on 10 pounds of lean muscle in a few months."

     
  • Mac Danzig (martial arts) MMA record 19-7-1 (as of 4-2010)
  • Tony Gonzalez (Atlanta Falcons tight end)
  • George Laraque (hockey)

     
  • Scott Jurek (ultramarathoner) 7 consecutive wins at Western States 100 Mile Endurance Run, numerous other first place finishes and records
  • Matt Frazier (ultramarathoner), runs NoMeatAthlete.com
     
  • Tim VanOrden (runner) Numerous 1st place finishes
  • Fiona Oakes (runner)  1st place woman and 2nd overall in a 2011 marathon 
     
  • Ruth Heidrich, (triathlete and marathoner) More than 900 first-place trophies and set several performance records. Named One of the 10 Fittest Women in North America.
  • Dave Scott (Ironman triathlete) Six-time Ironman champion
  • Brendan Brazier (Ironman triathlete).  Won the National 50km Ultra Marathon Championships
  • Carl Lewis (track) Numerous gold medals (2 as a vegan)
     
  • Salim Stoudamire (basketball).  Atlanta Hawks
  • Christine Vardaros (cycling)
     

Vegetarian

  • Bill Pearl (bodybuilder) Mr. Universe (3 times), World's Best Built Man, Mr. America, Mr. California, numerous Halls of Fame
  • Roy Hilligenn (bodybuilder) Mr. South Africa (4x), Mr. America, Olympic lifter
  • Ricky Williams (football) Miami Dolphins
  • Prince Fielder (baseball, Milwaukee Brewers)
     

The research on veg vs. non-veg athletes is fairly sparse, but what does exist has failed to show any clear performance benefit for meat-eaters.  (See my separate article, Protein and Strength.)
 


 

 

 

Summary

  • Human anatomy is much more similar to herbivores than carnivores.
  • Humans are omnivores to the extent that we're capable of eating meat (handy from a survival standpoint), but it's not our bodies' first choice.
     
  • Making one contrary point does not magically invalidate all the other evidence as soon as it's made.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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