In Defense of Meat Eaters, Part 1: The Evolutionary Angle

Meat is murder.

Meat will clog your arteries.

Meat is an unnatural food.

Man is really an herbivore.

Meat will give you cancer.

Meat is bad for the environment.

It’s easy to forget that these are the common arguments leveled against meat-eaters. It’s easy to forget that most of the developed world assumes meat is inherently unhealthy – for our health, for the environment, and for animals. It’s easy to forget these things because, as Primal Blueprinters, we’re immersed in the literature and are actively involved in what we eat. To that end we understand that man evolved eating meat, that meat is an important part of a healthy human diet, and that meat production doesn’t have to be the unsustainable, industrialized monster it’s mostly become (and which rightly garners the most negative press). Still, what is the average meat eater to say in opposition to these charges?

First, when people condemn meat-eating, they aren’t actually railing against Primal eaters. They’re fighting a bogeyman, a perverted corruption of what a real meat-eater constitutes. They see the slaughterhouse-porn videos and assume that’s how it always goes down. You mention you eat a high-fat, high-animal food diet, and all they see is E. coli-contaminated blood on your hands. You mention something about local farms and pastured animals, but all they hear is the imagined cries of slaughtered calves, fattened on corn and soy that could have fed starving children. You smell the seared gristle and delicious beefy scent of a grilling steak, while they can smell only the excessive methane flatulence of a cow on a junk food diet. Now I don’t mean to paint an unfair or inaccurate portrait of your average anti-meat activist. But the fact remains that many simply have a viscerally negative reaction to the very idea of meat eating. They see the horrible conditions on factory farms and can think of nothing else. It makes sense, actually; I cringe (and wrinkle my nose) whenever I drive by that CAFO in Coalinga on I-5 heading to northern California, for example. If that’s all they see, I can’t say I blame them for being intolerant of meat-eating.

Still, it’s largely an emotional argument against meat eating, and that can be easily countered with real facts and awareness. By definition, an emotive argument shuns reason (when it conflicts) and clings to straws that bolster the emotion. The passionate anti-meat activist even carries a static arsenal of factoids and soundbites that sound true and gel with Conventional Wisdom. They might sound sensible, but they crumble under close scrutiny. My personal favorites are the anti-meat arguments that invoke human evolution as justification, simply because they’re so specious and so easy to counter. Let’s take a look…

Man is really an herbivore.

They love pulling this one. Fruitarians point to the fruit-loving chimps as proof – they’re our closest living relatives (though not as close as the purely carnivorous Neanderthals were, not that they’d acknowledge that little fact) and they eat a diet of roughly 70% fruit, with some insects and other plant matter thrown in. If they’re our closest living relatives, doesn’t it follow that our diet should be pretty similar to theirs? I dunno about you, but I consider six million years of evolutionary change to be a pretty significant amount of time. Oh, and don’t tell them about those chimps that actively hunt monkeys and other apes for fresh, raw meat. Just show them this video instead.

A lot can happen in six million years. Why, it might even be enough time – theoretically, of course – for a hominid to develop a big brain, hands with a precision grip that facilitated tool development, a fully bipedal gait with proper weight transmission at the ankles, mastery over fire, and a fully-fledged linguistic system. But no, six million years isn’t enough time for hominids to adapt to eating meat.

In reality, of course, meat fueled our evolution, as you’ll see in a bit. We are obligate omnivores, if not closet carnivores (if we have to).

But wait – what about our eight times body length small intestine? Carnivores’ small intestines are around three times their body length, while herbivores have much longer ones, right?

Actually, when measured from ass to mouth (the real distance that matters), our 8 to 1 ratio lies roughly in the middle of the pack between obligate carnivores like dogs (3.5 to 1) and cats (3 to 1), and herbivores like cows (20 to 1) and horses (12 to 1). How perfect is that? The obligate omnivore is nestled right in between the carnivore and the herbivore.

Besides, intestinal length isn’t even the best way to determine dietary need. An animal’s particular arsenal of digestive organs is. Actual herbivores have special organs designated for breaking down cellulose – multi-compartmental stomachs, for example. We have but one, and it absolutely cannot break down cellulose to any significant degree. If we were herbivores, we might even have rabbit-like cecums, highly developed digestive sacs that do the brunt of the digestive work for hindgut digesters. I almost wish we had that capability, if only for the advantage of cecotropes – fecal pellets high in vitamins, nutrients, and proteins that rabbits expel for later consumption. Delicious.

Our measly little stomachs can’t handle all that fiber. If a person really wanted to be a true herbivore, he or she’d have to chew cud for hours (that’s why cows are known for chewing cud – it’s a way to predigest all that tough stuff), vomit it up after a little digestive work in the stomach, and repeat the process. Thanks, but I’ll just take some steak with my salad.

And, like clockwork, they interrupt with:

Okay, maybe we did eat some meat, but we were scavengers fighting over scraps. Meat wasn’t a big part of our diet!


Not if you believe the fossil evidence that shows hominids actually manipulated bones “on which flesh was abundant… rather than defleshed from field kills.” We weren’t just starving opportunists. We actively hunted animals, large and small, to obtain large amounts of meat and fat. The only way to get your hands on an intact carcass loaded with delicious flesh – as the evidence clearly shows our ancestors did so on a regular basis – is to kill it yourself. Waiting around for the lions to have their share is hyena territory, scavenger stuff. You don’t become the ultimate predator and propagate your species across the entire globe by solely scavenging for bone scraps – although we did plenty of that, too, as fossil records show evidence of bone marrow extraction from two million years ago using complex stone tools.

If we were meant to eat meat, we’d have claws and big fangs.

Tool-making and large brains are as much an inseparable part of humanity as claws and fangs are of lions. You might argue that claws and fangs “make” the lion, because without them they would die out. Tools and big brains make the man. You can’t take tools away simply because they aren’t a physiological member attached to our bodies; tool making is an integral aspect of human evolution. Our hands and brains make tool usage possible. Think of our tools, our weapons, our hands, and our big brains as our “claws and big fangs.”And as I mentioned earlier, we’ve been using those technological “claws and big fangs” to obtain meat and marrow for at least two million years, plenty of time for tools to become an essential aspect of our human-ness.

Besides, we aren’t arguing that man is purely carnivorous. He certainly can be, but the point of contention is whether meat is a natural part of the human diet. It clearly is. Throwing in shoddy comparisons to actual carnivores like lions and tigers is dishonest and only serves to muddy the waters.

And so, it’s not that we were “meant” to eat meat. It’s simply that we evolved eating meat. Meat represented a reliable source of dense caloric energy packed with nutrients and vitamins essential to our prosperity. Big brains (the existence of which, I’m hoping, even the most ardent vegetarians don’t argue against) were made possible by the consumption of meat, organs, and other nutrient-rich animal products. Instead of spending all their metabolic energy processing cellulose and plant matter, our ancestors turned to a high-meat diet, which utilized fat-soluble vitamins (already converted into the forms we can best take advantage of) and meant energy could be diverted away from a big fermenting pot of a stomach and toward fueling their massive brains. Our brains eat up about 25% of our basal metabolic rate, compared to 8-10% for the apes who eat far less animal matter. Our brains are large and our guts (well, sometimes) are small and bereft of cellulose-consuming bacteria, while a gorilla’s brain is relatively small and its gut enormous and well-equipped with the proper bacteria. How else are they supposed to process all that plant matter?

Easy to digest meat and fat made our big brains possible. I’m not saying vegetarianism makes people stupid, because it doesn’t. I’m just saying they should give credit where credit’s due. You’re able to ruminate on the horrors of meat eating and “articulate” your arguments for a very simple reason: your ancestors ate a ton of fresh, bloody meat and animal fat. Just be glad they didn’t share your dietary proclivities, or else you’d be ruminating on actual grass, twigs, and sticks instead of enjoying culture, language, music, and the other accomplishments of mankind’s big ass brain.

And that about sums up the evolutionary anti-meat angle. It sounds compelling, if all you’ve got under your belt is a semester of high school biology, but it crumbles under real scrutiny.

Tomorrow, we’ll explore a couple other arguments, but for now, let’s discuss any other examples of pseudo-scientific anti-meat talking points grounded in faulty evolutionary science. I’m sure I missed a few…

Read Part II: In Defense of Meat Eaters – Animal and Human Well-Being

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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