Caveman Doctor was recently eating some liver that he acquired in a hunt. Ok, he bought it from a local farmer whose cows roam the land eating grass, and he avoids the use of pesticides and antibiotics, but close enough. During the feast with his fellow caveman, Roger, they were discussing the diet of modern hunter-gatherers and were wondering if some quality data (whatever data is) existed for the societies, as it would be very insightful regarding which foods we can eat and perform well on a daily basis. Luckily, this data actually does exist.
The Foods that Sculpted Our Body to Avoid the Diseases of Civilization
Humans have been roaming the earth for roughly 2.5 million years. During this long period of time, our diet has likely changed significantly. Our diet was dependent on the time in history (cooling or warming periods), location (tropical vs. frigid vs. seasonal), season, and based on the food sources that were available at that time. While these factors vary throughout, one thing is certain: only a minute slice of this time involved a diet that included sugar or processed oils and even grains.
Enough about what we didn’t eat. What about the foods that we actually did eat the majority of the time and what foods are/were found in those societies that avoid diseases of civilization? Addressing this issue through an ancestral approach by examining modern and recent hunter gatherers gives us a glimpse into the past. Many anthropologists have dedicated their careers to such an endeavor, and we have them to thank for the plethora of data in which they have provided us.
One such group has looked at nine hunter-gatherer societies, providing a remarkable amount of dietary data on these groups.1 Looking at a moderate amount of macronutrient composition data of these hunter gatherer societies helps us to paint a picture as to what foods allow our body to function under high demands, avoid diseases, and are likely similar to those foods we have been eating for several million years. In other words, it shows us which foods help sculpt our body to function to the best of its ability. The table below (click to enlarge) charts the daily food intake of these modern hunter-gatherer groups.
The Diet of Modern Cavemen
Interestingly, meat and invertebrates, including snails, crabs, worms, and insects, on average compose well over half of the cumulative hunter gatherer diet at 65%, with five societies consuming 78% or above. While we don’t know exactly how much of this food is fat versus protein, the consumption of organ meats by these traditional people and the composition of most animals (most of the animal is consumed with the organ and fatty parts being the prized portions), it is safe to assume a large majority of this is fat. Other societies not discussed in this data prized the fatty portions of animals as well, including the Plains Indians, who made pemmican (a block of mostly fat with dried buffalo meat), and other tribes along the Pacific Coast who made boxed oolican grease. They clearly consumed large proportions of dietary fat, but exactly quantifying these amounts remains a daunting and nearly impossible task.
Of even more interest, from looking at the table above, only the !Kung and Gwi did not get the majority of their calories from animal sources. That being said, data on the !Kung is inconsistent, and while they may not have eaten as much meat as some of the other groups, some meat was replaced by seeds or nuts, which are mostly fat sources. They also ate plenty of the fatty mongongo fruit2, leaving their dietary composition of largely fat, much like the other groups.
Plant foods varied significantly, with roots (i.e. tubers like sweet potatoes) composing the majority of non-animal foods and fruit even lesser so (except for the Nukak – see below). Tubers may have been more protected from insects and animals, allowing them to be consumed more often or left in the ground as fallback food, a strategy frequently employed by the Hadza.3 Fruits must be consumed in an appropriate amount of time by humans, or they will lose out to animals and more often, insects. One advantage for humans is that they can then consume the animals that ate their fruit, therefore obtaining these nutrients secondhand.
In terms of carbohydrate consumption, most of these groups ingest under one-fourth of food intake as carbohydrates, with the Hadza, Gwi, and Nukak consuming more plant sources. However, the Nukak in Columbia consume a large amount of palm fruit.4 Even more than the mongongo, palm fruit is nearly all fat, and 50% saturated. Therefore, while a significant portion of their diet was fruit based, it remained consistent with most of the other diets with fat as the primary source of sustenance. As a result, the Gwi and Hadza were the only two hunter-gatherers to eat a relatively high amount of carbohydrates.
One group that was not analyzed was the Inuit (Eskimo) population in Northern Canada. During his time as the treating physician, J.A. Urquhart describes a diet of nearly 100% fat with small amounts of protein.5 An extreme example certainly, though it is rather interesting to note that during his seven years living among Inuit members of all ages with access to all the diagnostic equipment available at that time (including x-ray imaging and surgical evaluation), he had not seen a single case of cancer.
Important Factors to Consider from this Data:
- Exact macronutrient makeup varies between hunter-gatherer societies.
- None consume sugar, processed oils or grains, as these foods were not part of hunter-gatherer diets, or substantial in any diet from 10,000 years ago to the beginning of time.
- The clear overriding theme is that animal products (i.e. mostly fat and lesser so protein) make up the vast majority of food intake within these societies.
Hunter-Gatherer Food Pyramid
Contrast this with the USDA’s dietary guidelines, which recommend an increase in whole grains and processed oils (which play no part in the diets listed above), with a restriction in solid fats and saturated fat (the near vast majority above).6 These are absolutely not the foods with which our bodies were sculpted to process and play no part in the diets of those who have avoided diseases of civilization. When our bodies reject such modern franken foods, it is no surprise when they lead to obesity, diabetes, heart disease, and cancer. This also includes basing an entire diet on carbohydrate sources, which only one of these groups did.
Nutrient and Calorie Dense Foods: The Basis of Health
Regardless of which society we view, one dietary aspect persists – food consumption revolves around eating the most nutrient and calorie-dense foods. When one considers hunter-gatherer societies, where the goal is to acquire food in order to survive, it only follows that eating the foods with the highest concentrations of calories and nutrients would provide the largest benefit physiologically for the body and brain. From a cost/benefit function (energy spent acquiring food to energy derived from the food), it is irrational to dedicate large amounts of energy to acquire foods with little nutrient return on the investment. Unfortunately, this is the backbone of the US dietary paradigm.
Food for Our Gut:
However, this is not the only explanation as to why humans have consumed energy and nutrient-dense foods for the vast majority of their existence. Several explanations account for the vast amount of nutrient-dense foods that humans consumed, including meat and even some starches versus low-nutrient plants and fruit by comparison. As Kaplan’s group explains1, humans have consumed rarer and harder to acquire nutrient-dense foods while apes consumed their low-nutrient counterparts, which explains the difference between our gut anatomy, physiology, and brain size. More specifically, chimpanzees can rapidly absorb nutrients from foods that quickly pass through the gut, like fruit, while humans can meet the nutrient requirements more easily through the consumption of slower passing foods, like meat, and such differences may be represented by the vastly larger human small intestine, where most digestion occurs, versus the colon, which dominates in size in apes.7,8
In fact, over half of the length of the digestive tract in humans is made up of small intestine. Interestingly, while many carbohydrates go undigested, only to be handled by bacteria in the large intestine, fats are degraded and absorbed within the small intestine9,10, as are most of the nutrients present within our food.11 This alone may give humans the edge over apes by providing them with the ability to derive sustenance from nutrient-dense foods by using their much larger small intestines. Is it a coincidence that the human diet has involved heavy fat and animal sources over millions of years and the largest organ of our digestive tract is that which is meant to digest and absorb fats? The issue here is less whether the fat in the diet lead to the larger small intestine or whether it was there all along, but rather the fact that our bodies have been manufactured to process a majority of nutrient-dense fats within the diet. It is also no surprise that fat within the intestine is the regulator of appetite which stimulates signals, like the hormone Cholecystokinin (CCK), which tell the body that it know that it no longer needs to be hungry and should instead focus on digesting the nutrient and calorie-dense food within the small intestine.12 This is one reason why those consuming a low-fat diet have a steeper road ahead of them as they often experience hunger that is difficult to fight. Adding to the problem is the fluctuations of their insulin and blood sugar which cause further hunger. The cycle repeats when they turn to similar low-fat foods to quench their hunger.
Food for our Brain:
While our gut is designed to digest and absorb energy-dense fatty foods, it is no surprise that the fat absorbed by our gut is the major fuel for our brain (another factor separating man from ape), which is 60% lipid.13 In fact, human breast milk provides newborns with a 60% fat solution which is highly necessary for brain development and function.14 Finally, keep in mind that these hunter-gather cultures work together to hunt and acquire food.15 This executive functioning and cooperation are additional factors which we can attribute to brain function, thanks to fat consumption, which has increased human intelligence and allowed us to migrate to the top of the food chain.
Big Small Intestine = Big Fat Consumption = Big Brain
There are several reasons that our diets consisted primarily of animals and animal fat:
- Such energy and nutrient dense foods helped to fuel our brain
- Such foods are generally more difficult to acquire, which is why more intelligent humans are capable of acquiring them. Compare this with chimpanzees, which eat a small fraction of meat.16 You need a bigger brain to be able to catch a prey or dig up buried roots. Subsequently, those harder to hunt animals provide your brain with a rich source of fatty acids to function properly.
- Our bodies are meant to process these foods after 2.5 million years of consuming them and we have the machinery to digest and absorb such foods.
SAD: Standard American Diet:
Contrast this to the standard American diet, which consists of a much reduced 32% fat, 16% protein, and 49% carbohydrates.17 While these numbers dominate the amount of carbohydrates consumed by hunter-gatherers, our dietary recommendations suggest an even higher amount of carbohydrates and lower fat.6 These misguided recommendations also mention avoiding calorie-dense foods, which also happen to be nutrient-dense, as these recommendations follow the weight loss advice of “exercising more and eating less.” Massive increases in the rate of obesity have followed since employing this strategy.18
Mirroring modern day hunter-gatherer societies likely involves eating the same foods our ancestors consumed for millions of years. These high fat foods are the same sources of sustenance that our bodies are designed to process, and these foods likely help us to avoid the diseases of civilization, including diabetes, obesity, and even cancer. This does not mean to eliminate all fruit or vegetables, as we can clearly derive benefit from these foods, as modern hunter-gatherers do and we have done in the past. However, it is clearly efficient for our body, brains, and appetites (and therefore sanity) to consume the same energy and nutrient-dense foods that our intestines are designed to process and absorb, resulting in energy in which our brain is designed to use.
Once again, the pathway to health is deep rooted in our history, and Nature was kind enough to provide plenty of modern examples of what happens when we eat the foods we were meant to process.
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2. Belovsky GE: Hunter-Gatherer Foragirig: A Linear Programming Approach. Journal of Anthropological Archaeology 6:29-76http://deepblue.lib.umich.edu/bitstream/2027.42/26778/1/0000334.pdf
3. Marlowe FW, Berbesque JC: Tubers as fallback foods and their impact on Hadza hunter-gatherers. American journal of physical anthropology 140:751-8, 2009, http://www.ncbi.nlm.nih.gov/pubmed/19350623
4. Macía M, Armesilla P, Cámara-Leret R, et al: Palm Uses in Northwestern South America: A Quantitative Review. The Botanical Review 77:462-570, 2011, http://dx.doi.org/10.1007/s12229-011-9086-8
5. Urquhart JA: The most northerly practice in Canada. 1935. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne 147:1193-6, 1992, http://www.ncbi.nlm.nih.gov/pubmed/1393934
6. USDA: Dietary Guidelines for Americans.
7. Milton K: A hypothesis to explain the role of meat-eating in human evolution. Evolutionary Anthropology: Issues, News, and Reviews 8:11-21, 1999, http://dx.doi.org/10.1002/(SICI)1520-6505(1999)8:1<11::AID-EVAN6>3.0.CO;2-M
8. Milton K, Demment MW: Digestion and passage kinetics of chimpanzees fed high and low fiber diets and comparison with human data. The Journal of nutrition 118:1082-8, 1988, http://www.ncbi.nlm.nih.gov/pubmed/2843616
9. Hubscher G: Transport of lipid across the small intestine. The Biochemical journal 114:46P-47P, 1969, http://www.ncbi.nlm.nih.gov/pubmed/5343743
10. Spencer RP: Spatial Distribution of Intestinal Activities. The Yale journal of biology and medicine 36:279-94, 1964, http://www.ncbi.nlm.nih.gov/pubmed/14120286
11. Thomson A, Drozdowski L, Iordache C, et al: REVIEW: Small Bowel Review: Normal Physiology, Part 1. Digestive Diseases and Sciences 48:1546-1564, 2003, http://dx.doi.org/10.1023/A:1024719925058
12. Beglinger C, Degen L: Fat in the intestine as a regulator of appetite—role of CCK. Physiology & Behavior 83:617-621, 2004, http://www.sciencedirect.com/science/article/pii/S0031938404004160
13. Crawford MA: The Role of Dietary Fatty Acids in Biology: Their Place in the Evolution of the Human Brain. Nutrition Reviews 50:3-11, 1992, http://dx.doi.org/10.1111/j.1753-4887.1992.tb01283.x
14. Crawford MA, Hassam AG, Stevens PA: Essential fatty acid requirements in pregnancy and lactation with special reference to brain development. Progress in Lipid Research 20:31-40, 1981, http://www.sciencedirect.com/science/article/pii/0163782781900114
15. Henrich J: Social science: Hunter-gatherer cooperation. Nature 481:449-450, 2012, http://dx.doi.org/10.1038/481449a
16. Wrangham R, van Zinnicq Bergmann Riss E: Rates of predation on mammals by gombe chimpanzees, 1972–1975. Primates 31:157-170, 1990, http://dx.doi.org/10.1007/BF02380938
17. CDC: Trends in Intake of Energy and Macronutrients — United States, 1971–2000, 2004
18. Cite Centers for Disease Control and Prevention, The Obesity Epidemic. Available at: < http://www.cdc.gov/cdctv/ObesityEpidemic/>. Accessed July 27, 2011
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