Did we adapt to cooked food, or is that idea—ahem—half-baked?
In part 1 of this “optimal human diet” series, I mentioned that there is no single, exact diet that will deliver perfect health for everyone. We’re tough cookies, us humans—and we only made it as far as we did by adapting to whatever happened to land on our evolutionary dinner plates. Mastodon meat, sweet little figs, plant roots—we made food of it all.
Even so, there’s a notion in the raw food world that we’re still best-suited for the type of diet we ate back in the good ol’ days. You know, before we exited the tropics, conquered all corners of the planet, and invented the deep-fried Krispy Kreme (which surely triggered the downfall of humanity). Maybe you’ve heard claims that we haven’t adapted to cooked food at all, that we’re designed to be vegan or vegetarian, and that our digestive systems still look like those of other fruit-munchin’, leaf-chompin’ primates.
But do those beliefs hold up to reality? Let’s take a look.
Digestive anatomy
There’s no doubt that we have plenty of anatomical similarities with other primates. We do share a good chunk of their genes, after all—especially chimpanzees, bonobos, and orangutans. In fact, some researchers have argued that chimpanzees should be reclassified under the same Homo genus as humans because we’re so similar, although this is pretty controversial and it’s been challenged by more recent research.
All in all, humans have the same general digestive structure as apes: a single-compartment stomach, a small intestine, a cecum and appendix, and a colon. Pretty simple.
But the devil is in the details, as they say. When you look closer, our digestive tracts have some major differences compared to other primates—differences that pose dietary consequences. The most significant is the size of our small intestine versus our colon. In chimpanzees, gorillas, and orangutans, the colon is about two to three times the size of the small intestine. But in humans, those figures are reversed: the small intestine dominates, clocking in at over twice the size of the colon.
A visual representation for your viewing pleasure (humans are the striped bar):
- Taken from “Nutritional Characteristics of Wild Primate Foods” by Katharine Milton, Journal of Nutrition, 1999
As you can see, there’s not much difference in relative stomach volume—but other primates have a whole lotta’ colon, and we’ve got a whole lotta’ small intestine.
So what does that mean?
In simple terms, a big colon is good for handling “low-quality” foods like tough leaves, stems, and fibrous fruits—things that require a lot of digestive work to break down. Primates that eat boatloads of greens, like gorillas, have a whole army of microbes in their colon that digest cellulose and convert it into an energy source. That’s a process called “hind-gut fermentation.” Humans aren’t so lucky; we can digest some forms of fiber, but much of it passes right through us without delivering nutritional value. Our colons aren’t big enough to host enough little organisms to ferment things as effectively as other primates do.
On the flip side, a big small intestine (is that an oxymoron?) is perfect for digesting high-quality foods that are dense, smaller in volume, and easy to break down. That includes soft fruits, animal foods, cooked foods, tender leaves, and perhaps items that have been pre-processed through chopping or grinding. Even our modern-day blended and juiced foods make our small intestines happy, because that pre-processing translates to less digestive work.
In other words, humans are adapted to a softer, more compact diet than other primates. Our bodies have moved away from extremely high-fiber cuisines and are better suited for foods that require less digestive effort.
What caused the change in colon and intestinal size?
This is one of those mysteries that researchers like to argue about, but no one has a definite answer for. What we do know is that the change was sparked by a shift to more energy-concentrated diets. It could have been:
- A higher reliance on meat, fish, and other energy-dense animal foods
- The advent of cooking and the subsequent “shrinking” of our food size
- Consumption of more nutrient- and calorie-dense plant foods
- The invention of tools for chopping, grinding, and other forms of processing plant matter
More likely than not, it was one (or both) of the first two. Our shrinking colon size is pretty clear evidence that our bodies started adapting to the energy-dense structure of cooked food and meat, since we no longer had to rely primarily on bulky, super-fibrous plant foods.
Does that mean we should all be cooked omnivores?
Even though our bodies have grown accustomed to denser diets than our primate friends, that doesn’t mean cooked food is mandatory or that veganism is impossible. What it does mean is that the most successful human diets are going to have some form of concentrated nutrition. On a completely raw vegan diet, the options are very sweet or fatty fruits, nuts, sprouted grains, coconut, seeds, juices, or blended foods. Although I don’t recommend a lot of gourmet-style raw meals and dehydrated snacks in general, those fit in here as well. On a raw non-vegan diet, those dense items could be animal products like raw dairy, fish, eggs, honey, or raw meat. On a high-raw diet, you could opt for steamed root vegetables, grains, cooked legumes, and so forth.
Basically, what we can’t do is live off of leaves and occasional fibrous fruit for extended periods of time like most primates can. Thanks to our dwarfed colons, we would starve.
Shouldn’t we be vegan because meat causes disease?
I’ve said it before and I’ll say it again: veganism is an ethical choice, not a dietary ideal. Today, we know enough about nutrition to plan or supplement a vegan diet to avoid deficiency, but eschewing all animal products won’t necessarily make you healthier than eating a diet containing a portion of high-quality animal foods.
Part of the reason animal foods get a bad rap these days is because of our farming practices. Agricultural products like dairy, farmed meat, and eggs from grain-fed chickens are a far cry from anything we encountered in the 2 million years prior to agriculture. And the state modern animal products (along with the often-horrific way farm animals are treated) is particularly disconcerting. Along with carrying high levels of growth hormones, pesticide residue, and other harmful substances, grain-fed animal products have a far different nutritional composition than wild animals eating their natural diets. And that spells trouble for the humans who eat such foods.
For instance, grain-fed cattle is significantly lower in omega-3 fatty acids and higher in omega-6 fatty acids than grass-fed cattle—an imbalanced ratio that numerous studies have linked to cardiovascular disease, cancer, and autoimmune diseases.
From G.J. Miller, "Lipids in Wild Ruminant Animals and Steers," published in the Journal of Food Quality, 9:331-343, 1986; image courtesy of EatWild.com
Total fat composition is also much different between commercial, grain-fed meat and wild game:
For more information on the differences between pastured animal products and commercial, grain-fed animal products, visit the Eat Wild site.
It’s certainly no surprise we find high rates of disease linked to these foods. Although animal products and byproducts have been components of our diets for quite a while, “franken-meats” pumped full of hormones and antibiotics are the equivalent of space aliens in our digestive systems. They just don’t belong there. At all.
A word on cooking
Although we have adapted to the energy density of cooked food, we haven’t necessarily adapted to all the new substances cooking produces. Charred meat, for instance, contains compounds called heterocyclic amines (HCAs) known to contribute to cancer in humans. Acrylamide, another human carcinogen, occurs when many starch-based foods are heated. Maillard molecules and glycotoxins crop up in browned foods, and these suckers contribute to inflammation and other unpleasant conditions (research here is still in its infancy). And eating high-temperature cooked food may also accelerate aging due to advanced glycation end products.
In other words, there’s good reason to include plenty of fresh, raw foods in your diet even if you don’t jump on the 100% raw bandwagon. And high-temperature cooking seems to stir up all sorts of trouble, so if you prefer to eat some cooked food, gentle methods like steaming are the safest way to go.
In conclusion…
There might not be a single optimal diet for humans, but health-producing cuisines—especially ones with a reputation for healing ailments and reversing chronic conditions—typically have a few things in common.
- Elimination of refined sugar, high fructose corn syrup, and other nutritionally-devoid sweeteners
- Avoidance of man-made ingredients and fake foods—such as artificial sweeteners, soy-based meat replacements, chemical additives, nitrites, preservatives, artificial flavors, dyes, margarine, and hydrogenated fats
- The inclusion of mineral-rich foods (dark greens, seaweed, animal organs, green juices, or produce grown in well-mineralized soil)
- No pasteurized, homogenized cow dairy
- An emphasis on eating foods in their whole state
- An emphasis on some or all pre-agricultural foods (fruit, vegetables, meat, fish, nuts, seeds) rather than post-agricultural foods (grains, potatoes, dairy, vegetable oils)
- A large portion of fresh, raw foods and/or “living” foods (kombucha, fermented vegetables, kefir)
- High nutrient density
If you eat a diet that fits the above description, raw or otherwise, you’re probably well on your way to staying healthy. Even though I prefer a completely raw diet for the level of clarity and surging energy it brings, I have no reason to think that a 100% raw diet will extend a human’s lifespan or offer more immunity to disease than a mostly raw diet with well-planned cooked foods.
But regardless of what you put in your mouth, remember that an optimal diet is one you can sustain—and that doesn’t knock your whole life off kilter by making you socially, mentally, or emotionally imbalanced. Diet is only one component of health and should never become the driving force in your life.
Yeah i totally agree with you , i was thinking about this the other day and got to similar conclucions ,there are many different health diets that seem to work for different people , raw, paleo, etc.
But there were some common things with all this diets, for example
the use of natural complete foods
the absolute hate and allergic reactions to mcdonalds and highly procesed foods(american diet, or shall i say, global diet)
there is a book you may find interesting, its called “the spartan health regime” i know, the name is utterly ridiculous, and if you read it you will find that sometimes the guy sounds like the lost son of george patton but he has some intereting things, his approach may be considered similar to paleo,(even before paleo diet was widely known) but some of the differences are the extremly high consmption of raw fruit, no matter how sweet, sounds familiar?(yeah baby, mango mango mango)
Anyway, if you are interested in knowing more about it , let me know.
Wow, thanks for the book recommendation! It sounds like something I’ll definitely want to read. Is it available online anywhere, or only in print?
its an ebook, only find it online
bye bye
there is a very interesting subject in raw diet , “energy”.
im an extremly low energy kind of guy , from always i remember not having energy to do stuff and and getting tired very easily , i think its related to health issues , dont know, i even sleep between 9 and 11 hours .
it is possible to improve your health with many different diets, but what seems to be the most seductive part of raw is the massive amount of energy you can get (and having a demigods like glowing skin isnt bad at all jeje)
what can be under discution is the porcentage of raw you need to enjoy this benefits , some of the most hardcore raw foodist say that you only get the best with 100% raw, some say this is overreacting and you only need 80% some others even say that thats bulsh%& and the reality is that with 50%(mostly fruits) you will have all you need
what is your opinion?
i think this would make an interesting post
(by the by denise did you get my email?)
I’ve learned that we tend to have less energy when our insulin levels are high.
To keep our insulin low, it could be helpful to restrict the amount of carbohydrates we eat. While doing that it’s really important make sure to get enough calories to burn as fuel, by increasing the amount of fat we eat.
We also need enough proteins and essential fatty acids as building blocks for the hormones and neurotransmitters like adrenaline and dopamine that make us feel good and energized.
I feel that, for me, eating a high fat, moderate protein, low carbohydrate diet works best to optimize both mental and physical energy.
I do think it’s important to eat something raw regularly.
I start every meal with some raw juicy plants that are low in digestible carbohydrates, like leafy greens, radish or cucumber.
Followed by a complete protein source from the animal kingdom, like wild caught fish or grass fed meat. To make the meal completely satisfying, enough fat or oil is added to meet my calorie requirement.
An example of what I could eat in one day with four meals:
1. Four radishes. Six small eggs with 25 grams of olive oil.
2. Lettuce and dandelion. 250 grams of fish with 50 grams of cultured butter.
3. Cucumber. Four large eggs with 25 grams of olive oil.
4. Endive. 100 grams full fat yogurt with 10 grams shredded coconut and a tablespoon of spirulina. 50 grams of butter.
Preparation:
Egg whites were baked, yolks kept raw and added back after whites were done.
Fish baked so that inside was a bit raw. Sometimes not baked at all but warmed to body temperature.
While I support and practice paleolithic eating and living, I don’t belief in the Darwinian theory of evolution.
While I’m skeptical of the Bible or any religious document, I do belief the different species were created by an intelligence beyond our physical dimensions.
Hi
Great blog
Raw is good for sure. However we have examples of people who ate mostly cooked foods. Native American Indians for example, their diet was based mainly on cooked meat, fat and maize. Saying or suggesting that row foods are healthier than cooked ones is simply wrong.
The key to healthy cooked meats is proper way of cooking. Cooked meat and fat might be much healthier than raw vegetables and fruits. Modern fruits are loaded with sugars. We can say that we are well prepared for ingestion of cooked meats and fats and not so well for ingestion of sweet fruits.
Sweet fruits and colourful vegetables are modern invention. I’m not saying they are unhealthy, I’m saying only they are short in many necessary for human health nutrients.
In long term run I think that high quality cooked meat with cooked fat will be better for most of us than raw vegetables and raw fruits.
There is raw meat diet of course and this is completely different story.
My diet is a mix of raw and cooked meat, raw and cooked eggs and raw and cooked vegetables in small amounts.
I have some chesses and berries time to time, mostly eat butter, goose fat, cream and beef suet.
Probably you know this article, here is the link http://www.manataka.org/page1852.html
Have a good day
Andrew
I think it’s important to note how traditional cultures subsist on dairy, potatoes, and grains with little to no chronic disease. The Masai, for example, have almost no heart disease or cancer, yet get the vast majority of calories from cow blood, milk, and meat.
As long as populations prepare whole grains properly through soaking, fermentation, or sprouting, they tend to do just fine, assuming an otherwise traditional diet. Potatoes are quite nutritious; I think what’s important when it comes to starchy foods is *moderation.*
That said, I do agree with your villifying vegetable oils, heavily processed dairy, and other industrial foods.
Hey Denise,
have you ever heard of the expensive tissue hypothesis? It’s a theory that aims to explain (rather convincingly, I think) the differences in brain size between humans and other primates. Specifically how, due to Kleiber’s law, a bigger brain with its higher energy consumption must come at the cost of a reduction in organ mass elsewhere in the body. In our case that meant a smaller gut which in turn required a more nutrient dense diet (i.e. more meat).
http://www.scribd.com/doc/20045146/The-Expensive-Tissue-Hypothesis
Is kombucha really healthy?
Scientific American did a great article about food, nutrition and evolution a while back that covered the “expensive tissue” issue and a few other things. Here is a link to the article.
http://3dantenna.fileave.com/Scientific_American_Special_Online_Issue-2004-01-11_Diet_And_Health.pdf
http://www.second-opinions.co.uk/carn_herb_comparison.html
I think there is a clue in the fact that the hind-gut fermentation process in the primates and the fermentation in the stomaches of the other vegetarian animals yeild a net energy intake of ~80% fat for the animal. Even thought the animal is eating carbohydrate the bacterial fermentation process turns the carbs into fat, so the animals are burning fat as opposed to glucose as an energy source.
Human digestion does this a little bit, too.
Thank you for this excellent blog.
wholefoods,unprocessed,organic ,fruit and vegetables,sea vegies,nuts and seeds(ground finely so all nutrients possible are absorbed),being well hydrated,herbal teas,fish,eggs and some lean chicken,whole grains,(oats,brown rice,quinoa red and white yes technically a seed~)a good portion of raw food at every meal.THIS is the way of eating,that is allowing my poor little depleted body(from almost 7 years of raw vegan) to heal itself and hopefully fully regenerate.Oh and enjoying some pink himalayan salt,get those minerals in!
Thanks Denise an awesome well thought out article,as always
Nicely done. My one nit is that while we haven’t necessarily adapted to cooking, the opposite isn’t true. I don’t think there’s much actual evidence either way. “Charred meat, for instance, contains compounds called heterocyclic amines (HCAs) known to contribute to cancer in humans” seems like a stretch. Breathing contributes to cancer in humans as well, the question is what is my relative risk from eating charred meat vs. raw?
At any rate, cooking has been around long enough that any significant effect on reproductive fitness should have been seen. That humans continued cooking there food indicates that cooking has somewhere between a negligible effect (positive or negative) to a positive effect large enough to force some selection. And SOMETHING made people keep on cooking (of course something makes people eat bagels and jelly – that doesn’t mean it’s a healthy practice).
Note that this is all in regards to reproductive fitness. If barbecuing your wooly mammoth led to cancer after the reproductive years had passed, then there would be no selection effect.
I’m not looking to get into a debate on raw vs. cooked. I don’t feel like there’s much evidence either way.
Another excellent post, Denise.
Have you read “Good Calories, Bad Calories” by Gary Taubes? Your points regarding the avoidance of dietary toxins are well taken. I think the availability of refined, concentrated carbohydrates may be the single most significant health threat facing modern humans. The current obesity “epidemic” is cleary related to it and not much else, as are the downstream degenerative diseases associated with insulin resistance.
Sounds like you’re a Weston Price fanatic…. Hmmm reccomending Kombucha tea sounds like a good way to tax out the Adrenals. I say that stuff is no good.
Although I’m still not sure about the verdict of raw food and vegan vs. having some Animal protein in the diet, dont follow everything WPF says, they have an agenda too and they are quite vicious about it.