Thursday, September 1, 2011

Catching Fire

Catching Fire by Richard Wrangham presents a compelling argument that the primary nutritional change driving human evolution from small-brained Homo habilis to large-brained Homo sapiens was cooking––not meat-eating.

Wrangham starts off with some critical observations:  No known human tribe lives on a predominantly raw food diet, and those modern people who attempt to live on a largely raw food diet have demonstrated difficulties maintaining body mass, energy levels, and fertility.  This points to the hypothesis that modern humans are actually "adapted to eating cooked food in the same essential way as cows are adapted to eating grass, or fleas to sucking blood, or any other animal to its signature diet.  We are tied to our adapted diet of cooked food, and the results pervade our lives, from our bodies to our minds.  We humans are the cooking apes, the creatures of the flame."

Traditional Chinese medicine has for milennia maintained that humans need to eat cooked food to get adequate food energy (Pinyin: gu qi).  In The Tao of Healthy Eating, traditional Chinese physician Bob Flaws writes:

"Traditional Chinese medicine suggests that most people, most of the time, should eat mostly cooked food.  Cooking is predigestion on the outside of the body to make food more easily digestible on the inside.  By cooking foods in a pot on the outside of the body, one can initiate and facilitate the stomach's rottening and ripening in its pot on the inside of the body.  cold and raw foods require that much more energy to transform them into warm soup within the pot of the stomach.  Since it takes energy or qi to create this warmth and transformation, the net profit from this transformation is less.  Whereas, if one eats cooked foods, less qi is spent in the process of digestion.  This means that the net profit of digestion, i.e. qi or energy, is greater."

This perspective contradicts the common belief that raw food is better than cooked because cooking can destroy nutrients.  But as Flaws points out,  net nutrient delivery matters more than gross amount of nutrient in the raw food.  Let's assume that a carrot has 10 units of X nutrient, but only 10% of it is available to humans because it is locked in an largely indigestible cellulose envelope.  Let's say that cooking destroys 50% of that nutrient (a gross overestimation for proper cooking), but increases the availability to 50%.  The net delivery of X from the raw carrot is 1 unit, but the net from the cooked carrot is 2.5 units. 


Wrangham presents multiple lines of evidence that humans and non-humans have a greater net macronutrient absorption from cooked than from raw foods, resulting in cooked foods delivering more energy than raw foods.

Wrangham includes some of the research I discussed in my series on raw vegan diet, which found that a high proportion of people eating diets high in raw foods (70% or more raw) are underweight and have low fertility.   Belgian researchers showed that humans can digest only about 65% of the protein in raw eggs, but 91-94% of the protein from cooked eggs. [1] Another team showed that enzymatic  digestion of heated beef protein increased by four times over raw beef protein. [2] This occurs because cooking denatures protein more effectively than stomach acid, making it more vulnerable to enzymatic digestion.

Wrangham's hypothesis competes with the Man-The-Hunter hypothesis which maintains that humans evolved big brains and small guts by route of increased meat-eating.   However, Wrangham points out that the hunting hypothesis can't account for some of the facts. Increased meat-eating might explain the transition from Australopithecines to Homo habilis (habilines), but not the transition from the habilines to Homo erectus:
"Meat-eating accounts smoothly for the first transition, jump-starting evolution toward humans by shifting chimpanzeelike australopithecines into knife-wielding, bigger-brained habilines, while still leaving them with apelike bodies capable of collecting and digesting [raw] vegetable foods as efficiently as did australopithecines.  But if meat eating explains the origin of the habilines, it leaves the second transition unexplained, from habilines to Homo erectus.  Did habilines and Homo erectus obtain their meat in such different ways that they evolved different kinds of anatomy?  Some people think the habilines might have been primarily scavengers while Homo erectus were more proficient hunters.  The idea is plausible, though archaeological data do not directly test it.  But it does not solve a key problem concerning the anatomy of Homo erectus, which had small jaws and small teeth that were poorly adapted for eating the tough raw meat of game animals.  These weaker mouths cannot be explained by Home erectus's becoming better at hunting.  Something else must have been going on."
Increased meat eating can't explain whey we have such small mouths and jaws. 
"Given that the mouth is the entry to the gut, humans have an astonishingly tiny opening for such a large species....To find a primate with as relatively small an aperture as that of humans, you have to go to a diminutive species, such as a squirrel monkey weighing less than 1.4 kilograms (3 pounds). In addition to having a small gape, our mouths have a relatively small volume––about the same size as chimpanzee mouths, even though we weigh some 50 percent more than they do.  Zoologists often try to capture the essence of our species with such phrases as the naked, bipedal, or big-brained ape.  They could equally well call us the small-mouthed ape."
Compare the jaws of any raw food eating animal to human jaws.  The largely vegetarian chimp has a gape much larger than that of a human:
Source:  Junglewalk

The carnivorous cat has a gape nearly half the size of its head, and the jaws are very powerful for cutting through raw meat. 

You can see some other big yawns here.  Compare to the modern human gape:


Source:  Flikr
Humans have a small mouth for such a large head.  The larger gape of other species is not for taking in large bites, it is necessary for leverage to crush tough, chewy raw foods. 

By the way, although Wrangham does not mention it, the shrinkage and reorganization of the mouth laid the foundation for speech.  Thus, we may owe our linguistic abilities to the mastery of fire and cooking.  I seem to recall reading that another anthropologist had proposed this hypothesis more than 20 years ago, but I no longer have the book that had the reference.

If evolution from Homo habilis to Homo erectus had been driven by increased consumption of raw meat, with technology and cooking as an afterthought, we would expect to have seen it maintain the large powerful ape mouth and jaws, retained the large, sturdy teeth, and increased the shearing action for adaptation to meat eating.  Instead, from the habilines to the erectines the mouth and teeth shrank.

Here's a habiline skull:

Source: www.anhb.uwa.edu.au/.../ skulls/s10_homo_habilis

And here's an erectine skull:
Source: www.ma.krakow.pl

The erectine jaw and teeth are much smaller relative to body size.  Erectines had a smaller gape and must have had a softer diet than the habilines.  The skeletal remains provide the best available evidence that some tribe of Homo habilis discovered something that made for a much softer and energy-rich diet, giving rise to Homo erectus. 

One might think that the use of knives and hammers alone selected for smaller mouths.  Perhaps habilines simply cut the meat into small pieces or pounded it tender.  Although initially plausible, on further examination, this loses credibility, because it can't explain how an animal adapted to a diet consisting predominantly of raw vegetation can continue eating that vegetation while adapting to the raw meat portion of the diet.

Wrangham notes that "Peter Lucas has calculated that the size of a tooth needed to make a crack in a cooked potato is 56 percent to 82 percent smaller than needed for a raw potato."  Thus, so long as human ancestors continued to eat raw plants, they needed large teeth and jaws.  And they definitely needed to eat plants.
"The problem is that tropical hunter-gatherers have to eat at least half of their diet in the form of plants, and the kinds of plant foods our hunter-gatherer ancestors would have relied on are not easily digested raw.
Tropical wild game simply does not provide adequate amounts of fat or carbohydrate to prevent excessive intake of protein resulting in ammonia and urea accumulation, especially in the annual dry seasons, when the whole carcass fat levels of game will drop as low as 1 percent to 2 percent.
 
By the way, Wrangham notes:
"Starchy foods make up more than half of the diets of tropical hunter-gatherers today and may well have been eaten in similar quantity by our human and pre-human ancestors in the African savannas."
Moreover, if raw meat was a staple of our ancestors, we would expect modern humans to have some significant resistance to toxins produced by bacteria that infect raw meat.  But we are still vulnerable to those bacterial toxins.

In addition, there is a major economic problem with the meat-eating hypothesis.  Wrangham has studied chimps directly, watching them hunt and eat.  The typical chimp has to spend about 6 hours daily chewing its bulky, chewy raw foods.  They hunt opportunistically, but will only spend 15 to 20 minutes on a hunt.  If not successful in that time frame, they give up and return to eating plants.  Why?

Wrangham explains that because digestion of raw food takes more time than digestion of cooked food and costs a lot of energy, a chimp has to devote eight or nine hours daily to feeding in order to get adequate energy.  Australopithecines and habilines probably had similar constraints.  This would have prevented them from investing much time in hunting:
"Males who did not cook would not have been able to rely on hunting to feed themselves.  Like chimps, they could hunt in opportunistic spurts.   But if they devoted many hours to hunting, the risk of failure to obtain prey could not be compensated rapidly enough.  Eating their daily required calories in the form of their staple plant foods would have taken too long."
As Wrangham explains, a division of labor into hunting and gathering would not solve this problem, so long as the food was consumed raw.
"Suppose that a hunter living on raw food has a mate who is willing to feed him, that his mate could collect enough raw foods for him (while satisfying her own needs) and would bring them back to a central place, to be met by her grateful mate.  Then suppose the male has had an unsuccessful day of hunting....The hungry hunter needs to consume, say, two thousand calories, but he cannot eat after dark.  To do so would be too dangerous, scrabbling in the predator-filled night to feel for the nuts, leaves, or roots his gatherer friend brought him.  If the hunter slept on the ground, he would be exposed to predators and large ungulates as he fumbled for his food.  If he were in a tree, he would find it hard to have his raw foods with him because they do not come in tidy packages.  
"So to eat his fill he would have to do most of his eating before dusk, which falls between about 6 and 7 P.M. in equatorial regions.  If he had eaten nothing while on the hunt, he would need to be back in camp before midday, and there he would find his mate's gathered foods 9assuming she had been able to complete her food gathering so early in the day).  He would then have to spend the rest of the day eating, resting, eating, resting, and eating.  In short, the long hours of chewing necessitated by a raw diet would have sharply reduced hunting time.  It is questionable whether the sexual division of labor would have been possible at all.

"The use of fire solved the problem.  It freed hunters from previous time constraints by reducing the time spent chewing.  It also allowed eating after dark.  The first of our ancestral line to cook their food would have gained several hours of daytime. Instead of being an opportunistic activity, hunting could have become a more dedicated pursuit with a higher potential for success.  Nowadays men can hunt until nightfall and still eat a large meal in camp.  After cooking began, therefore, hunting could contribute to the full development of the family household, reliant as it is on a predictable economic exchange between women and men."
 In short, cooking (and other culinary technologies that make food softer and easier to digest) made it possible for humans to pursue increased meat-eating.  It freed men from the need to continuously feed on plant foods, giving them time to devote to hunting meat. 

Simply put, cooked food delivers more energy and nutrition in a smaller, more easily digested package than raw food.  Wrangham argues that since Homo erectus had a larger brain and a much smaller face, mouth and teeth than Homo habilis, probably some tribe of Homo habilis first controlled fire and used it for cooking.  The resulting increase in energy and nutrient availability led to rapid selection for smaller guts and larger brains and bodies.  By providing protection from nocturnal predators, control of fire also enabled human ancestors to give up tree-dwelling.  It also supported the sexual division of labor (hunting and gathering/cooking) present in human cultures.

Wrangham's Catching Fire will provide plenty of food for thought for anyone interested in ancestral nutrition. 

36 comments:

VICTOR said...

Interesting article, I have a question, how good is the assimilation of raw salmon (previously frozen) compared to meat, I eat salmon of this manner because is much more comfortable, the problem is only with the protein of the fish or there is a problem with assimilation of DHA+EPA, Vit D and iodine too?
there is a problem in eat some ounces of frozen raw pink salmon daily?
Thank you

VICTOR said...

Hello
Interesting article
I have a question, how good is the assimilation of frozen pink salmon eating raw, the problem is only with the protein or as in vegetables it affect to the assimilation of dha+epa,vit d and iodine?
I don't have time for cooking, is much more comfortable for me.
Are there other problems eating some ounces of raw salmon daily?
thanks

Don said...

Victor,

I don't have data, but probably, we derive less of all nutrients from raw than from cooked meat, because poor digestion of the protein would reduce access to other nutrients. Most of the nutrients in meat are locked inside muscle cells, composed of proteins and fats. To access the cell contents, we have to digest the proteins in the cell walls. Since protein digestion is less efficient when the proteins are raw, we would degrade less of the cell walls, resulting in less access to the nutrients in the cell walls as well as in the cytoplasm.

When we cook meat, it releases its juices...that juice is the nutrient-rich cytoplasm. Raw meat doesn't release its juices to the extent of cooked meat. So, I think you probably don't get as much out of that salmon eaten raw, as you would if you cooked it.

Taylor said...

Catching Fire was a great book. Loved your talk at AHS. You're still 'Paleo'. You just disagree on how much meat our ancestors likely ate. That doesn't mean you aren't paleo. If you distance your self from paleo the unstated implication is that your recommendations are not informed by evolution. That's the wrong message. I wish that instead of your goodbye to paleo post you had framed it as 'I no longer think our ancestors consumed tons of meat and so no longer believe that a diet to mimic our paleolithic ancestors should not contain 80% calories from meat.

BTW a diet 50% meat by calories is more like 20% meat by volume. That's about what I do.

FredT said...

Raw, fish or meat, is a good way to get parasites.

Your choice.

Ed said...

I don't get all the shadow boxing. You seem to have written this article as a sort-of letter to someone with whom you're having an argument. The other person I guess thinks that cooking had nothing to do with our current design, that it was all about meat consumption. You seem to be pushing back the other direction, that it was mostly about the cooking.

I personally find the shadow boxing to be distracting and extraneous. My take-away (and this is a very interesting topic, thank you for writing about it) is that the combination of eating up on the food chain plus cooking is what made us human. From your post, it seems that each activity magnified the impact of the other.

It is interesting that eating meat came first. I wonder if we had mastered fire first, would we have become hunters? Or, maybe, we had to start adapting as hunters to get smart enough to master fire? How did the fire skill spread among early humans? Maybe I should read the book :-)

Andrew Wallace said...

Nice article. It all eems very plausible. Although you mostly focused on meat, I'm sure one of the main changes that fire brought on was access to the otherwise largely indigestible world of roots and tubers... starch! Fruit, leaves and shoots --> meat, seeds and roots.

Don said...

Ed,

Shadow boxing? I simply presented the outline of Wrangham's argument, and when you read the book, you will find that he presents it in the same way, because he is presenting a hypothesis that competes with the hunting hypothesis.

I think most anthropologists agree that all prehumans hunted to some extent, just as do chimps. The hunting hypothesis is that increased meat-eating accounts for the dramatic evolutionary changes from the australopithecines to modern man, and often proponents of that hypothesis maintain that use of fire came only within the last 300 K years.

Wrangham's hypothesis is that increased meat-eating alone may have taken us no further than Homo habilis. Since vegetarians can maintain adequate energy intakes so long as they cook, this suggests that meat eating was of importance primarily as a route to increased energy acquisition. Mastery of cooking made it possible to increase meat consumption, and also made meat consumption less important from an energy standpoint.

john said...

I've never seen anything too convincing either way [USOs vs meat], but it's somewhat illogical to use the 65-mil-year-98% [human/chimp dna] argument for diet followed by a pro-cooking idea.

Don said...

Andrew,

We actually have pretty good evidence that australopithecines and habilines consumed roots and tubers. They were most likely equipped like chimps for hind-gut fermentation, so raw roots and tubers were digestible to them. The Wrangham hypothesis suggests that adoption of cooking enabled human guts to shrink because we no longer had to ferment our plant foods in our guts.

In other words, our ancestors have eaten roots and tubers all along, but through evolution we shifted from consuming them raw and processing them in our hindguts, to cooking/predigesting them so that the hindgut fermentation became unnecessary. So through the use of fire we changed from critters who could digest raw starches (by hindgut fermentation) to critters who can't digest raw starches, but rely on cooked starches. Our lineage kept using the same foods but changed the way we digest them.

Don said...

John,

Not at all. The DNA overlap tells us we share adaptations, including nutritional adaptations, with the chimps. However, we have a 2% difference, and in that would lie the adaptations to cooking, including skeletal and gut changes.

As I wrote in response to Andrew, cooking may have only changed how we digest foods, not necessarily what foods we ate. No doubt, in fact. If habilines were the first to cook, then they no doubt cooked the foods they already ate: fruits, vegetables, legumes, tubers, meat (including insects), nuts. They didn't adopt an entirely new diet.

So the baseline adaptation would be to foods consumed for millions of years. Cooking only modified the digestibility of those foods....it didn't change the diet entirely. And, since cooking changed foods in certain ways, humans became adapted to the cooked versions of those foods. For example, chimps can tolerate fruits we can't stomach because they are so full of secondary 'toxic' compounds. So we adapted to the "detoxified" i.e. cooked versions of the same foods eaten by our primate ancestors.

Don said...

Ed,

BTW, Wrangham addresses your questions in the book. Modern chimps (e.g. Kanzi) can learn to start and tend fires, and cook foods, so it is doubtful that increased meat-eating (beyond chimp levels) was a prerequisite for learning that skill. But increased energy intake certainly was a prerequisite for brain expansion and it is possible that, absent cooking, increasing the meat portion of the diet provided just enough extra calories to support the expansion to the habiline brain (50% larger than a chimp).

Ezer said...

Well said. In my mind, I've always believed more in the hypothesis of cooked tubers and meat (when available) driving human evolution than just raw meat.

My rationale is: If two very improbable events occurs, then there must be a causal effect.

Very rare event A = cooked food;
Very rare event B = the appearing of an animal with big brain, small gut and small non-meat specialised teeth.

It must be that event A largely caused event B.

Anand Srivastava said...

Incredible post. For a long time I had been disappointed with the content of the posts. But this is one of those posts that we love you for.

I had thought that cooking provided more starch to humans, but didn't realize that cooking was necessary for humans to transition to hunting and gathering.

Anya said...

Don,

nice article, thanks.
What is your thought on juicing (vegetables).
In theory it provides comparable absorption efficiencies as cooking while not degrading enzymes/nutrients (if you drink within minutes after juicing).

There is a lot of anecdotal evidence that including juicing as part of you diet is beneficial.

BTW I agree that you are still paleo, you just don't agree with the mainstream high fat high protein crowd. In summer I agree with you, in winter not so much.
(we do not all live in the tropics)

David said...

Great review and thanks for bringing this to everyone's attention.

Phoenix said...

Great post, Don.

I could be wrong, but aren't B-vitamins deactivated in the cooking process? Could a person potentially become deficient in B-vitamins if they are eating mostly cooked foods? Or do the foods we eat raw (fruits, avocados, nuts and seeds) compensate for this?

Alan said...

Excellent stuff.

Thanks for addressing the burning problem of Americans not absorbing enough calories.

Don said...

Phoenix,

The following B-vitamins are most heat-sensitive:

Thiamin B1
Pantothenic acid B5
Pyridoxine B6
Folate

These are less heat sensitive:

Riboflavin B2
Niacin B3
Cobalamin B12

The heat-sensitive ones withstand moderate cooking. Moderate cooking means just enough to make juices flow out; this is enough to break down the cells without doing a lot of damage to the nutrients. Cooked greens, tubers, roots, meat, and roasted nuts would supply the majority of B-complex vitamins. Again, the net is more important than the gross.

I don't recommend eating much of raw nuts. Roasting or blanching/boiling makes them more digestible and nutritious.

Don said...

Anya,

With juicing you typically lose ~50% of the nutrients present in the raw food in the pulp. This is no better than proper cooking. In fact, with proper cooking, you can have less total nutrient loss. Proper cooking will destroy less than 50% of the nutrients present in the raw food, while increasing digestibility and assimilation by 50% or more.

Traditionally, winter foods include roots and tubers easily stored in underground caches, which evolved into root cellars prior to the industrial refrigeration evolution. Hunter-gatherers in temperate climates got starchy tubers from wetlands in late autumn and dried and stored them for winter; they also could harvest those tubers in winter. Winter fare consisted of long-cooked stews of plants and animal matter combined.

Don said...

Alan,

I wasn't addressing any problem except understanding what our ancestors ate.

You might want to read the last chapter of Catching Fire. It discusses why Americans get too many calories from their foods.

Its obviously not because we eat cooked foods. The Chinese and Japanese eat little or no raw foods, and lots of cooked starch, yet they avoid the high rates of obesity we see in the U.S.

The problem is that in industrialized nations we have gone too far in food processing, making foods too soft and easily digested, while adding lots of easily digested fats to those soft foods. In short, we have foods with energy density and digestibility not found in primitive diets. Like donuts versus coarse whole grain bread.

From Sims and Danforth:

"It is now apparent, at least
in the short term, that an increase in quantity of fat in the diet
is a more critical factor than a comparable increase in that of
carbohydrate in determining whether the stores of triglyceride
in adipose tissue will be increased (48)."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC424278/

Yep, it really is about energy and fat balance, with pure fats and oils and refined carbohydrates having the highest energy densities available. Simply:

1. It is easier to overconsume calories from fat or high fat foods because fat is most energy dense (9 kcal/g) and least bulky of all foods we consume (2.5 times more energy dense than pure sugar). This effect varies with context. High fat diets more easily produce energy overconsumption in people with low energy requirements (small, female, or low activity levels), less so for people with high energy requirements (large, male, or high activity levels). Context.

2. Dietary fat is easier to digest and assimilate than many whole food dietary carbohydrate sources (>90% digestible vs. < 90% digestible).

3. Dietary fat has no thermogenic effect, whereas 10% of dietary carbohydrate and ~25-30% of dietary protein is lost to thermogenesis.

4. There is no way to store excess dietary fat except as body fat, whereas dietary carbohydrate can be and usually is stored as glycogen.

5. The energy cost of storing fat as fat is ~3% of the calories in the fat, whereas converting carbohydrate to fat costs ~25% of the calories in the carbohydrate.

All this adds up to dietary fat being the nutrient most likely to get stored as body fat. That doesn't mean dietary carbohydrate doesn't play a role. Pure sugar provides 4 kcal per g, ~4 times the density of cooked rice, potatoes, or sweet potatoes. The more finely ground the carb, the more digestible. The higher the digestibility and concentration of dietary carbohydrate, the higher glycogen stores go, and the lower the basal rate of fat oxidation. So high density carbs indirectly suppress fat oxidation by raising glycogen stores.

Gordon said...

Excellent review Don. Have you had time to consider the types of plant underground storage organs in the Turkana basin? It'd be fascinating to identify the starch sources for early homo sapiens and homo erectus and consider their nutrient profiles after cooking. There's got to be more to primal eating than sweet potatoes and yams:)
Keep up the helpful posts, and more helpful comments
ps
Wrangham was featured in a documentary a couple years back that did a very good job of the human meat-cooking tradition. Let's face it, some people don't read non-fiction books, but enjoy watching tv.

blackflag said...

It is interesting that sushi, the most common form of raw meat, is almost always eaten with something acidic like pickled vegetables.

I wonder how much this helps to break down the protein and extract more nutrients.

VICTOR said...

Hello Don, I have two questons

You cited
"4. There is no way to store excess dietary fat except as body fat, whereas dietary carbohydrate can be and usually is stored as glycogen."

Fat can be stored to some extend in the muscles, not inmediately under the skin
that doesn't afect esthetics, is this correct? if this is correct I don't see this advantage clear unless the room for fat is less than the room for carbohydrate in the muscles
Is there less room for fat in the muscles than for carbs?

What About fructose, goes to fat directly? the cost of convert it to fat is the same?

Thanks

Peter said...

Don, Interesting entry. However, I dare to say that there two reasons why raw-fooders have failed in the past a) too little calories, b) too much fat. It's not uncommon for US raw (gourmet) foodies to have 70% of their calories coming from fat. This together with little amount calories and one is on the deep end.

Forget David Wolf and the spiritual, low-calory/high fat potion/lotion/mushroom crew, There's new generation of low-fat raw vegans who have managed to sustain the lifestyle for years, some even decades (Douglas Graham, Michael Arstein, Durinrider, etc).

First time in the history we are actually seeing raw-fooders succeed, the common factor is plenty of calories (3000-6000 per day) together with very very low-fat regime.

I would like to see you doing a review on Douglas Graham epic classic "80/10/10".

Thanks

"Fruitarian athletes thriving and breaking records"
http://www.fitnessgoop.com/2011/08/fruitarian-athletes-are-thriving-and-breaking-records/

Don said...

Peter,

These modern fruitarians succeed to an extent only because modern fruits have a higher energy concentration, and much lower fiber content, than raw fruits. Wrangham has spent a lot of time in the field with chimps in Africa. He has tried every fruit he has seen them eat. I don't have the book with me right now, but if I remember correctly, out of 10s of fruits chimps eat, Wrangham found only 2 of tolerable flavor, and all require considerable chewing.

Modern fruitarians rarely restrict themselves to local fruits, but our African ancestors could only eat what was in their local environment.

You said it yourself:
"First time in the history we are actually seeing raw-fooders succeed,..."

If we were adapted to raw diets, why would this be the first time in history? For thousands of years, no one could do it, but suddenly some succeed? This clearly supports that we are adapted to cooked food, and modern raw fooders only succeed because they have a particularly favorable circumstance in modern industrialized nations with intercontinental transport and relatively low energy requirements.

If it works for you, keep doing it until it doesn't.

Don said...

Victor,

First, the point is about obesity. We can store carbohydrate as glycogen rather than as fat, but we can only store fat as fat. Thus, any excess dietary fat can only go to fat stores, it can never go elsewhere.

Second, the liver can convert fructose to glucose, and fructose is used to replenish liver glycogen before the liver will convert it to fat.

Third, the energy cost of converting fructose to fat is similar to the cost of converting glucose to fat.

Fourth, intramuscular fat infiltration occurs secondary to adipose accumulation, not prior to. Fat infiltrates muscles only if an animal is kept inactive and has already accumulated fat outside the muscle. This is in part why grass-fed and wild game meat have low fat contents compared to conventional meats.

Peter said...

"If we were adapted to raw diets, why would this be the first time in history?"

Good question, but the answer is again simple.

First time in the history a typical Westerner can actually choose to eat nothing but fruits and greens. Since we emerged out of the equator, it didn't work anymore. Now it does, there's abundance of cheap fruit in stores to choose in the Northern hemisphere.

I simple do not buy the fact raw-foods are unsustainable, that's poor reasoning. Whether it's optimal diet is another issue. Why people have screwed it up in the past is ridiculously easy to explain: too much fat (avocados, nuts, coconut oil) too little calories and too little greens. These modern fruitarians who can pull it off and thrive typically consume atleast pound of green leafs per day, keep it low fat and eat heaps of calories. There's even website called 30bananas a day, indicating that the base calory for average raw-foodist should be atleast 3000k.

Take a look at Douglas Graham, 30 years of nothing but raw foods, (macroratio around 80/10/10, 80 for carbs that is)

Dr Dougs fittness stunts
http://www.youtube.com/watch?v=Vzk-jh1eemI

So, saying that one cannot thrive and succeed on raw-food is just BS. More and more people are learning how to do it correctly.

Also, I am bit skeptical over the notion of modern fruits being more calory dense. That's a theory. There's some solid data over wild paleo fruits and Africa and Asia showing no significant difference compared modern market fruits.

As said, I'd love to see you doing a review of Douglas Grahams 80/10/10.

Don said...

Peter,

If wild fruits aren't more fibrous and difficult to chew, then why do chimps have such large mouths and chewing muscles?

If humans evolved on raw fruit and greens available in Africa, why don't we have jaws, mouths, and teeth like chimps or gorillas, the former of which eats 75% raw fruit, 20% raw leaves, the latter about the reverse?

If its all about location, then why didn't all native equatorial Africans historically eat diets of raw fruits and greens? Why would they all go to the trouble of collecting fire wood if its so easy and natural for humans to live on raw fruits and greens available in Africa?

I don't think there is any evidence supporting the idea that humans are adapted to a raw fruit and vegetable diet. Yes, some people can do it in modern circumstances, but our ancestors had a different context to adapt to.

Take away clothing, fire, and all other modern methods of conserving body heat and reducing caloric expenditure, and a modern raw fooder would need more than 3000 kcal per day.

The clinical research clearly shows a high incidence of underweight, amennorhea, B12 deficiency, and anemia in raw fooders. Even the Durianrider has reported B12 deficiency.

It also clearly shows that cooked foods are more digestible and deliver more energy in smaller packages.

The evidence is piled against humans being adapted to raw plant food diets. The modern raw fooder is in an exceptional circumstance unlike that of Homo erectus.

Peter said...

You made good point, there. I myself do not believe in the raw theory and I cannot let your points go aside. However, I found that I do very well when the bulk of my calories come from fruits, the rest from the starches.

"The clinical research clearly shows a high incidence of underweight, amennorhea, B12 deficiency, and anemia in raw fooders. Even the Durianrider has reported B12 deficiency".

Indeed, and who are those clinically tested? It's the 1500 calories a day/ 70% fat crew. The raw-community (have) had the same food bias as everyone else "carbs make you fat", "fruit raise your triglycerides and gives you diabetes", etc. This mindset while being raw, and you are doomed to fail.

Durianrider did his vegan thing for 8 years without a single supplement. He has been clinically diagnosed as lacking the intrinsic factor for b-12 absorption. In todays sanitized and sterile environment B-12 should be an issue no matter what diet you are on.

Duke of Earls said...

Sounds like a fascinating book. It certainly makes sense that those of our ancestors who adopted cooking would have a selective advantage given their increased energy levels.

Don said...

Peter,

because of the efficiency of B12 recycling in humans, many B12 replete individuals can go 10-20 years without B12 in the diet.

Interesting that Durianrider wasn't deficient in intrinsic factor until after 8 years on a vegan diet. He lists his age as 33, so he must have gone at least 22 years before that without B12 or intrinsic factor deficiency.

So I have to ask, why does he develop "intrinsic factor deficiency" after 8 years as a vegan, but not during the 22 years previous to that? How does that happen?

Peter said...

Durianrider was diagnosed with Chron's disease. He had never even checked his B-12 levels until he became vegan. I don't understand what's the issue with this, 99% of professional meat-eating body-builders take b-12 supplements. Lance Armstrong shoots b-12 injections. Mark Sisson sells them. Is there paleo merchants who do not sell or promote b-12 supplements?

I recommend a book about the topic "Could it be B-12"

http://www.amazon.com/Could-Be-B12-Epidemic-Misdiagnoses/dp/1884995691

Don said...

Peter,

Typically Crohn's disease affects the intestines, which would have no effect on intrinsic factor production in the stomach, but if he has atypical Crohn's disease, this could affect his B12 absorption. But a vegan diet does not provide adequate B12 anyway.

Not sure about your BB stats, but in any case, professional BBs do a lot of stuff that is unnecessary, including taking supplements of B12. Their behavior doesn't prove that anyone needs B12 supplements.

My point about Durianrider is that he went ~22 years without developing B12 deficiency, but developed the deficiency when eating a vegan diet. So if someone goes 22 years without B12 or intrinsic factor deficiency, then has both diagnosed after adopting a vegan diet, I would initially suspect that the vegan diet caused the deficiencies.

I didn't at the time know that he had Crohn's disease, which might explain his lack of intrinsic factor.

The Crohn's may be responsible for the IF deficiency, but it is not responsible for the fact that his chosen diet does not supply adequate vitamin B12. Even if he had normal IF, his diet would still lack B12 and he would still likely develop B12 deficiency. You can't blame IF deficiency for the absence of B12 in the diet.

Studies show that IF deficiency does not completely prevent B12 absorption. For example, this study

http://www.aafp.org/afp/2003/0301/p979.html

showed:

"Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective. "

There exists an alternative absorption route for B12.

Thus, even Durianrider can't blame IF deficiency for B12 deficiency. If his diet had adequate B12, his IF deficiency would not matter. It is his failure to eat foods that supply B12 that is the main cause of his B12 deficiency.

Some natural foods are extraordinarily high in B12, e.g. liver and some shellfish. These would be alternatives to taking pills. In fact, before B12 was isolated, pernicious anemia was routinely treated with liver extracts.

gwarm said...

What do you make of this theory ... people always say 'eat for fertility' for the best diet but there is 'pleiotropy theory of aging':
"This system is highly likely to remain the way it has evolved
because of the antagonistic pleiotropy theory of aging, which asserts
that selection for early reproductive success permits deleterious
effects on fitness in later life because genes that are operative during
development are also operative in later life, but exert different effects
on health.26 Indeed, because the lack of negative feedback ensures
maintenance of the drive to procreation mediated by testosterone,
the present evolutionary state (without a mechanism of limiting
free T) may already represent the desirable ultimate of evolution as
far as propagation of the species is concerned."

Text is from 'acne and cancer.pdf': http://robbwolf.com/2011/09/13/the-paleo-solution-episode-97/#comment-47146)

Gerald said...

Thanks for the post, this was a very interesting book for me, I've read Catching Fire several times because I wanted to retain all of the information. I'd likel to see how people like Doug Graham resopnd to it. I've watched all of Wrangham's videos I could find, I love his personality. I think he has intellectual integrity and is just trying to go where the science leads. What he writes mirrored my issues on raw food. I felt healthy the whole time on trying a raw diet over several years but spent a lot of time and energy on food, had to resist the delicious aroma of cooked.

Let us not forget a lot of the food raw fooders eat is the best of the best, unavailable in nature, and i#d like to see a raw food evangelist live and survive just one month in nature, let them pick the spot, without fire, and get enough calories, let alone keep warm, and not turn to eating meat. some could say- ok it's not natural or at least historic per se eating these high quality fruits, but still now that we can, it's the healthiest, even more than starch. Perhaps, then go for it guys. try it

I thought he was honest and open and so was I. I read it thinking I would catch errors in thinking, intead I was blown away. I didn't feel bad on raw food, physically, but I feel good now on a cooked starch based diet fine tuned (free of nightshades) and still high in fruits and vegetables. I feel just as good. Raw food might be a de facto elimination diet

Also raw fooders tend to be right about the importance of being connected to nature. Raw food is not necessarily a "return to nature" I think, having read this book, but we need to return to nature to be our best, or at least, we are in a society of technostress. It is nice to be by the trees, to pick fruit once in a while, to forage, hike, stay fit, and have community. I think eating raw food is natural and also eating cooked food isnatural, and a much easier simpler (and histocially necessary) way for us to get our calorie needs met. Now we can do so from the best of the best fruits, but raw food is not really more "natural" to the human species. we also need fire in other aspects, for warmth and protection so good post, I am interested in this and I still have an open mind I hope