“Whenever and wherever it was ecologically possible, hunter-gatherers would have consumed high amounts (45–65% of total energy) of animal food. Most (73%) hunter-gatherer societies worldwide derived >50% (≥56–65%) of their subsistence from animal foods, whereas only 13.5% of these societies derived more than half (≥56–65%) of their subsistence from gathered plant foods. In turn, this high reliance on animal-based foods coupled with the relatively low carbohydrate content of wild plant foods produces universally characteristic macronutrient consumption ratios in which protein intakes are greater at the expense of carbohydrate.”[Italics added.]
In Part 2.0, I outlined the three main propositions Cordain et al attempted to support:
1. Hunter-gatherers would have eaten more animal than plant food “wherever and whenever possible;”
2. Wild plant foods have a “relatively low carbohydrate content;” and
3. The paucity of plant foods available to hunter-gatherers made it necessary for them to focus their hunting on procuring large game supplying large amounts of fat.
In Part 2.0, I showed that anthropologist Katherine Milton provided a number of reasons to doubt that the database used by Cordain et al (Murdock’s Ethnographic Atlas) provides a solid foundation for support of the first of these three propositions. Now I would like to take a closer look at the other two.
So, I think that we have three questions to explore:
1. Did wild plant foods really have a “relatively low carbohydrate content” compared to cultivated (agricultural) foods?
2. Did any or many hunter-gatherer groups have access to significant quantities of wild plant foods?
3. Did hunter-gatherers universally spurn plant foods in favor of animal foods, or did any highly value plant foods even more than animal foods?
Carbohydrate Content of Wild Plant Foods
In the Plant-Animal Ratios paper, Cordain et al wrote:
“We used the average plant macronutrient values of 62% of energy from carbohydrate, 24% from fat, and 14% from protein based on the previously analyzed database of 829 wild plant foods (17). Because of the similarity (3.5% difference) in the mean energy density of wild plant (6.99 kJ/g) and animal foods (7.24 kJ/g) in our database, we assumed that the P-A subsistence ratio based on weight in the Ethnographic Atlas would be virtually identical to the P-A subsistence ratios based on energy.”
Now, as quoted above, Cordain et al described wild plant foods as “relatively low in carbohydrate.” Whenever someone says “relatively” s/he means relative to something else. I will assume that Cordain et al meant that wild foods are low in carbohydrate relative to cultivated foods, not to processed foods, because they are making an argument in favor of mimicking a wild rather than agricultural diet.
So, do wild plant foods supply less carbohydrate than cultivated plant foods? Let’s see.
Two factors influence the carbohydrate delivery of a food: it’s energy density, and the proportion of energy delivered as carbohydrate.
Cordain et al describe their (mythical) average wild plant food as providing 62 percent of energy from carbohydrate and 6.99 kJ/g (1.7 kcal/g). Does this profile make wild plant food significantly “lower in carbohydrate” than common staple plant foods of agricultural people?
I used the USDA database to find the energy density and carbohydrate content of four higher-carbohydrate and one lower-carbohydrate cultivars, at least three of which have served as the staple food for at least one agricultural tribe: sweet potatoes, white potatoes, boiled brown rice, boiled lentils, and almonds.
I found the following: Sweet potatoes supply 0.9 kcal/g and 80 percent of energy as carbohydrate, baked white potatoes supply 0.9 kcal/g and 82 percent of energy as carbohydrate, boiled brown rice supplies 1.1 kcal/g (4.7 kJ/g) and 79 percent as carbohydrate, boiled lentils supply 1.2 kcal/g (4.9 kJ/g) and 41 percent of energy from carbohydrate, and almonds supply 5.6 kcal/g (24.1 kJ/g) and 6 percent of energy as carbohydrate. In tabular form, including the average wild plant food figures from Cordain:
Thus, the “average plant macronutrient value” used by Cordain et al indicates that the mythical average plant food used by hunter-gatherers had an energy-density almost double that of sweet potatoes or white potatoes and 50 percent greater than boiled lentils. Thus, the "average wild plant food" doesn't appear particularly low in energy (kcalories) compared to any of these cultivated foods except for the low carbohydrate almonds.
As for carbohydrate, the “average wild plant food” delivers 50 percent more carbohydrate as a proportion of energy than lentils, and ten times more carbohydrate (as a percent of energy) than almonds. (I know, Cordain et al created an average...I'll get to that soon.)
Let’s compare Cordain et al’s “average wild plant food” with white potatoes. A 100 g serving of white potatoes would supply 90 kcal and 74 kcal as carbohydrate, or 18 g carbohydrate. A 100 g serving of the “average wild plant food” would supply 170 kcal and 105 kcal as carbohydrate, or 26 g carbohydrate.
So 100 g of the (mythical) “average wild plant food” supplies 40% more carbohydrate than white potato. Rather than being “relatively low in carbohydrate” compared to potato, the “average wild plant food turns out to relatively high in carbohydrate per 100 g serving.
Of course, the “average wild plant food macronutrient value” is derived by averaging the values of 829 wild fruits, seeds, nuts, underground storage organs (tubers, roots, etc.), leaves, dried fruit, flowers, gums, and miscellaneous plant parts. Averaging low-carbohydrate, high-energy-density plant values such as from nuts with high-carbohydrate, lower-energy-density plant values such as from tubers, and very low energy density foods like flowers will tend to bring down the “average” carbohydrate content and raise the average energy density. The same applies to cultivars.
If I average together the values above for those five cultivated plant foods, I get a mythical “average cultivated food” that supplies 1.9 kcal/g and 58 percent of energy as carbohydrate, not significantly different from the “average wild plant macronutrient value” used by Cordain et al. See table below.
In other words, the "average wild plant food" doesn’t appear exceptionally low in carbohydrate or energy compared to the average of these cultivated plant foods. One more calculation for fun:
Cordain et al's "average wild plant food" has an energy and carbohydrate density not significantly different from the average for these five cultivars.
I very much doubt that we would get significantly different results by including 829 cultivars, because we will get a mix of fruits (high-carbohydrate, low energy density), vegetables (generally moderate to high carbohydrate, low energy density), grains (moderately high in carbohydrate, energy density similar to brown rice), legumes (low to moderate carbohydrate, energy density similar to lentils), seeds and nuts (low carbohydrate, high energy density). Edible plants simply have consistent energy density and carbohydrate ratios whether wild or cultivated. It seems mythical that wild plant foods differ markedly from cultivars in energy density or carbohydrate content.
Plants Used By Hunters
Cordain et al imply that nature provides relatively small quantities of carbohydrate-rich plant foods, making pursuit of animal fat the route to optimal foraging. In her editorial comments on the Plant-Animal Ratios paper, titled Hunter-Gatherer Diets—A Different Perspective, Milton disagreed, pointing to a number of examples where hunter-gatherers clearly have relied on plant foods as the basis of their diets. From her editorial:
“In the average collecting area of an Aka Pygmy group in the African rain forest, the permanent wild tuber biomass is 4545 kg (5 tons) (19).
"Australian aborigines in some locales are known to have relied seasonally on seeds of native millet (2) or a few wild fruit and seed species (20) to satisfy daily energy demands. Some hunter-gatherer societies in Papua New Guinea relied heavily on starch from wild sago palms as an important source of energy (21), whereas most hunter-gatherer societies in California depended heavily on acorn foods from wild oaks (22).”
So, starchy plants aren't necessarily scarce in hunter-gatherer environments. Assuming that the wild tubers available to the Pygmies have an energy density of ~1.0 kcal/g, the permanent wild tuber biomass in their forest gives them continuous access to 4, 545, 000 kcal, constantly regenerated by photosynthesis. In addition to this, consider the findings of Melissa Darby, described in my book:
“Anthropologist Melissa Darby, M.A., of Lower Columbia Research and Archaeology (Oregon) says that a woman gathering carbohydrate-rich camas could net 5,279 calories per hour. …..In 1996 Darby demonstrated that hunter-gatherers in the Northern Hemisphere had access to Sagittaria latifolia, a prolific wetlands plant that produces a tuber very similar to the white potato, which the Chinook Indians called wapatos. This plant grows in Europe as well as North America, the tuber is easy to harvest, and abundant from late fall through spring, when other high-carbohydrate plant foods may be scarce. Darby has harvested approximately 5,418 calories per hour gathering wapatos from a knee-deep pond. The tubers do not need grinding or mashing to be palatable, and can be cooked fresh, stored fresh in a cool place, or dried. They are thoroughly cooked in a bed of hot ashes in 10 minutes, and do not need stones for long oven cooking. Pollen data indicates the wapato was prolific in the last Ice Age through North America, the North American Great Basin, Siberia, and Northern Europe.(17)”
Five thousand calories per hour seems pretty productive--enough to feed two people for one day gathered in just 60 minutes. Darby claims that it is possible to harvest up to 10, 000 calories of wapato per hour in some seasons. If so, five hours of foraging would support a family of five people for several days assuming no other food source. Considering the low hazard and energy investment involved in harvesting wapatos, this seems like some optimal foraging to me. Anyway, back to Milton:
“These and similar data indicate that hunter-gatherer societies typically did not rely on many wild plant species specifically for energy. Rather, they had one or a few dependable wild staples (some also good sources of protein) that provided much of their energy needs. In nature, any dependable source of digestible energy is generally rare and when discovered is likely to assume great importance in the diet. Animal foods typically are hard to capture but food such as tree fruits and grass seeds are relatively reliable, predictable dietary elements. …Humans are quick to appreciate the value of reliable energy-providing staples and will work hard to ensure a steady supply of them.….. Contemporary ethnographers working in Amazonia noted that even when smoke racks are filled with game, if the carbohydrate staple becomes exhausted, the inhabitants say they have no food (23).” [Italics added.]
So some hunters of wild game apparently considered their starchy staple “food” and their game not food per se. This sounds similar to the situation in agricultural societies. In English, we call a main eating event a “meal” which is the word for a starchy food, namely ground grain, e.g. cornmeal or oatmeal. In China, the word for rice or cereals (‘fan’) is also used as the word for food in general, while vegetables, fruits, and animal items are called ‘tsai,’ or "dishes."
Why would any animal so consistently across cultures consider some starchy plant the main food, and other plants only side dishes? Could it have something to do with how well whole food starches satisfy human hunger and nutritional requirements? A question to explore later.
And from her letter in reply to Cordain et al:
“Examination of the literature suggests that hunter-gatherers throughout the world took full advantage of any dependable sources of dietary energy in their environment (9–11), even devising complex technologies to secure energy from potentially toxic plant sources such as acorns and cycads (10, 11). Such dependable plant foods, in turn, tended to be relied on heavily for dietary energy. For this reason, Cordain et al's comments on the "low carbohydrate content of wild plant foods" seem largely beside the point—what is key is the steady availability of energy from 1 or 2 reliable wild-plant staples. To secure a dependable source of dietary carbohydrate, some hunter-gatherers, such as the Mbuti (Africa) and the Maku (South America), established symbiotic trade relationships with indigenous agriculturalists (12).”
So, it seems we have considerable evidence that at least some hunter-gatherers developed technology for accessing starchy foods, and some went out of their way to secure steady supplies of high carbohydrate starchy staple foods, apparently unattached to remaining "hunter-gatherers" or "paleo." So, a question to contemplate: If a hunter-gatherer does not cultivate foods himself, but trades some hunted or gathered wild foods for some cultivated foods, and eats the latter, does he remain a hunter-gatherer, or is he now an agriculturalist?
Milton believes that modern human neural and digestive physiology clearly suggest that human evolutionary diets probably included plenty of plant foods including high carbohydrate starchy staples. I also have some things to say about this. I will leave that discussion for Part 2.2.