TL;DR: Yes. Anthropological evidence points to the fact that human brains rapidly increased in size due to consuming meat, delta-15 nitrogen levels indicate our ancestors were apex level carnivores, and as we switched from a meat-based diet to a grain-based diet roughly 10k years ago our height shrank and we became more susceptible to illness.
This article is part of our 6 part series on the carnivore diet. For previous sections, see the links below:
- An Intro to the Carnivore Diet
- Were Hunter-Gatherers Healthier Than Us?
- Do Plant-Based Foods Have a Dark Side?
- Are Animal Foods More Nutritious Than Plant Foods?
- Is Red Meat Actually Bad For You?
- What to Eat on a Carnivore Diet
Saladino talks about our bodies like cars. He uses the term “user manual” to refer to the right way to operate our bodies and maintain them so they run well. He says that right now, most people are sick. He points out that 87.8% of Western populations have some degree of metabolic dysfunction [61 Ch.11], which he later supports as a main cause of illness in the West behind things like heart disease and other major killers.
[c]
Metabolic dysfunction is a cluster of symptoms and includes at least 3 of the following 5 conditions:
- Abdominal obesity
- High blood pressure
- High blood sugar
- High triglycerides
- Low HDL
It also is associated with developing cardiovascular disease and type II diabetes.
Basically, people are eating the wrong foods, and too much of them and it’s causing many underlying diseases. However, humans were not always in such poor health. Saladino says that the key to finding this user manual to regain our health is to look into our history to see what went wrong, which makes a lot of sense.
We’ll go through a few points demonstrating evidence that we evolved to be carnivores, and how when we started eating grains at the turn of the agricultural revolution, our health took a sharp turn downward.
Meat Made Us Smart
First, Saladino goes through an evolutionary argument for animal foods. His strongest arguments are that brain size rapidly increased when we started using tools and eating more meat, and that our bodies are more similar in design to carnivores than even our closely related herbivore ape cousins.
- Brain Size
One argument he uses is that human brain size rapidly increased right at about the time we started eating meat in large quantities around 2 million years ago. According to Saladino, we have been eating meat in smaller quantities for 5 to 6 million years by scavenging for bone marrow and eating small animals we could catch similarly to apes now.
Here is a timeline of our human evolution:
- Our ape ancestors split off from the other primates around 60 million years ago. Our brain size was about 350 cubic centimeters (cc) at this time
- The oldest fossil we have of this lineage is “Lucy”, of the genus Australopithecus (humans are the genus homo), which is 4.2 million years old. Lucy’s brain size was around 350cc as well, so hadn’t increased much since the apes over about 55 million years of eating an ape like diet mostly of vegetables.
- 2.5 million years ago, the first Homo Habilis species appeared, our ancestor, and cut marks on bones appear signalling the use of tools. Their brain size was about 500cc so had increased quite a lot. Some argue bone marrow had a big role to play in this.
- In the next million years after evidence of hunting, which means we could eat more meat, our brain size doubled to about 1000 cc
- 500 million years ago, we started using fire, long after our brains had already been growing very quickly
Note the rapid increase in brain size starting around 2 million years ago when evidence of tool use began [1]
Saladino notes that some propose that it was starch that truly caused our brains to start rapidly growing. He says that fire is needed to make starchy foods edible, like tubers, and we only started to use fire about 500,000 years ago, well after the big increase in brain size had started happening. Furthermore, when we look at the gene for making the enzyme to break down carbs in our saliva, we have multiple copies of this indicating that we evolved to eat starches. However, when we look at other species that branched off of our ancestors like the Neanderthals and Denisovans (sibling species to humans that died off), which left Africa about 600,000 years ago, they don’t have duplications of this gene. This suggests that only within the last 600,000 years have we really started to eat starches enough to change our DNA to adapt to it. This is far after our brains started to increase rapidly in size.
- Delta 15 Nitrogen
Saladino points to something called delta15 Nitrogen, which is a Nitrogen isotope. This isotope is consistently much higher in carnivores than herbivores.
When human delta15 Nitrogen is measured and compared to other animals, here is where we stack up:
- Herbivores: 3 – 7%
- Carnivores: 6 – 12%
- Neanderthals: 12%
- Modern humans: 13.5%
This shows that on the delta15 Nitrogen scale, humans are higher than even high level carnivores like wolves and hyenas. This indicates we were eating much more animal than plant foods relatively.
- Design of the Human Body
There are a few points here that Saladino brings up. The first uses a comparison of our teeth to carnivores and herbivores. Many people claim that our molars support the argument that we are designed to crush fibrous plant foods like other herbivores, but Saladino points out that our teeth are ridged like a dogs, rather than flat like a sheeps and that our jaws move much more vertically than they do horizontally like other herbivores.
Another strong point he brings up is that the pH of our stomach acid is much closer to carnivores than herbivores, which helps with digesting large amounts of meat. If we compare our stomach acid pH of 1.5 with that of a chimpanzee, a close vegetarian relative, which has a pH of 4 to 5, that is about a 1000x increase in acidity since the pH scale is logarithmic.
A third point he has is that our small intestines are longer than other primates, and our large intestines are a lot smaller. The small intestine is designed to absorb a lot of nutrients without much help from bacteria, and the large intestine contains bacteria (most of the microbiome), which break down plant fibers that we can’t and release short chain fatty acids, which we can then absorb and use. Primates, unlike humans, have very large guts designed for the purpose of getting large amounts of their food from plants this way. Furthermore, when looking at the structure of the chest of humans vs. other primates, we have much less space that protrudes forward designed for our guts.
[d]
A key note is that humans can eat a larger variety of foods than almost any other species, a trait that makes us so well adapted to so many different climates. We are able to eat plant foods and function ok on this diet, which is why we don’t have as small of a digestive tract as other carnivores and we have molars when we need them, but we thrive more on a carnivore diet for many reasons as we’ll discuss below. We also haven’t been carnivores as long as others like the lion or wolf.
[1]
There is a very interesting theory that gut cells and brain cells use the most energy and no animals have a big gut and a big brain at the same time. There seems to always be a tradeoff. Saladino calls it the expensive tissue hypothesis. There are two cell types in our bodies that use a disproportionately large amount of energy: nerve cells including brain cells, and gut cells. In fact, brain cells use about 22x the energy that muscle cells use gram-for-gram, and intestinal cells are similar. It appears that in many animals, there is a trade-off between the size the brain can get and the size the intestines can get due to a limited amount of energy. This seems to align well with the increase in brain size around 2 million years ago as our guts decreased in size compared to other primates.
Saldino finishes off the first chapter by noting just how much of an apex predator we are. We have a “masterpiece” of a shoulder that allows us to throw rocks and spears for hunting, we have the ability to walk upright and see far distances, the ability to run with more endurance than almost any other animal, and we even have evolved whites of our eyes so that other humans could see where we were looking while hunting to improve communication. No other living thing that we know of could hunt and kill anything in sight, pretty much anywhere on the planet. It seems we evolved to become the apex predator in order to reach better and better nutrition. Eating a lot of plant foods diverts energy away from our brain towards digestion, and many on the carnivore diet feel very “clean” burning without a crash in energy after meals.
Recap
To recap, our ancestors split off from the other primates 60 million years ago when we were eating primarily plant foods. Then, around 5-6 million years ago we started eating smaller amounts of meat, and 2.5 million years ago we see cut marks on bones and evidence of hunting more meat. We see our brain size rapidly start to increase around 2.5 million years ago well before the use of fire and the eating of starchy foods. This appears to be in part because we spend less energy digesting meat than plant foods, which gives us more energy to grow our brains. We see a longer small intestine, shorter large intestine, and smaller amount of space for our gut to use bacteria to ferment plant foods. Our jaws have molars that are ridged like other carnivores including dogs rather than flat for grinding like sheep, and our jaws move much more vertically for chopping off flesh than horizontally for grinding plant foods like a cow does. We also see during this period high levels of delta 15 nitrogen indicating that we are high level carnivores.
Next, we enter the period where we start to farm grains for a large amount of our calories starting roughly 12,000 years ago.
Grains Made Us Unhealthy
“The adoption of agriculture, supposedly our most decisive step toward a better life, was in many ways a catastrophe from which we have never recovered.”
— Jared Diamond [1]
12,000 years since the introduction of a lot of grains is not much compared to 5 million years since we introduced meat. Of course, 60 million years on our mostly vegetable based (not grains) diet is even longer, but as we see above our bodies have adapted a lot to a meat based diet over the last 5 million years and especially the last 2.5 million years and we have quite different bodies than other mostly vegetarian primates. It appears that meat allowed our digestive tract to shrink and our brains to grow.
So, what happened when we settled down and started farming grains more than hunting meat?
Saladino goes through a few examples:
- One was a population of hunter-gatherers who switched to farming corn from 950AD to 1200AD in Illinois. During this time, the population increased by 10 times due to more calories being farmed per area and amount of work. However, femur length and tibia diameter in children decreased, and skeletons were much shorter in adults.
- Another example was from Turkey and Greece 12,000 years ago where the average height was 5’ 9” for men, and 5’ 5” for women but when they switched to a grains based diet that shrank to 5’ 3” and 5’ 0” by 5,000 years ago.
- A third is Native Americans at Dickson Mounds who suffered 3 times the bacterial infections in the tibia on their grain based diet vs. their previous diet. In addition, they had an increase in porotic hyperostosis from zinc and iron deficiency, joint and spine arthritic degeneration, and defects in tooth enamel.
When we look at large epidemiological studies in modern times we can see correlations between more animal foods and taller height. The findings in one study of 105 countries were that “In taller nations…consumption of plant proteins markedly decreases at the expense of animal proteins, especially those from dairy”. The Netherlands had the tallest people, and also the highest animal protein consumption. From other sources, there is often a claim that switching from to farming resulted in an average reduction in height of about 6 inches.
Other Books
Saladino references several other works in this section.
In the book Paleopathology of the Origins of Agriculture, 19 out of 21 cultures undergoing agricultural transformation showed negative health shifts in rates of death, physical trauma, degenerative bone conditions and dental health.
Work of anthropologist Jared Diamond, quoted above, notes the lasting negative impacts of a grain based diet after looking at evidence from fossil records. This includes nutrient deficiencies, infectious diseases, hyperostosis in the skull, and smaller and more fragile skeletons.
In the book Nutrition and Physical Degeneration, the dentist Weston A. Price was surprised at how many people he treated had dental cavities and poor teeth formation, but those on traditional diets had perfect teeth and almost zero cavities, even without teeth brushing. He travelled to 14 countries and hundreds of cities over almost 10 years and documented their dental health extensively as well as their diets, and even looked at cases of twins on different diets and what the effects were.
A picture from Nutrition and Physical Degeneration, one sample of teeth examined
He noticed that diet had a much larger impact than just dental health, and that it extended to the formation of the skeleton and health in general. He notes the pristine health of traditional diets like the purely carnivorous Eskimo, and other meat based populations vs. those eating more processed foods. He notes that anywhere that is exposed to processed foods like flours, refined vegetable oils, and sugars very quickly deteriorates in health. He found that processed foods low in nutrients contribute greatly to malformed jaws, jaws that are too small for the teeth, poor immunity, arthritis, and malformed skeletal structures overall. Nutritious animal foods are essential to preventing these problems. He even pioneered the discovery of a vitamin he called cofactor X way back in the 1930s before we knew about it, which we now call Vitamin K.
“It is significant that I have as yet found no group that was building and maintaining good bodies exclusively on plant foods.”
Read more on Dr. Price’s work in our article on why people need braces.
In the book The Fat of the Land, Viljalmur Stefansson travelled to Northern Alaska and lived with the Eskimos over a period of about 10 years on and off in the early nineteen hundreds. During one period, he lived on nothing but meat and water for 5 years and said he felt better than ever. Stefansson notes the Eskimo are some of the happiest people he has ever seen. This book is seen as the number one read in the carnivore communities, at least on Reddit. [5]
Stefansson died at age 82 in 1962 [f]
The medical community didn’t believe him, so he spent one full year in the Bellevue Hospital in New York along with his friend eating only meat and had a team of medical professionals extensively test him on a “regular” diet vs the meat only diet and noted he was in at least as good of health on the meat diet after the full year with no nutritional or health deficiencies.
There are many interesting notes in this book, one of which is that about 800 skulls were analyzed in various museums of people who ate exclusively meat and not a single dental cavity was found, even in those who had no access to dentists and never brushed their teeth, including the Eskimo, certain American Indians, Icelanders, and some prehistoric tribes. In fact, serious anthropologists and ethnologists point to nutrition as being more important than teeth brushing or dentistry in dental health.
In the Eskimo example, their teeth and bones were found to be immaculate. However, as soon as they started trading with Europeans and ate their food, they started to develop cavities. The same happened for Icelanders who had perfect teeth records for about 1000 years before emigrating to Canada and the US at the end of the 19th century. Nutrition and Physical Degeneration above had the same findings. Whenever people start eating high carb grains or processed foods, their teeth start to decay, though high carb potatoes and tubers don’t seem to have as strong of an effect, which is noted in this book in the South Sea Islanders.
But Our Ancestors Died at Like 30!
Many argue that our paleolithic ancestors had a short life expectancy. However, Saladino points out that during the first 15 years of their life, a hunter-gatherer was 75 – 199 times more likely to die than us – due to poor sanitation, infection, wounds, infant mortality etc. Modern medical care allows us to escape these dangers. There often were people in paleolithic times who lived just as long as our elders live now.
When we look at indiginous tribes who eat large amounts of meat like the !Kung, Hadza, Inuit, and Maasai tribes, we see they are on average taller, stronger, and healthier than those in developed nations eating a large amount of grains and even their neighbors with similar genetics eating more grains and less animal foods.
Furthermore, some argue that hunter-gatherers had grueling work lives working more than we do now, however when we look at modern populations of hunters like the Bushmen in Africa, they only spend 12-19 hours per week getting food and can enjoy the rest of their time, the Hadza spend 14 hours a week. We spend about 40 working our jobs.
Indiginous tribes also don’t have the chronic diseases we do including:
- 17% worldwide depression and anxiety rates
- 50 million with dementia in the Western world – and expected to triple by 2050
- High rates of heart disease, diabetes, hypertension, infertility and more
Overall, Saldino has a compelling argument that a meat based diet is likely ideal for an individual person’s health, but when it comes to advancing as a civilization, it seems necessary to have had the agricultural revolution to provide more calories and more stability in location to build structures and populations. It seems doubtful that every person could eat a meat based diet based on land usage. For instance, farming wheat yields 6.5 million calories per acre, corn 12.3, potatoes 17.8, soybeans 2.1 vs. beef at 1.1, pork 3.5, or chicken 1.4 [2]. On average from these examples, plants provide roughly 5 times the calories per area of land used. Importantly though, these plant foods aside from soybeans don’t provide protein and they don’t provide many other nutrients as we will see later on.
