Meat has gotten a bad rep. If you are to believe the headlines, it’s to blame for everything from heart disease to stomach ulcers to global warming. Given that meat, and red meat in particular, has received so much bad press over the past several years – especially following the World Health Organization’s (WHO) release of the report saying that the consumption of processed meat is carcinogenic and the consumption of red meat is probably carcinogenic – it’s not surprising that vegan and vegetarian diets have become more popular as of late.
Part of the reason why meat has gotten a bad rep is that it typically contains quite a bit of fat; a macronutrient that many nutritional authorities have long been at war with, in the sense that they’ve been fighting to push it out of our diets and insert carbohydrates in its place. Not everyone shares this sentiment though. Recently, the low-fat army has faced increasing resistance in the form of advocates of Atkins-type diets who claim that we should embrace, as opposed to shun, fatty foods. Given that there is so much conflict in this arena, it’s not surprising that the public is confused about what it’s healthy to eat.
An evolutionary perspective can help us bring order out of this chaos and determine what type of diet that suits our biology…
Does meat deserve its bad rep?
As I see it, there’s no doubt that many of the meat products that line the shelves of modern supermarkets contribute to fueling the development of diseases of civilization such as colon cancer and heart disease. Processed meats such as sausages, salami, and corned beef are particularly problematic in this regard, seeing as they have an unnatural fatty acid profile and typically contain a lot of salt, nitrates, and/or other preservatives.
This is widely recognized. I don’t think any reasonable nutritionist or dietitian will disagree that it’s unhealthy to consume a lot of those types of foods. But what about unprocessed meat? Is that something we should avoid as well? If you ask a vegan that question, the answer you’ll get will with a high degree of certainty be yes. If you ask an evolutionary scientist, however, chances are you’ll get a very different reply.
He will likely tell you that animal source foods have been an important part of the human diet for millions of years and that there’s no reason to think that we’re suddenly not adapted to consume meat. If he’s a knowledgeable and bright man, he’ll probably add in a caveat though, which is that modern supermarket meat differs in several respects from the game meat that contributed to fueling the evolution of our kind. Perhaps most importantly, it has a very different fatty acid profile…
The fatty acid composition of an animal’s tissues is greatly affected by the animal’s diet, activity pattern, and health
If you rarely exercise and eat a western-type diet, rich in saturated fats, salt, and sugar, a different fatty acid structure will generate in your tissues than if you are very physically active and eat a hunter-gatherer type diet, rich in fiber and omega-3 fatty acids, while low in processed foods. This is not only true for your adipose tissue; it also applies to other lipid-containing parts of your body, such as your brain (1, 2, 3, 4). Obviously, the former way of life will also cause you to accumulate more total fat than the latter.
Sheep, cows, deer, and other animals are no different from us humans in this regard, in the sense that the fatty acid profile of their tissues are also affected by nutritional factors. Meat that’s derived from a cow that was raised in a feedlot on a grain-heavy diet will have a very different fatty acid profile than meat sourced from an antelope that lived in the wild on the African savanna (5, 6). This seems obvious, but it’s often overlooked nonetheless, which is concerning, seeing as it has major implications for nutrition and medicine.
Animal source foods were our ancient ancestors’ no.1 source of fat, a class of nutrients that greatly contributed to fueling the evolution of the complex human brain and body (7, 8, 9); hence, it goes without saying that the sudden and major change in the fatty acid composition of the meats that we humans eat has had major implications for how our bodies function. This change was initiated by the Agricultural Revolution and gathered speed quite recently, when it became normal to mass-produce meat in large feedlots.
Here’s what the authors of the book Principles of Evolutionary Medicine had to say about this matter:
Through time, human herding cultures have selectively bred the animals that produce the fattest, tastiest meat. This has maximized the qualities that improve flavor, such as marbling, which involves the deposition of fat droplets (triglycerides) within and between the muscle cells. In addition, industrial herding practices in places like the USA often involve feeding animals grains, such as cord, which is grown in abundance with generous federal subsidies, rather than the grasses that are their natural food resource. (10)
The balance of fatty acids found in game meat supports optimal functioning of the human brain and body
Game meat is superior to meat from domesticated animals fed an unnatural diet (e.g., a grain-heavy diet) in that it contains much less saturated fat and total fat and more Polyunsaturated Fatty Acids (PUFAs), mostly in the form of long-chain omega-3 fats (5, 6). It also contains less monounsaturated fat. Basically, it has a completely different fatty acid profile. Meat from pasture-fed animals is much better than meat derived from animals fed a species-inappropriate diet, but it’s not as great as wild game meat. Perhaps most importantly, it doesn’t contain as much healthful PUFAs (5). The fact that the fatty acid profile of game meat differs markedly from that of industrially produced meat helps explain why meat consumption has recently been implicated in the pathogenesis of some diseases.
It’s well-established that one of the key reasons why the human brain started growing rapidly some 2-3 million years ago is that our ancestors incorporated more animal source foods, rich in brain-selective nutrients such as PUFAs, into their diets (7, 8, 9, 10, 11). PUFAs, in particular omega-3 PUFAs, are integral to the functioning and maintenance of the human brain (7, 8, 9, 10, 11). By depleting our diets of these lipids, we’ve changed the way our brains grow and function. Our brains are starving for real food. They don’t do so well on a processed, modern diet.
The idea that it’s unhealthy to consume meat has not evolutionary support. Meat has been an important part of the human diet for millions of years (8, 9, 10). Hunter-gatherers don’t get colon cancer or heart disease, despite the fact that they tend to eat quite a bit of meat (11, 12). In other words, it’s not the meat per se that is the problem, but rather the way we produce meat these days. Modern meat has an abnormal nutrient composition. It’s also worth noting that certain modern food preparation and processing techniques are problematic, from a health perspective.
Basically, by changing the way we produce, procure, and prepare our food, we’ve significantly altered the co-evolutionary relationship that exists between ourselves and the animals we derive our food from. Natural selection has never gotten around to reconfiguring the human body so that it thrives in this changed relationship.
Meat has been an important part of the human diet for millions of years. There’s no reason to think that meat suddenly no longer agrees with the human biology. Meat isn’t the problem per se; rather, the problem is that modern, industrially-produced meat differs markedly from game meat. Perhaps most importantly, it contains a lot more total fat and saturated fat and much less omega-3 fatty acids. This helps explain why the consumption of meat has been shown to play a role in the development of some human diseases.
We evolved eating fairly lean game meat rich in PUFAs, as well as fatty tissues such as bone marrow (derived from wild animals). We did not evolve eating meat from fat, sick animals raised under crowded, unsanitary conditions. Obviously, today, most of us aren’t able to consume exclusively wild meat; however, we can make a conscious decision to get as much of the animal products we buy as possible from companies and farmers that favor quality over quantity and give their animals the space and nutrients they need to be healthy.