Wednesday, March 4, 2009

What Can Evolution Teach us About the Human Diet?

Vegetarians deserve our respect. They're usually thoughtful, conscientious people who make sacrifices for environmental and ethical reasons. I was vegetarian for a while myself, and I have no regrets about it.

Vegetarianism and especially veganism can get pretty ideological sometimes. People who have strong beliefs like to think that their belief system is best for all aspects of their lives and the world, not just some aspects of it. Many vegetarians believe their way of eating is healthier than omnivory. One of the classic arguments for vegetarianism goes something like this: our closest living relatives, chimpanzees and bonobos, are mostly vegetarian, therefore that's the diet to which we're adapted as well. Here's the problem with that argument:

Where are chimps (Pan troglodytes) on this chart? They aren't on it, for two related reasons: they aren't in the genus Homo, and they diverged from us 5-7 million years ago. Homo erectus diverged from our lineage about 1.5 million years ago. I don't know if you've ever seen a Homo erectus skull, but 1.5 million years is clearly enough time to do some evolving. Homo erectus  ate animals as a significant portion of its diet.

If you look at the chart above, Homo rhodesiensis (often considered a variant of Homo heidelbergensis) is our closest ancestor, and our point of divergence with neanderthals (Homo neanderthalensis). Some archaeologists believe H. heidelbergensis was the same species as modern Homo sapiens. I haven't been able to find any direct evidence of the diet of H. heidelbergensis from bone isotope ratios, but the indirect evidence indicates that they were capable hunters who probably got a substantial proportion of their calories from meat. In Europe, they hunted now-extinct megafauna such as wooly rhinos. These things make modern cows look like chicken nuggets.

H. heidelbergensis was a skilled hunter and very athletic. They were top predators in their ecosystems, judged by the fact that they took their time with carcasses, butchering them thoroughly and extracting marrow from bones. No predator or scavenger was capable of driving them away from a kill.

Our closest recent relative was Homo neanderthalensis, the neanderthal. They died out around 30,000 years ago. There have been several good studies on the isotope ratios of neanderthal bones, all indicating that neanderthals obtained most of their protein from meat. They relied both on land and marine animals, depending on what was available. Needless to say, neanderthals are much more closely related to humans than chimpanzees, having diverged from us less than 500,000 years ago. That's less than one-tenth the time between humans and chimpanzees.

I don't think this means humans are built to be carnivores, particularly since there is accumulating evidence of diverse plant consumption by neanderthals, but it certainly blows away the argument that we're built to be vegetarians. Historical human hunter-gatherers had very diverse diets, but on average were meat-heavy omnivores. 

31 comments:

Robert M. said...

BBC video of chimps hunting monkeys:

YouTube video

I think it's pretty clear, once we gained the capacity to fabricate tools, our ancestors were able to crack open the skulls and bones of our prey for brain and marrow. This would have been an excellent source of the polyunsaturates required for bigger brains.

The other big evolutionary shift in the human chain is bipedal locomotion. It's more efficient walking over long distances but has a much slower top-speed than any quadruped, so pack hunting and social groups would have had to developed first, both for hunting and protection.

chlOe said...

Also mother's milk even mimics animal-fat with AA acid, even if it's in small amounts.

"It should be considered, however, that fat in human milk contains, mainly in the phospholipid fraction, some arachidonic acid--the long-chain polyunsaturated derivative formed through de-saturation and elongation of the short-chain precursor in animal tissues--which is more actively incorporated than the short-chain precursor in growing tissues, especially brain."
--"PRE- AND POST-NATAL DEVELOPMENT", C Galli and A. Socini; "Dietary Fats and Health", 1980's


Great points about monkeys and people.
You should also mention that chimps and gorillas have to get their B12 from either bugs or feces; so anyone who is a vegan might not want to commit so much - hence, B12 supplements. Totally natural of them.
I loved the image; 5 million years is a prettttaay long time.

Eric Daniels said...

Stephan,

Love the blog and have enjoyed it for a while now.

One question on this post. You wrote that chimps aren't hominids. Is that right? I thought chimps, humans, gorillas, and orangutans were all from family hominidae. I know genus Pan and genus Homo diverged (according to standard theory) about ~5 million years ago, but they both came from the Homonini tribe didn't they?

This does not, of course, change your fundamental point that using chimps' modern diet to argue about ours is silly since ~5 million years of separate evolution of ancestry would be plenty to change our characteristics.

Just curious why you say "chimps aren't even hominids." I know there is some controversy here, so I wondered what your reasoning was.

chlOe said...

Eric, the oldest hominid should be whatever diverged from the ape I'm pretty sure. So Apes and Hominids are probably separate categories. I think you're thinking of Primates, in which, we do belong as well as things like aye-ayes, monkeys and apes do.

Stephan said...

Eric,

I believe you're right, thanks for the correction.

AngloAmerikan said...

I believe there are also important differences in the digestive tracts of chimps nad humans. It looks like humans are built for digesting more energy dense food. Today we have digestive tracts that are are not well designed for the super-energy dense food we consume so further modifications are necessary. Evolution will probably eventually sort this out however humans have discovered they can do this themselves with gastric bypass and similar surgery.

Perhaps all humans should have their stomachs stapled soon after birth.

chlOe said...

Well damn, I guess apes are hominids
http://en.wikipedia.org/wiki/Hominid

my bad
It's been a while since biology..hm.

Drs. Cynthia and David said...

Great post Stephan. I am reminded of a health channel show I saw where a misguided dietician had a group of people eat the same diet fed to the gorillas in the zoo - basically a lot of raw vegies and fruits (presumably without the insects and feces, where the B12 was supposed to come from is anyone's guess- on the other hand you can live for a good while without supplements of B12, so the bad consequences of such a diet don't show up for a while). The people were constantly running to the bathroom as their intestines tried to purge the excessive fiber. I also remember once seeing how the mother gorilla teaches her young to eat their own feces- now we know why.

Geart video too Robert. It's much more difficult to video chimps hunting than sitting around eating fruit and grooming each other. They had to at least ask the question- do chimps hunt? - in order to find out. Just like with any scientific endeavor- you have to ask the right questions first, otherwise you observe only what you expect to see.

Cynthia

Aaron Blaisdell said...

My bachelors was in paleoantrhopology so let me teach some nomenclature. The apes are in the taxinomic group (I think at the family level) Hominoidea, and thus can be called hominoids. Humans and our non-ape ancestors are in the taxinomic group (I think it is the subfamily level) Hominidea and thus can be called hominids. Thus, chimps are hominoids but not hominids. Humans (and australopithicenes, and paranthrapus, etc.) are hominoids and hominids (they're different taxanomic levles).

Aaron Blaisdell said...

And please forgive all of my spelling errors. I've been flying all day (LA to Pittsburgh), and never was any good at spelling!

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Stephan said...

AngloAmerikan,

I think we are designed to digest the most energy-dense, fiber-poor food around: fatty meat. That doesn't mean we can't tolerate foods of lower energy density and higher fiber, but in my opinion it supports the theory that the energy density of the modern diet isn't the problem.

Cynthia,

Ha ha. I can imagine the scene: "OK son, you can be vegan if you want but you're going to have to learn to eat your own poop..."

Aaron,

Thanks. This stuff is outside my field so I'll rely on you to correct my errors!

Drs. Cynthia and David said...

You have to read this article about an archeological find in Turkey- the Garden of Eden! It's a thought provoking story.

http://www.dailymail.co.uk/sciencetech/article-1157784/Do-mysterious-stones-mark-site-Garden-Eden.html

Cynthia

toddhargrove said...

Interesting article on the "Garden of Eden." Daniel Quinn would have something to say about this. He has long hypothesized that the legend of the fall is a fable told from the perspective of pastoralists such as the Semites who were living along side of some who started what Quinn calls "totalitarian agriculture."

Stephan said...

Cynthia,

I saw that article, it's amazing.

Ryan Koch said...

Good stuff, Stephan! I'll be sure to follow your blog from now on.

I couldn't agree more with your stance on the hominid diet. Well put and well articulated. One thing I would like to mention is the amazing fact that these ancient near-carnivore humans also maintained good physical health, as evidenced by their perfect teeth and beautiful noggins -- modern civilized humans don't compare!

Stephan said...

Ryan,

I agree. I think you might enjoy these three posts that discuss cranial development and nutrition:

http://wholehealthsource.blogspot.com/2009/01/vitamin-k2-and-cranial-development.html

http://wholehealthsource.blogspot.com/2009/02/cranial-development-in-nepal-etc.html

http://wholehealthsource.blogspot.com/2008/08/life-expectancy-and-growth-of.html

I looked at your blog, it's interesting. Take a look around my archive sometime, I think you'll find a lot here you resonate with.

Shelley said...

Do you have any advice for someone eating a mostly raw food diet?

I have investigated the paleo diet however, I have difficulty eating meat & fish due to moral reasons, so this really cannot work for me.

Is a raw food vegan diet (not consuming grains) the next best choice to the paleo diet?

Stephan said...

Hi Shelley,

I would recommend a vegetarian diet over a vegan diet for health. You can still eat raw dairy and eggs if you want to. Egg whites should probably be cooked but I think raw yolks are fine. My opinion is that a long-term vegan diet is bad news for health, even if it's raw.

Vin said...

Another great article supporting our need to remember what we came from!

Are you familiar with Metabolic Typing? As you suggested, traditional diets varied greatly, mostly as a result of what was geographically available. Although I completely agree that we're not all meant to be vegetarians, not everyone does well on a high protein and fat diet (I certainly do though!). Metabolic Typing is a great tool that assists in figuring out the individual needs of each person.

Stephan said...

Vin,

I haven't made up my mind on metabolic typing yet. I think a healthy person can probably do fine on just about any historically-validated macronutrient ratio as long as food quality is high, but I'm open to the idea that each person has an optimum balance. I know I feel best when I'm getting roughly 40-60% fat, 15-20% protein and 20-45% carbohydrate. That's quite a range though.

Alexander said...

It's easy to get vitamin b12 and the fat soluble vitamins if you are vegetarian.

I have not eaten meat of any kind for 8 years and am extremely healthy.

Most of the meat available today is extremely unhealthy; it does more harm than good.

You can be healthy as a vegetarian and a meat eater.
Likewise, you can be extremely unhealthy as a vegetarian or meat eater.

It just depends on the quality and variety of the choices you make.

Also, those who lived hundreds and thousands of years ago ate what was available.
They didn't have the luxury of choice that we do in our modern world.

Dana Seilhan said...

Re: the killing off of the megafauna: that is only a hypothesis, not a done deal. There is a lot of good argument *against* the idea, actually. The climate was changing at about the same time early humans were going after mammoth and such, and the numbers of humans versus the numbers of megafauna argue against it as well--as one writer put it, and I wish I remembered his name, if early indigenous Americans had killed off all the mammoth and other megafauna in the Western Hemisphere, they'd have been "so fat they would have to have waddled to Tierra del Fuego." I don't know if I agree with that literally, but it certainly makes no sense that they would have wasted that much food, and if you're on a mostly meat-based diet, you don't actually need to eat as much in the first place.

Re: the necessary vitamins, as the previous commenter stated: Unless you are an ovo-lacto vegetarian, you cannot get vitamin A nor the more useful form of vitamin B12 from a vegetarian diet, specifically a vegan one, unless you rely on supplements. And at that point you're talking something of animal origin for the vitamin A because no plant food contains it. Human beings are poor converters of beta carotene at the best of times; if you're very young, very old, or have a chronic disease, your conversion rate is near to zero. I found out the hard way that if I rely on beta carotene for my vitamin A needs, I won't get enough vitamin A and it causes me reproductive health problems.

As for B12, vegans must obtain it from supplements, and I question how sustainable it is to obtain one's nutrition from a factory. Not that veganism is sustainable anyway. No form of diet that depends heavily on farming is sustainable. It devastates forests, destroys the topsoil and leaves human beings vulnerable to famine because they must live sedentary lives rather than move to where the hunting is good.

I've heard the "thrifty gene" types claim that we get fat because foragers (hunter-gatherers or gatherer-hunters or whatever silly phrase is used for them now) had to be able to cope with famine, but you don't get true famine being a forager, because you can follow the food. That's not true of wheat, corn, or soy. Anyway, if the "thrifty gene" hypothesis had any validity to it, the obesity rate in Europe should be at least five times as bad as our own. They had far more famine than Native Americans did, and live closer to their ancestral diets now than Native Americans do.

In any case, I do think we're carnivores. But we're non-obligate carnivores, as dogs are; we can eat other foods without suffering malnutrition immediately. Contrast this with obligate carnivores such as cats, who must have meat or they go blind and die. But that doesn't mean it's good for us to go without animal foods permanently.

Dana Seilhan said...

And, let me add that just because the other great apes eat partially vegetarian or all-vegetarian diets doesn't mean they are naturally evolved to eat that way. It's worth pointing out that they share a lot of our characteristics even though we are far diverged from them, and one of those characteristics is a reliance on culture to partially replace instinct. Including cultural mores about what to eat.

Gorillas are held by human beings to be vegetarians but you can feed them meat in a zoo environment and they will eat it and thrive.

Chimps hunt monkeys, as other commenters have pointed out here.

Orangs eat fruit, but orangs also have a lot of abdominal fat. And I read recently (again, I wish I had the link) that a group of orangs that had been released from captivity into the wild weren't real sure how to live like other orangs, so they sort of made it up as they went along. It's not hard to conclude that some of them decided at some point that it was easier to pick fruit than it was to hunt monkeys. They're not very active critters most of the time.

I've seen vegetarians declare their diet superior because they're "better" than animals. So there's a bit of self-delusion going on there, a bit of separation from the natural world--ironic when you consider the claim that they adopt the diet to be more natural.

Smart said...

Of course we're omnivores. Only people ignorant of nutrition claim that we're natural herbivores or carnivores. Getting a reliable B12 is already a problem (unless if you eat miso). It's natural for primates to have their diet predominant with plants. But showing at the nutrition of ice age people, doesn't really show that we're good omnivores. Ice age people simply ate whatever they had, meat and pine nuts. In our natural habitat, warm South Asia and Africa, our natural diet has many plants. Bushmen eat fruits, nuts, berries and tubers. We should look at them about what is natural to eat and how our bodies function, rather than looking at what ice age people ate. That's not good to disprove any theory. Put an animal in a habitat with all food sources, plants, meat, fungi, seafood, and then do conclusions. Then do some science. Can we biosynthesize vitamin C or B12? No, so eat both, plants and animals. But I still eat a japanese diet of little fish. Too much meat causes osteoporosis, arthritis and cancer.

hopeful geranium said...

No it doesn't. You won't find any scientific proof of that. Masai and Inuit, the two peoples that eat the most meat, have strong bones, no cancer, no rheumatoid arthritis. All three, as disabling or killing diseases, are modern carbohydrate diseases not seen in hunter-gatherer societies. You might get some osteo-arthritis, which is due to fair wear-and-tear. But not nearly as much as you see in modern peoples who move less - including the Japanese.
Modern US meat is grain-fed so not as healthy as, say, NZ meat which is still pasture-fed. Bushmen used to, still may, kill elephants for food; that's a lot of red meat and saturated fat.

soohum said...

Hi there!

I realize this is a pretty old string. But I see a lot of misinformation here about vegetarianism. If you eat meat, that's your choice, but look at the science first, and please don't continue to be misinformed about the numerous vegan (and lactovegetarian) sources of B12.

Physiology of a carnivore:
*Short intestine, about the length of the body and highly acidic gastric fluids optimized for getting meat through quickly so it doesn't putrefy in the gut, as well as easy digestion of cholesterol and saturated fats prevalent in animal food. No need for fiber to help things along because intestine is short.
*Sharp teeth for tearing flesh
*Claws (as opposed to nails)
*Lap or lick water (as opposed to sipping)
*Perspire through tongue (not skin)
*Great night vision suitable for hunting

Physiology of an Herbivore:
*Flat incisors and molars for grinding grain
*Long intestine suitable for absorbing nutrients deep within grains (meat will putrefy in the gut of a natural herbivore), not as acidic gastric fluids, little to no ability to break down saturated fats and cholesterol without extra fiber.
*Fingernails (vs claws)
*Sip water (vs lapping or licking)
*Perspire through skin (not tongue)
*Night vision is poor.

Does it take a rocket scientist (or biologist) to figure out which category you (and humans in general) belong in?

And now the Vegan sources of B12. It is a terribly common misconception that B12 only comes from flesh. In fact, B12 is a product of fermentation and has little to do with the medium it is grown in. Here they are:
*Idli and Dosa (google them, they're fermented south Indian foods)
*Chlorella tablets or powder (a green algae, great for you anyway)
*Miso
*Nutritional Yeast
*Leave a glass of cooked rice out in water overnight on the counter. Drink the water portion in the morning. This simple, easy fermentation creates the whole B complex.
*Nutritional Yeast (tastes good in stuff)
*Homemade kefir (not sure if water kefir provides the same B12 benefit so this only applies to milk kefir.)

This is by no means a complete or exhaustive list; these are just a few of my own favorite B12 whole food sources.

Oh, and last time I checked, not only was I not a chimpanzee, I wasn't a neanderthal, either. Are you?

Cheerio!

maxwell said...

@soohum

Please explain to all of us what the Maasai, Inuit, Aborigines, Plains Indians, Polynesians or in fact any indigenous tribe in any location around the world ate before they were contacted by Europeans.

Tell me when you find a non-flesh eating people (this includes: seafood, insect, flesh meat or dairy).

We'll just wait here till you get back from your hunt (no pun intended).

;)

jdwltr said...

I know I am pretty late to the game here - but I love the post. I have no formal training in any of these areas, just a lingering curiosity revolving around proto-human culture.

That said, I did a cursory look at the notion of potential B12 deficiencies in strict vegan diets and my rudimentary logic would lead me thus:

IF B12 is critical to the functioning of the human organism, in particular cell metabolism and DNA synthesis, AND it isn't readily available in any foodstuff other than meat, THAN the argument that man is a herbivore is fundamentally flawed.

popimaster said...

First of all, just because our ancestors did something, doesn't mean we should. They dealt with what was available. People in Africa didn't have access to tropical fruits that grew in south america like today.

After all average lifespan was 30 years back in those days.

Maybe eating dead corpse isn't the optimal for our organism ? yes our organism learnt to deal with digestion of it for the use of survival, but it's just for emergency cases, other than that he can get all its vital energy required from fruits and vegtables which are pure and instantly provide energy to our cells.

Best diet is 80% raw food oriented - sometimes with animal products

The ok diet is whole food oriented- focused around paleo nutrition and lots of animal products with vegtables

The worse diet is processed junk diet

I personally started at the bottom, and now starting to climb up towards the raw diet from the paleo diet, cause I still get sick and don't feel very well on such animal loaded diet. I will try to reverse things and eat more fruits, vegtables and nuts, and less meat, eggs, cottage.

Rodney said...

For those concerned about B12 and vegans, it's good to note that B12 is not found in any natural plant-based foods. Search the Internet and you'll see that even several vegan societies say this.

But you have to ask yourself where do the animals we eat get their B12?

It turns out they get it from dirt. B12 is found in soil. Animals eat it and it gets stored in their tissues. We eat them and get some of their B12.

How would any vegan ancestors get their B12? They might get it from eating root vegetables that would not be thoroughly cleaned of dirt.