I grew up on a farm in the rolling hills of piedmont Virginia. Among the earliest lessons I learned was that you had to give animals the appropriate food. The black angus cattle were fed one thing, the chickens another, the pigs something else. If animals didn’t get the right type of food, they simply weren’t healthy and didn’t grow and reproduce properly. Although I didn’t understand it at the time, we were feeding each type of animal an evolutionarily appropriate diet. This is also a basic concept for zookeepers—for animals to thrive in captivity they need to be fed the diet they evolved to eat, the one that matches the structure of their mouth and digestive system and that is appropriate for their particular physiology.
One of the basic tenets of the developing fields of Ancestral Health and Evolutionary Medicine is that humans are now living in a “novel” environment—a new environment very different from the one in which we evolved. For the vast majority of the past two million years our ancestors evolved as hunter-gatherers on the African savannah. The modern world is radically different from this ancestral home, the home that shaped our genetics. As a result, there is an evolutionary mismatch between the conditions under which we evolved and how we now live. The differences take many forms: we live in much more crowded conditions; we are subjected to very different types of stress; modern humans often live in much dirtier or sometimes much cleaner environments; we are exposed to a wide variety of pollutants, pesticides, preservatives, and other chemicals; and we have very different diets. But the bottom line is that the genes our species evolved don’t match the ways in which we now are living; we are genetically “out of synch” with the modern world.
Among the most important differences is diet. In only about 12,000 years humans have gone from living in small groups as hunter-gatherers eating wild animals and plants, to living in large, complex, agricultural societies typically eating a grain-based diet. Even more shocking, in only a little over 100 years we have gone from eating a diet based largely on unprocessed whole foods to the factory-produced, highly processed, “manufactured” diet of today.
People living only 100 years ago ate almost nothing from a box, bag, or can; their food had virtually no artificial additives, preservatives, or pesticides; it often contained large amounts of animal fat (lard, tallow, bacon fat, etc.) instead of processed vegetable oils; and it was relatively low in sugar (since sugar was expensive).
Evolution is a slow process and cultural change, including our diet, has simply outpaced the ability of natural selection to keep up. It should thus not be surprising that many of the adaptations that were advantageous to us as hunter-gatherers might be disadvantageous under very different modern conditions. In other words, many of our characteristics are anachronisms that evolved under different circumstances and are not appropriate under the current novel conditions.
It would be surprising if there were not consequences of being mismatched with our evolutionary past. One of the consequences is that we now face shocking rates of many health problems, the “Diseases of Civilization,” including diabetes, obesity, cancer, heart disease, and hypertension. This is in stark contrast to the low rates of such problems in hunter-gatherers despite of the fact that some individuals lived vigorous lives into their 50s, 60s, 70s, or even beyond without access to modern medical care. In future posts I’ll look at some of the causes of these different health outcomes and examine solutions that are being successfully applied by many people in the modern world.