paleolithic

 Hands down the best health book I read this year was The Definitive H.P. Lovecraft: 67 Tales of Horror in One Volume. Despite being about fictional creatures of terror from unholy abysses, I learned quite a bit from Lovecraft's depiction of the universe. The humans in Lovecraft's stories are baptized into the knowledge that the universe is older and more incomprehensible than they could have ever imagined. While the monstrosities and sublime ancient temples are quite terrifying, what is even more terrifying to the humans in the stories is their realization of how little they can ever really know. Those that get a taste of the mysteries often only do so at a very high price. 

They called up some image from deep cells and tissues whose retentive functions are wholly primal and awesomely ancestral

I'm not sure I have any sort of particular cause in terms of diet anymore. It's gotten to the point where I'm just interested in the Paleolithic and not really very concerned with arguing about whether or not a potato is safe to eat or not. 

Wouldn't it be nice if our nice little narratives worked out? The ones in which Homo sapiens sapiens is the protagonist and you can trace his illustrious evolution neatly through the ages. And he fits rather nicely in your romantic stories about hunters and mammoths so you can tell people that this is their heritage. 

But in reality you don't get your nice story. Instead, you get ages and ages of dust and bones, in which every little shred of a skeleton is a prized, but dim, glimpse into ages long past. 

In my anthropology class last year, one of the skull casts that caught my attention was the Kabwe skull, which is estimated to be between 125,000 and 300,000 years old. Not quite Homo Sapiens, the skull has some features of modern humans and some of Neanderthals. Homo rhodesiensis? Homo heidelbergensis? Homo sapiens rhodesiensis? Anthropologists could argue about it all day. Either way, this person died a miserable death. The first known incidence of dental infection in a hominid as far as I know, and the infection was bad enough to put some ugly holes in the bone and eventually kill the individual. 

There is only so much you can tell from bones, which leaves lots of room for people to make stuff up. Stable isotope analysis seems quite promising, as they can potentially tell you the source of protein in the diet, but they can only tell that and nothing else, and the isotopes are subject to interpretation. For example, Lierre Keith in her error-ridden Vegetarian Myth claims that stable isotope analysis showed Australopithecus africanus ate meat, but in reality the data only said that the protein was from carbon-13 enriched foods, which could include grasses and sedges as well. Later investigations revealed that the carbon-13 probably was more likely from grasses and sedges, but the data is up for interpretation. Before you tear up your lawn to make dinner, it might be worth remembering that Australopithecus africanus is only thought to be a possible human ancestor and was quite a bit different from a modern human. 

That said, stable isotope analysis puts to bed the idea that early Homo sapiens were getting their protein from the Paleolithic equivalent of tofu or the idea that Neanderthals definitely only ate meat (turns out that some ate fish too...maybe). 

"Maybe", "later investigations revealed", "thought to be"- these are things that should give you pause whenever you encounter stable isotopes being used to argue about ancient diets. Have I confused you? Good, now you are less vulnerable to the abuse of bones in the name of various causes one way or another. 

It can be used to estimate the trophic level and origin of the protein, but it cannot tell you whether the person ate a teeny tiny auroch steak and then 17 potatoes or whether they only ate mammoth. It cannot tell you the percentage of protein in the diet. It cannot tell you how much protein in grams. That information was lost when the person died. 

Then there is the use (and mainly misuse) of animal bones and modern data from wild game species to argue various things about ancient diets. I read this latest paper, Man The Fat Hunter, with absolute glee because it uses many of the same questionable methods and comes to an opposite conclusion of many past papers, which overemphasize protein. The questionable method is taking bones of animals possibly consumed by ancient humans and plugging them into an equation with the modern wild game data and then saying this or that about the amount of fat or protein in an ancient diet. In this paper we have elephants featured, which is great, since elephants are very fatty, but unfortunately their presence or absence in bone assemblages is not a food diary. There is no way to know how often elephants were eaten, so there is no way to make an even sort-of accurate conclusion about %elephant and therefore %elephant fat in the diet. Whether or not the hominids in question were able to cook is also a point of contention.

One good thing about the paper is that it does try to address one issue, which is ceilings. In this case, the paper mentions possible ceilings for protein consumption and fiber consumption that could be used to build diet-estimating equations. Unfortunately, there are quite hard to determine, as they are affected by human genetic variation, culture, and environment. For example, there is possible a ceiling on the consumption of raw plant materials based on gut morphology (though if you have only skeletons you can only speculate on this) and toxins, but that ceiling can be raised with access to cooking and processing. To complicate matters further, their food sources may have been things you haven't even thought about eating. You can try to figure it out based on local paleobotany and starch microfossils, which can be hard to read. Once you've established that a microfossil on an ancient tooth is possibly Bromus secalinu, you might be able to figure out a little about how it was processed based on microfossil shape and local conditions and if you have a rich lab you might be able to collect it and do a full nutritional analysis, but you still have no idea how much of the diet it made up. 

And what is the protein ceiling? It depends on the rest of the diet, an individual's health, and possibly genetics. Modern genetics adds some depths to the picture. For example, the fact that genetic adaptations for a starch-based diet seem to be part of fairly recent selective sweeps may give us a clue that Paleolithic human ancestors probably weren't eating mainly starch, but statistical genetics is in its infancy.

But genetic variation can add more confusion if we are talking about what to eat now. Many "paleo" dieters have learned the hard way that they carry alleles for hemochromatosis, which means they can over-accumulate iron, which has some pretty nasty effects. It would be interesting to know where this came from, as it clearly would be a liability if an ancient human ate meat-based diet, but ultimately whether or not Paleolithic hominids carried such alleles in high frequency is irrelevant to the millions of men (and some women) who are at risk. This represents a ceiling for them, though it can be modified through modern medical treatment.

Normal is of limited use if you are on the end of the bell curve- this is where personalized medicine and self-experimentation is important

So while it's not completely true we have no idea what Paleolithic hominids ate. We do have some good clues, but reconstructing the diet is pretty hard. That doesn't stop people from trying, but their results are on some pretty shaky ground. 

My own method, which is about as accurate as some of these equations, is to observe the fact that a medallion of relatively lean wild boar goes absolutely perfectly with a seared hazelnut crust and dollop of mashed celeriac or potatoes cooked in broth. Maybe there is a reason that dishes containing a protein on a bed of delicious carbs AND fat (but not overpowered by them) is so appealing to so many? Who knows. 

 This is one of the better articles I've read lately. It addresses serious errors common to works that cite the Paleolithic and foraging societies at being an apex of human welfare. Some of these errors include 

• the idea that hunter-gatherers worked very little to support themselves and spent most of their time in leisure
• the idea of the Khoisan !Kung San peoples as examples of "Stone Age" foragers

For example Lee wrote that the San "worked" only 20 hours a week. Unfortunately, his definition of work was a little questionable. Turns out they work as much as I do:

investigation revealed that what he defined as subsistence activities occupied adult !Kung for about 2.4 days per week on the average, or for about 20 hours. This rather leisurely work schedule, it is claimed, managed to yield an abundant and nutritionally well-balanced diet. These findings were somewhat puzzling to some anthropologists who have conducted similar investigations in similar societies. Hawkes and O'Connell (1981) observed that the Bushmen figures were one-half to one-fifth of the time required by the Alyawarra, a central Australian foraging group. They expressed some surprise because the !Kung and Alyawarra are very similar in habitat as well as technology. The difference, it turned out, was explainable by Hawkes and O'Connell's definition of work: in their calculations of work, they included time spent in processing food as well as hunting and gathering it...."In addition there are the important tasks of manufacturing and maintaining their tool kit and, of course, housework-for the !Kung this involves food preparation, butchery, drawing water and gathering firewood, washing utensils, and cleaning the living space. These tasks take many hours a week" (Lee 1984:51-52).6 When these tasks are added to "subsistence work," the estimate per week is 44.5 hours for men and 40.1 hours for women. Lee is quick to add that these figures are well below the 40 or so hours per week that people in our own society spend above their wage-paid job doing housework, shopping, and other household chores. What seems to be at issue here is what we mean by terms such as "work" and "leisure" in the context of hunting-gathering societies---or, indeed, in the context of any society.

What about all that time spent lounging about?

And then there are the G/wi Bushmen, who reside in the central Kalahari. According to Silberbauer (1981:274- 78), they spend a good part of the day (from about 10 A.M. to about 4 P.M.) resting in the shade, not because they have "chosen" leisure over work or have limited wants, but because to venture out in the blistering sun for any time would expose them to dehydration and heatstroke. Throughout much of the year, there is little cloud cover to provide some relief from the withering heat; unshaded temperatures can reach 60'C (140'F), and sand temperatures as high as 720C (161 F) have been recorded. During the early summer months, all the G/wi lose weight and complain of persistent hunger and thirst (Silberbauer 1981:274). Hardly a "picnic outing on the Thames."

Also sheds further doubt on how well humans are actually adapated to the savanna. 

What about using the !Kung diet to make inferences about what a healthy Paleolithic diet was?

Truswell and Hansen (1976:189-90) cite a string of biomedical researchers who have raised doubts about the nutritional adequacy of the !Kung diet, one going so far as to characterize one Bushmen group as being a "clear case of semi- starvation." Truswell and Hansen (1976:190-91) themselves have concluded that the data suggest "chronic or seasonal calorie insufficiency may be a major reason why San do not reach the same adult stature as most other people."... although he softened his opposition somewhat by conceding that the smallness of the !Kung might have something to do with undernutrition during childhood and adolescence, and he went on to note that !Kung raised on cattle posts on a Bantu diet of milk and grain grow significantly taller (Lee 1979:291).

This paper also mentions the fact that the vast majority of the !Kung consider mongongo nuts an undesirable fallback food. People who want to exploit the !Kung to talk about the Paleolithic tend to believe that they have been foraging since the Paleolithic and the nearly agropastoral people have had little effect on their lifestyle. I will address more of this myth in later posts, but needless to say, the evidence points to the fact that the !Kung have had trading relationships with agropastoralists and their current state is much more precarious nutritionally than it was in the past.

What is mainly missing from their foraging diet these days is fat:

We hear so much these days about the overconsumption of fat in the modern industrial diet that we sometimes forget how important some level of fat consumption is to normal human growth and the maintenance of healthy bodily functions. Animal fat, says Reader (1998:124) is "the proper measure of affluence.".... Hayden's (1981:421) observation is especially relevant here: "I was astounded the first time I saw Western Desert Aborigines ... kill a kangaroo, examine the intestines for fat, and abandon the carcass where it lay because it was too lean. Upon making a kill, Aborigine hunters always open the intestinal cavity and check the fat content. Virtually every ethnographer with whom I have discussed this observation confirms it, yet such details are seldom reported in the literature."

But at least they all love to share with each other...right? 

Here, we were told, in the more marginal areas of the world were societies that were depicted as just the opposite of the industrial West, societies characterized by egalitarianism, widespread sharing of resources, an indifference to material possessions, societies whose members seemed to live in harmony with nature and one another and whose wants were modest and easily satisfied....sharing that goes on seems to be as much motivated by jealousy and envy as it is by any value of generosity or a "liberal custom of sharing." In his survey of foraging societies, Kelly (1995:164-65) notes that "Sharing... strains relations between people. Consequently, many foragers try to find ways to avoid its demands .... Students new to anthropology..,. are often disappointed to learn that these acts of sharing come no more naturally to hunter- gatherers than to members of industrial societies."...(1982:55) recounts the incident of an elder Bushman who asked him for a blanket. When Lee responded that he would just give it away, the elderly Bushman replied, "All my life I've been giving, giving; today I am old and want something for myself." Lee adds that the sentiments expressed by this elder were not unique. Perhaps "human nature" is not as different from society to society as we have been led to believe.

 

Perhaps there was a golden age, where fatty game was more abundant and sharing came easily. But the Bushman don't tell us much about that and overall it remainds a speculation. 

Suggestions that humans may have obtained more calories from SCFA in the past are rooted in estimates of fiber consumption from the Paleolithic. Evidence is rather sparse and limited to coprolites. In the burgeoning field of evolutionary medicine, anthropologists have become very interested in the Paleolithic diet and its relevance for promoting health today. Some of the landmark papers in the field have cited these coprolite studies as evidence for fiber intakes as high as 150 grams as day, well over what any known human culture currently consumes (M. Konner & S Boyd Eaton, 2010). Even if the method for estimating fiber consumption from coprolites is accurate, they may not support the conclusion that they represent some species level optimal and may in fact suggest a ceiling for safe fiber consumption that great apes do not share.

The argument for studying the Paleolithic diet in order to see what is optimal for modern humans to eat stems from the fact that archeological remains suggest that Paleolithic hunter-gatherers were healthier than their agrarian descendents (S B Eaton, M. J. Konner, & Shostak, 1996). Generally, they were taller, had fewer skeletal pathologies, and their teeth were in much better condition ¹. One of the sources for these high fiber estimates is coprolites from prehistoric Indians in the North American desert southwest, who consumed as much as 150 to 225 grams of fiber a day (Leach & Sobolik, 2010). Far from being in admirable health, evidence shows they had extensive dental caries. Some have speculated that this was caused by high levels of phytoliths in their diet, which wore down their teeth (Danielson & Reinhard, 1998). But other populations with extensive tooth wear do not exhibit high levels of caries² (B. H. Smith, 1984). This raises the question of whether or not wear really caused their caries or if perhaps their fiber consumption caused them.

Clues come from modern nutritional biochemistry. Dietary fiber has the ability to reduce blood levels of Vitamin D, which is vital in tooth and bone mineralization (Batchelor & Compston, 1983). This may be the reason that some populations with high-fiber diets in Asia exhibit vitamin D deficiency despite adequate sun exposure. Children on macrobiotic diets, which are high in fiber, have higher than normal rates of rickets (Dagnelie et al., 1990). However, macrobiotic diets and those of rural Asians are notably low in animal products and high in plants different from those our Paleolithic ancestors ate, which contain mineral-leaching phytic acid (Raboy, 2001). The fiber in other primate diets and presumably in Paleolithic diets is mostly dicot vegetable fiber, whereas modern grain fibers come from monocotyledonous plants (Milton, 1989). It’s also possible that these problems would not occur at Paleolithic levels of animal product consumption, as animal products are rich sources of vitamin D and minerals (M. Konner & S Boyd Eaton, 2010).

Other anthropologists have tried to infer ancestral fiber consumption based on the diets of modern foraging populations and agrarians, but these have run into their own problems. Incorrect laboratory methods of analysis marred early data sets, though some of these data sets are still being cited in newer papers. Some examples include an estimate for Ugandan fiber consumption of 150 grams a day that was revised to 70 grams a day and an estimate for Kenyans of 130 grams a day reduced to 86 grams a day (Wrangham, Conklin-Brittain, & C. C. Smith, 2002). Other problems have come from analyzing fiber outside of dietary context. For example, much like we don’t consume the peels of bananas, Hadza don’t consume whole wild tubers. When they eat tubers, they chew them and the excess fiber is spit out. Obviously estimates of fiber consumption based on the whole tuber are overestimates (Schoeninger, 2001).

Fiber spit out by the Hadza

Given this, the use of extremely high estimates for Paleolithic fiber intake based on limited data as a baseline for optimal consumption seems misplaced. No known culture consumes over 100 grams of fiber. The highest recent estimate was 86 grams for some agrarian cultures in Africa (Wrangham et al., 2002).

Some of the issue is also overemphasis on fiber, when other food constituents that play a similar role may have been more important in human evolution. Early optimism that high fiber could prevent many diseases of civilization like heart disease and type II diabetes spurred many studies on the matter. These have had mixed results. There have been several expensive failed studies such as the forty-nine thousand women Dietary Modification Trial of the Women’s Health Initiative which found that increasing dietary fiber had no effect on risk of colon cancer, breast cancer, or heart disease and no effect on weight loss (Beresford et al., 2006). Those who cling to the fiber hypothesis insist that the trials have not been long enough or high enough in fiber (Byers, 2000).

Focus on fiber in the past was on its abilities as indigestible bulking matter to increase digestive transit time and bind up certain food constituents. (J. Smith, Yokoyama, & German, 1998). The dominant theory was that slower transit time allowed carcinogens and other potential toxins to fester in the body. This idea that spawned a cottage industry of quacks and religious movements advertising “cleanses” (Kellogg, 1923) that has remained robust to this day , but has not stood up to scientific scrutiny.

Next up: fiber or bacteria??
 

1. This argument seems suspect, since while early agrarians seemed to have had high levels of disease based on skeletal evidence, later agrarians and pastoralists are often much taller than people in the Paleolithic and also exhibit low incidence of pathology.

2.  Including cultures that purposefully file down their teeth

Batchelor, A. J., & Compston, J. E. (1983). Reduced plasma half-life of radio-labelled 25-hydroxyvitamin D3 in subjects receiving a high-fibre diet. The British journal of nutrition, 49(2), 213-6. Retrieved May 2, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/6299329.

Beresford, S. a a, Johnson, K. C., Ritenbaugh, C., Lasser, N. L., Snetselaar, L. G., Black, H. R., et al. (2006). Low-fat dietary pattern and risk of colorectal cancer: the Womenʼs Health Initiative Randomized Controlled Dietary Modification Trial. JAMA : the journal of the American Medical Association, 295(6), 643-54. doi: 10.1001/jama.295.6.643.

Byers, T. (2000). Diet, colorectal adenomas, and colorectal cancer. The New England journal of medicine, 342(16), 1206-7. doi: 10.1056/NEJM200004203421609.
Dagnelie, P., Vergote, F., Staveren, W. van, Berg, H. van den, Dingjan, P., & Hautvast, J. (1990). High prevalence of rickets in infants on macrobiotic diets. Am J Clin Nutr, 51(2), 202-208. Retrieved May 2, 2011, from http://www.ajcn.org/cgi/content/abstract/51/2/202.

Danielson, D. R., & Reinhard, K. J. (1998). Human dental microwear caused by calcium oxalate phytoliths in prehistoric diet of the lower Pecos region, Texas. American journal of physical anthropology, 107(3), 297-304. doi: 10.1002/(SICI)1096-8644(199811)107:3<297::AID-AJPA6>3.0.CO;2-M.

Eaton, S B, Konner, M. J., & Shostak, M. (1996). An evolutionary perspective enhances understanding of human nutritional requirements. The Journal of nutrition, 126(6), 1732-40. Retrieved March 26, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/8648449.

Kellogg, D. J. H. (1923). Natural Diet of Man.

Konner, M., & Eaton, S Boyd. (2010). Paleolithic nutrition: twenty-five years later. Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition, 25(6), 594-602. doi: 10.1177/0884533610385702.

Leach, J. D., & Sobolik, K. D. (2010). High dietary intake of prebiotic inulin-type fructans in the prehistoric Chihuahuan Desert. British Journal of Nutrition, 103(11), 1558-1561. Retrieved May 10, 2011, from http://journals.cambridge.org/abstract_S0007114510000966.

Milton, K. (1989). Primate diets and gut morphology: implications for hominid evolution. In M. Harris & E. B. Ross (Eds.), Food and Evolution: Toward a Theory of Human Food Habits (p. 93). Temple University Press. Retrieved May 8, 2011, from http://books.google.com/books?hl=en&lr=&id=xHYxSHr86T8C&pgis=1.

Raboy, V. (2001). Seeds for a better future: “low phytate” grains help to overcome malnutrition and reduce pollution. Trends in plant science, 6(10), 458-62. Retrieved May 9, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/11590064.

Schoeninger, M. (2001). Composition of Tubers Used by Hadza Foragers of Tanzania. Journal of Food Composition and Analysis, 14(1), 15-25. doi: 10.1006/jfca.2000.0961.

Smith, B. H. (1984). Patterns of molar wear in hunger-gatherers and agriculturalists. American journal of physical anthropology, 63(1), 39-56. doi: 10.1002/ajpa.1330630107.

Smith, J., Yokoyama, W., & German, J. B. (1998). Butyric Acid from the Diet: Actions at the Level of Gene Expression. Critical Reviews in Food Science and Nutrition, 38(4), 259-297. doi: 10.1080/10408699891274200.

Wrangham, R., Conklin-Brittain, N.-L., & Smith, C. C. (2002). A Two-Stage Model of Increased Dietary Quality in Early Hominid Evolution: The Role of Fiber. In P. S. Ungar & M. F. Teaford (Eds.), Human diet: its origin and evolution (p. 206). Greenwood Publishing Group. Retrieved May 9, 2011, from http://books.google.com/books?hl=en&lr=&id=6GDELypdTUcC&pgis=1.
 

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