Loren Cordain's Research
229 Hunter-Gatherer Populations
"Our study, in which we analyzed 229 hunter-gathering populations, showed that there was not one among these ethnic groups that would choose a vegetarian diet. In fact, where and when animal foods are available, these natural peoples always choose to eat those. There was a strong nutritional preference for animal nutrition in the 229 population groups we have examined."
"Most of the population (73%) included more than 46% of their daily intake in the form of animal food. The predominance of animal foods is explained by the fact that with the same energy input, more energy output can be obtained from animal food, than plants, as demonstrated by the optimum nutrition theory."
The preference and appetite of man for meat, poultry and other animal food has a long evolutionary history. In Africa, 2.5 million years of fossilized animal parts were found with the traces of stone tools used for processing. Such evidence leaves little doubt as to the fact that all human species have eaten animal foods from the beginning. We are carnivores rather than omnivores.
Researchers are able to determine the ratio of animal and plant nutrition for extinct human (hominoid) species based on the isotopes of fossilized bones. Each of our groups, examined so far, shows up to 2.5 million years ago a typical isotope image of a meat-based diet. Further, we can compare our biochemical and anatomical characteristics to the cat, which is completely predatory, with the same biochemical pathways that characterize animals consuming lots of meat.
Cordain's Concept of the Paleo Diet
The Paleo diet advises eating only foods available to Paleolithic humans. Because our genes change very slowly, it's assumed that humans are still best adapted to the diet that was forced on pre-human species and early humans by a series of ice ages. Habitat protected by caves and close to the sea, ensured warmth and a constant food supply. If land animals or birds could be hunted that was a bonus.
In the original description of the Paleo diet in Cordain's 2002 book, he advocated eating as much like Paleolithic people as possible, which meant:
55% of daily calories from seafood and lean meat, evenly divided
15% of daily calories from each of fruits, vegetables, and nuts and seeds
there was no dairy, almost no grains (which Cordain described as "starvation food" for Paleolithic people), no added salt, no added sugar
The Paleo diet is based on avoiding modern processed foods and dairy foods.
Michael R. Eades and Mary Dan Eades in their book Protein Power, explain it this way.
The base of the diet is grass-fed meat and wild game, including all the organs and the fat. Seafood if available.
Fibrous non-starchy vegetables, as desired and if available.
Moderate servings of nuts or seeds. Fruit and berries in small servings only in season.
New Paleo Diet "Innovations"
There is wide variability in the way this is interpreted and an ongoing debate over the specific foods eaten by our ancestors. For the satisfaction of many Americans, vegetables have become significant in the way the diet is usually described.
In her book "Primal Body, Primal Mind" Nora R Gedgaudas writes that "no known primitive culture in the history of the human species has ever adopted vegetarianism by choice."
US Vegetarian Influence
In the hands of many bloggers and people who publish recipes under the "Paleo" flag, there has been a strong shift towards a vegetarian diet with some meat and fish. That might make marketing sense, but it means that when we talk about Paleo, it becomes less and less clear what we are talking about.
Hungarian writer Gábor Szendi, writes about the "bizarre botanical's on the market, and the recipes infected with Paleo," but prepared by people who "do not understand the source of Paleo science." Gábor Szendi talks about the "mad Paleo movement."
In the same way to talk about low-fat Paleo, is to completely misunderstand the essence of this primitive dietary pattern.
Other Contributions Based on Science
In 1930 McClellan and Du Bois, from the Mayo Clinic, published a paper describing the meat and fat based diet they were using for the treatment of epilepsy. Without input from anthropology, this diet still represents quite well what Walter L. Voegtlin and Loren Cordain were later to describe. Voegtlin completely excludes raw vegetables.
Anthropologist and explorer Vilhjalmur Steffansson, added greatly to our knowledge of the Inuit who in the early 1900's lived on seal meat and fish alone, for most of every year. He went to great lengths to try and convince the US Army and medical doctors and the general public about this. Steffansson was convinced the when fed only on animal fat, meat and the offal from those animals the human diet was full and very healthy.
Staffan Lindeberg, in the 1990's studied the nutrition and health of the people on Kitava Island in the Pacific. From that study he developed some conclusions about Paleolithic diets.
In Hungry, in 2009, Gábor Szendi wrote a book not available in English. The title translates to "Paleolithic Nutrition." I've only read about 10 pages from his blog. He seems to be strongly committed to good science, but he also recognises that you also need to be a realist. It's not possible to reconstruct the dietary conditions of the past. There are social reasons for allowing some tolerance because in our society protein is expensive. He says that it's not original sin, to accept a meal prepared by contains legumes, or cheese or bread-crumbs. You need to make compromises. It's possible that the chef cooked the chicken in vegetable oil, but don't make a fuss about that, you can eat a more pure form of Paleo tomorrow.
The same year in the USA, Nora T Gedgaudas published "Primal Body, Primal Mind." I now have a copy of this book but I have not read it. It's a well designed book, with a large index, and several pages of references to Paleo resources. From what I can tell this is a well founded book, with sensible advice.