The human diet has changed tremendously over the past 10.000 years. One of the main things that separate modern human diets from preagricultural ones is that the former contain many foods that differ markedly in their nutritional composition from those that were a part of the latter. This is not only true if we compare foods that were not a part of preagricultural human diets, such as butter and cheese, with those that were a part of preagricultural human diets, but it also to some extent extends to comparisons made between similar types of foodstuffs.
There’s no doubt in my mind that these discrepancies, which in my opinion don’t get enough attention within the evolutionary health community, nor the health/fitness community as whole, lie at the root of the many diet-related diseases that are currently sweeping the globe. There’s also no doubt in my mind that one of the main reasons why Paleolithic-type diets are so therapeutic is that they exclude “modern foods” that have, from an evolutionary perspective, an abnormal nutrient composition.
How “modern foods” differ from the ones that preagricultural humans ate
The foods that we human eat can be categorized based on their nutritional composition. Nature, including its many plants and animals, is built up according to a system. By understanding this system, we can make sense of nutrition and health.
The original human diet can be used as a reference point for assessing the healthfulness and nutritional value of different foods. When compared against this reference point, one of the most apparent abnormalities of contemporary human diets is that they contain many foods that have a supranormal concentration of fat, carbohydrate, and/or protein.
Butter, coconut oil, lard, vegetable oils, and several other foods that are a part of the diet of many contemporary humans contain extremely high concentrations of fat: concentrations that far exceed that of any of the foods that Paleolithic humans ate. As for carbohydrate, grains and processed foods rich in refined sugars are markedly higher in carbohydrate than fruits and vegetables, which were the primary carbohydrate-containing foods in preagricultural human diets. Even the content of protein has been elevated to supranormal levels in some modern food products, such as whey protein powders, which contain much higher levels of protein than meat and fish.
These differences are not small. For example, whereas the vast majority of Paleo foods don’t contain more than 23% non-fibrous carbohydrate by mass (1), some of the foods that are a part of contemporary human diets contain as much as 70-80 grams of carbohydrate per 100 gram (!!). That’s a pretty big difference.
Not only that, but many “modern foods” contain high concentrations of both carbohydrate and fat. This combination is not found in any Paleo foods. The foods that our primal forebears ate contained primarily carbohydrate or fat; none were high in both of these two macronutrients. Processed, modern foods such as pizza and potato chips are unique in that regard.
Grains, dairy products, and processed foods, all of which are evolutionarily novel additions to the human diet, are clearly in a very different category than the foods our Paleolithic ancestors ate with respect to their nutritional composition. What’s important to remember though, is that even the Paleo friendly foods that line the shelves of the modern supermarket differ somewhat from the foods that Paleolithic humans actually ate. This is largely because we humans have artificially selected plants and animals that have characteristics we like, and because the foods that the modern man eats is produced in a very different fashion than the foods that ancient humans ate. The fatty acid profile of domesticated meat differs from that of game meat (2), and there is often a marked difference between wild and domesticated fruits and vegetables with respect to their sugar and fiber content (3, 4).
Finally, it’s important to point out that it’s not just the total quantity of the different macronutrients that differs between “ancient” and “modern foods”; the types of proteins, fats, and carbohydrates also differ, as well as the content of many micronutrients. A general pattern is that our preagricultural ancestors ate foods that were more nutritionally dense than we do and that supermarket food is lower in fiber and omega-3 and higher in saturated fat, sugar, and starch than wild foods.
Nutritional discrepancies between the original human diet and contemporary diets underlie many modern illnesses
There’s no doubt in my mind that many of the aforementioned nutritional differences between the original human diet and contemporary human diets underlie many modern, diet-related diseases. We’re not eating the types of foods we evolved to eat. None of the systems that make up our bodies are designed to cope with a regular influx of wheat, butter, doughnuts, and other “modern foods”. Rather, they evolved in the presence of wild meat, fruits, nuts, tubers, and roots.
The infusion of large quantities of grains, dairy products, and processed foods into the human diet has made us fat, metabolically deranged, and sick (5, 6, 7, 8, 9). This is not surprising to an evolutionary nutritionist such as myself, seeing as these foods differ markedly in their nutritional composition from the foods that were available in human environments of the past.
This is something a lot of Paleo critics don’t understand. They largely overlook these differences and fail to acknowledge that there exists a system that brings order to the chaotic discipline that is nutritional science.
Unless we head into the wild and set out to gather for food and hunt animals, we’ll not be able to eat wild foods that are identical to those hunter-gatherers eat. That’s not something most people are prepared to do, which is completely fine. You don’t have to forage in the wild to eat healthy; making good choices at the supermarket goes a long way. Domesticated fruits, vegetables, and meats differ somewhat from their wild counterparts; however, these differences are small compared to the differences that exist between non-Paleo foods and Paleo-foods, regardless of whether they are domesticated or wild.
There are several steps we can take to ensure that our diet matches well with our evolved biology. The first one is of course to steer clear of modern foods such as doughnuts, white bread, and milk, or at least limit our consumption of these foods. The second is to buy and eat the highest quality food we can find and afford. Grass-fed or wild meats and organic or wild plant foods tend to be superior to their conventionally produced counterparts with respects to their nutritional profile. The third step we can take is to align the macronutrient composition of our diet with that of the ancestral diets that supported the evolution of the complex human body and brain. A ratio of 20-40% carbohydrate, 20-30% protein, and 30-60% fat is fitting for most people.