Studies unanimously show that hunter-gatherers and non-westernized people eating traditional diets are virtually free from “non-communicable” chronic disease (1,2,3,4,5,6).
While the average lifespan of humans today is higher than in any other part of human evolution, it’s clear that several factors such as decline in infant mortality, lower rates of infectious disease, and pharmaceutical use must be considered when comparing life expectancy (7).
Although our enivornment has changed dramatically since the paleolithic era, our genetic material (human) is largely the same as our ancestors’. There have been some minor adaptations, but we clearly haven’t adapted to the western diet and lifestyle. This gene-environment mismatch is the fundamental cause of the so-called diseases of cvilization (4).
Although there are lifestyle differences between the various hunter-gatherer societies and traditional people who’ve lived and still live around the world, there are also some common factors that explain why these cultures are so healthy and why we are seeing such a rapid increase in cardiovascular disease, cancer, metabolic syndrome, obesity, heart disease, and other chronic disorders in the modern world.
A diet that consists of ‘natural’, nutrient-rich whole foods is associated with good health. While the paleolithic man ate primarily seafood, meat, eggs, vegetables, fruit, fungi, roots, and nuts, traditional people living after the paleolthic era (10000 years ago–>) have also maintained good health with grass-fed, full-fat dairy products and traditionally prepared grains and legumes in their diets (8,9).
Although the macronutrient ratio of the diet could influence health, bodyweight, and longevity, studies show that humans have thrived on both high-carbohydrate (10,11,12,13,14,15), and high-fat diets (16,17). Rather than the macronutrient ratio of the diet, it seems that the shift from eating ‘natural’ food to eating processed food is especially important in regards to human health.
Hunter-gatherers and healthy traditional people lived in close contact with mother nature and were exposed to both “good” and “bad” microorganisms from food, soil/dirt, water, and the rest of the environment. Some hunter-gatherers such as the Hadza even eat the stomach and intestines of some of the animals they capture (18). Limitied exposure to soil microbes and other germs has been linked to increased risk of developing autoimmune disease and allergies. Humans have co-evolved with certain microorganisms, and this microbial exposure regulates our immune system and is essential for the development of a diverse and resilient microbiome (19,20).
Even though physical activity patterns vary between healthy traditional societies, estimates suggest that we are less active today than in any other part of human evolution (21). Regular physical activity is associated with many health benefits and seems to be important in the prevention of several chronic diseases (22).
Although the use of pharmaceuticals and vaccines has helped the human race overcome several infectious diseases and treat life-threathening disorders, there are also significant downsides with the increased use of most of these drugs. Of the drugs that are commonly used, oral antibiotics seem to be especially problematic since they disrupt the gut microbiome and decrease protection against infection from bacterial pathogens (23,24).
Other factors such as sleep, stress, sun exposure, and time outdoors also play an important role in the apparant mismatch between our ancient physiology and the modern diet and lifestyle.
The disconnect from our natural ecological niche is the primary reason why we’re seeing such a rapid increase in prevalence of chronic health disorders in affluent- and westernized nations.
One of the most important implications of this mismatch is the changes we see in the human microbiome.