Are humans supposed to eat meat?

Ever heard of the expression “Better than sex”? There are really only two things in this world that expression applies to. One of them is heroin, a well-known highly addictive drug. And the other is food. The importance of food in life, art, and culture cannot be overstated. The earliest cave painting by man dates back about 40,000 years and depicts a hunting scene. The depiction of food in art unquestionably predates the painting of voluptuous reclining nude women, reposing in chaise longues and partially draped in velvet. And did you ever wonder how Ruben’s nude models came to be so voluptuous? Or why the Venus of Willendorf seems to have a BMI in the upper range? The answer is again food. That is why food is connected to affluence and fertility. Just like sex and drugs, food—especially energy rich food—activate our brain’s reward system. Is that not why we often enjoy certain foods even when we’re not really hungry? We use food to train tigers to jump through rings of fire, and food is used to condition distant relatives of wolves to fetch our Sunday morning newspaper. That should tell you something. Countless ex-drug addicts and many generations of pious celibates exist, but the only people I know who do not eat are either dead people or supermodels. Food is what sustained your growth in your mother’s womb. Food is life.

Eating food is something all of us have done since the day we were born. Of course most of us don’t immediately move on to a menu of foie gras d’oei and confit de canard, accompanied by some fine bottle of châteaux clos vougeot for example. Instead, most humans begin life by eating what their parents feed them. Home cooked food, mostly. Some recipes acquired during the lifetime of the parents, others passed down through generations. Recipes for boiling vegetables, recipes for making salads, recipes for stir-frying noodles, and recipes for preparing meat. Everything and anything. There isn’t much that walks or crawls on this earth that isn’t eaten in one culture or another. Humans are really typical omnivores, a lot like baboons or chimpanzees. You’d be hard pressed to find a culinary culture on this planet that does not include nuts, fruits, vegetables, roots, and some form of animal protein. So imagine my surprise when I encountered a page on the PETA website boldly asserting that humans are not supposed to eat meat.

Of course I understand that PETA is an organisation that promotes animal rights and welfare, and that slaughtering animals is not a practice that agrees with those principles. But unorthodox claims such as theirs must be supported by plain facts. Anything less basically implies the use of  dezinformatsia to promote some kind of agenda. So how do their biological and evolutionary arguments stand to critical analysis? Recently I have tried to find that out.

Their first argument against eating meat is that most humans can’t stand the sight of blood, intestines, and raw meat. This, in my humble opinion, reflects a cultural bias. Because most humans do not live in highly developed Western countries, where the consumer of meat is shielded from the modern industrialised slaughtering and butchering process. Indeed, there are plenty of cultures on earth that still hunt for food, eat raw meat, and some even drink blood. Check out this video of the Massai drinking blood and eating raw meat, and note how none of them vomit, pass out, or seem otherwise disgusted by their meal.


If people from Western cultures can’t stand the sight of a slaughtered animal, then it is probably because they never see an animal butchered anymore. In the book Ozma of Oz (1907), the protagonist Dorothy Gale stumbles upon a lunch-box tree that grows containers with ham sandwiches. You may perhaps laugh at the idea—and admire the creative genius and humor of the author—but in Western society this way of thinking about where meat products come from is actually not far from the truth anymore. However, let me assure you that for most people on earth the sight of a slaughtered animal signals the potential for a tasty dinner.
The next point PETA makes is that humans don’t have carnivorous teeth or claws, and therefore are not built to kill and tear apart animals. Nonsense I say. I would argue that humans have the biggest, sharpest canines in the whole animal kingdom. I have included a picture below to demonstrate the typical size and nature of a specimen that would put even the greatest predators to shame. 
My, what big teeth we have!

A fairly typical example of the kind of tooth humans use to tear into flesh, though much bigger specimens exist. For comparison; a Bengal tiger’s canines are only about 10cm in length.


Clearly, our species is perfectly capable of dealing with cadavers. Humans have used tools and cooked their food at least since the stone age—which began about 2.6 million years ago—and evidence of the first spears dates to at least half a million years ago. And there is also plenty of scientific literature showing that our proclivity for the omnivorous lifestyle is very much a part of our evolutionary heritage, as this Nature article highlights for example. It remains an open question to what extent meat was part of the early hominid diet, and it is beyond question that excess consumption of animal products in the Western diet is a an important contributing factor to what have come to be known as ‘lifestyle-diseases’. Yet that is far more a problem of recent industrialisation and the ensuing cornucopia of meat in our modern world, than a biological problem with eating meat per se.

But then PETA continues with the argument that “Our digestive system doesn’t like meat”. Here they again demonstrate that they don’t quite understand biology that well. Yes the gastro-intestinal (GI) tract of humans is not as short as that of carnivores, but neither is it as long as that of herbivores. And there exists at least one scientific publication noting that humans have low gastric acid pH values that are on par with those of predators and scavengers. Another paper compared the acid levels between the beagle (a domesticated carnivore) and humans, finding that human gastric juices are actually more acidic. Yet another paper compares a particular property of the GI tract—the coefficient of gut differentiation—for a number of species ranging from predators and scavengers to herbivores and omnivores. In that study, humans are ranked among the omnivores. Thus the omnivorous diet of humans is not just a lifestyle choice, it is clearly a biological fact.
The PETA page goes on with the statement that meat may cause food poisoning in humans. To that I would say “And vegetables don’t?” People can become violently ill from peanut allergies, deaths from eating unripe tomatoes still occur in a few cases each year, and some individuals risk their lives by mistakenly eating poisonous mushrooms or a rotten potato salad. Except for maybe a few edible fruits—which the plant offers only because it benefits the plant’s reproduction—nothing in nature wants to be eaten, and almost every organism will basically try as hard as possible to kill you if you give them half a chance. That is why completely immunocompromised people don’t live long; they die of infections that no normal human would ever have to worry about. Plants, unlike animals, can’t run away, so they stand their ground and synthesise powerful toxins to avoid herbivory. Eating badly prepared, poorly selected, or rotten fruits, vegetables or mistaking a toadstool for a safe mushroom can make you just as sick as eating bad meat. In 2017, a then 74 year old Dutchman nearly died after eating some apricot seeds that he’d bought at a health food store. So just because something isn’t an animal doesn’t mean its safe to ingest. Eating correctly prepared meat, on the other hand, is pretty much just as safe as eating anything else that doesn’t contain toxins and food-borne pathogens in quantities that could cause illness. 

And PETA also asks the question “If humans were meant to eat meat, why do meat-eaters have a 32 percent higher risk of developing heart disease than vegetarians?” Well, that is perhaps because people who eat meat are often consummate bon vivants who al to frequently overindulge, overwhelmed as they are by sudden bouts of joie de vivre. Also, such studies look at processed meat. In other words, many meat eaters dine too often on modified cuts with too much additives. It’s that inconvenient reward system of the human brain again, overruling reason. And no one ever said living the good life would be a long life. And if just eating veggies is so awesome, then why don’t we naturally gravitate towards a plant-only diet? Why don’t children eat only the boiled vegetables, while leaving the fried chips and grilled meat untouched? How many parents have arguments with their children because they only eat cabbages and carrots, but avoid hotdogs, pepperoni pizzas, and barbecued meats? I vividly remember how my mother would not put her mouthwatering pancakes with bacon and thick syrup on the table until I first ate my spinach. And when I was about five or six years old, I came downstairs to the kitchen one early morning, used a chair to climb on the counter, and started eating brown sugar straight from a jar. Why didn’t I go for the bowl with tomatoes? Examples from my own life are just anecdotal evidence of course, but a quick glance at the literature shows that most humans are born with a preference for energy dense food. That is why it may take some time before a child ‘learns’ to eat Brussel sprouts, whereas sweet confectionaries and junk-food are instantly appreciated by all. And once a society becomes sufficiently wealthy that anyone can afford to eat steak every day of the week, then some people will actually do just that.

An increasing amount of research is finding that the differences are not just related to differences in experience with foods, but that there is also a genetic component involved in taste. There are innate differences in sensitivity to bitter taste, for example. And there may be an epigenetic component as well. For example, a recent study found altered DNA methylation patterns in Dutch people who were prenatal when their mothers lived through the Hunger Winter during the second world war. That particular cohort experienced a number of associated health problems later in life, including obesity and metabolic diseases. Thus, while I would certainly agree that humanity ought to eat less meat, we should also appreciate that there are inborn biological factors that determine our eating habits, our gustatory senses, and our metabolic constitution. But there are ways to encourage a healthier balance in our diets. The UK has famously imposed a sugar tax in an effort to stem the tide of obesity that threatens to put an increasingly huge burden on their healthcare system. It would be just as easy to tax meat for the same reason, and other reasons as well (animal husbandry also contributes to climate change, for example).

So should humans eat meat? Well, my problem is with the word ‘should’. From an environmental perspective, assuming a certain set of strict moral and ethical standards regarding animal life, the answer is no. But from a biological perspective the answer is yes. Yes, we ‘should’ eat meat, but we should do so in moderation just like every treat in life. Not more than once or twice per week. Because while eating meat is a part of our evolutionary history, the amount of meat we have only recently begun to consume every year certainly is not. As with all things in life, neither excess nor shortage are good.

Having answered the original question, I would like to end with a note on some of the references I often see in the kind of pro-vegan writings I have found online. Beware of statements that begin with “a professor from Harvard” or “a distinguished surgeon in Kansas”. When a sentence begins with throwing around academic titles and fancy research institutions, I have found that what follows is typically either some misinterpreted fact or a plainly incorrect one. You want an example? Alright. The PETA page that prompted me to write this post at some point refers to an article on Huffpost: “Shattering The Meat Myth: Humans Are Natural Vegetarians“. The author of that piece—Kathy Freston—cites an essay written by a Dr. Milton Mills, titled “A comparative anatomy of eating”. And what do you see when you read that essay? No references of any kind, and an absolutely shameful load of twaddle on human evolution and physiology. And that from an alumnus of the medical school of Stanford (apparently). Go figure…