A Stone-Age Solution for a Modern Health Crisis

Category : Lifestyle Disease Connection
Author : Dr. Namita Tyagi

                    A Stone-Age Solution for a Modern Health Crisis

Disclaimer: This blog is for informational purposes only and should not be construed as medical advice. The reader should consult their health care provider before self diagnosing or altering their treatment based on anything they read here.

It is clear that our environment and in particular, our diet has a profound impact on our health. The human genome has been shaped by the environment of our ancestors. Evolutionary adaptations to environmental change occur in the form of spontaneous genetic mutations which, if beneficial, are more likely to be passed on to subsequent generations. This process is extremely slow with, on average, 1-2 mutations occurring per gene every million years. So it is fair to say that in terms of our biochemistry, humans are essentially stone age beings living in an environment which has been transformed by our own agricultural, industrial and technological progress.

Our primitive, hunter-gatherer ancestors of the old stone age [a period which began roughly 2.5 million years ago] and their more recent neolithic counterparts (a period known as the new stone age from 12,000 years ago to present times) lived relatively brief lives. If they survived the perils of childhood, they would most likely perish before the age of 40 from trauma, predation or infectious disease. In the case of women. childbirth was a major risk for early mortality. The discovery / implementation of antibiotics, vaccines, improved sanitation and better perinatal care in the past century have significantly reduced mortality in early life, thereby increasing the average lifespan of humans by a few decades.

It is interesting that the maximum lifespan attainable by humans, as a species, has changed surprisingly little during our evolutionary timeline. Potential reasons for this and a review of on-going research on likely methods of prolonging human lifespan will be discussed in future blog posts.

Today, modern humans are more likely to die of chronic, non infectious ailments such as atherosclerosis affecting the blood vessels of the heart and brain, several different types of cancers, type II diabetes and it’s complications as well as the neurodegeneration seen in diseases like Alzheimer’s and Parkinson’s. All these conditions run an insidious course, over several years / decades, thereby impacting the quality of life of the afflicted individuals and placing  a tremendous burden on the health care systems world-wide. They are all facilitated by common environmental, lifestyle and nutritional factors and are often collectively referred to as the diseases of aging, as the age of the patient is an important risk factor.

Recently, there have been remarkable gains in our understanding of the origins of many such diseases. It appears that they might all share a common root cause i.e. chronic, systemic inflammation, which along with environmental toxins and a sedentary lifestyle, is most likely the result of the inappropriate diet of modern humans compared to their pre-agricultural ancestors. This is analogous to the problems one might encounter if petrol is used as fuel in an automobile with a diesel engine or vice versa.

Since the advent of the agricultural revolution some 10,000 years ago  a mismatch has developed between the dietary needs of our bodies and a largely refined, grain based diet which, whilst being high in energy, is significantly less nutrient dense than the diet of our stone age ancestors. In fact there is powerful archaeological evidence in support of the pre-agricultural diet having been more suited to the metabolic and nutritional needs of us humans. For instance, the fossilized remains of  our stone age, hunter gatherer ancestors suggest that they were, on average, about 6 inches taller than their neolithic counterparts whilst also possessing better body compositions as well as stronger bones and teeth.

Our hunter-gatherer ancestors ate unprocessed animals and plants and their diets varied with the ecology of the area and the seasons. Studies on the carbon and nitrogen isotope composition of fossilized remains going back 2.5 million years show that they were mostly top level carnivores, deriving two thirds of their nutrients from animal sources. The remaining one third were derived from a huge variety of plants principally leaves, tubers, nuts and berries. They ate very little grain (the seeds of grasses) which might have been eaten only in times of starvation and famine. This was probably because grains were small, difficult to harvest and minimally digestible, without grinding to break-down cell walls and cooking to gelatinize starch granules.

This reliance on nutrient dense animal protein was directly responsible for the rapid expansion of our ancestor’s brains. The early hominin species from about 7 million years ago had relatively small brains (approximately 300 ml) similar to the brains of the great apes, with whom we share common ancestors. The size of the hominin brains increased over the ensuing millions of years until our species, the Homo sapiens, evolving some 300,000 years ago with brains which were roughly 5 times larger (1500 ml).

The Expensive Tissue Hypothesis which was formulated in 1995, proposed that a large human brain evolved at the expense of a much smaller gut, when compared to the apes such as chimpanzees and gorillas. In terms of its energy requirements the human brain is an expensive tissue occupying less than 2% of the body by mass whilst utilizing almost 25% of the body’s total energy intake. It is believed that to compensate for their larger brains, humans have evolved a relatively short gut (another energy hungry tissue) which is more suited to eating smaller volumes of nutrient dense foods and is inefficient at fermenting plant fibre due to the colon being markedly shorter when compared to other, largely herbivorous apes. Furthermore, it is clear that our acidic stomachs are more suited for breaking down high protein foods. Eating foods high in plant fibre would likely impair the absorption of essential nutrients such as vitamin B12 by raising the pH of the stomach secretions.

In the neolithic era, as humans began to cultivate grains and domesticate animals they were able to settle down and form civilizations. During this time our diets changed from being largely animal based to being heavily grain dependent. There is abundant evidence that grains can be deficient in several micro-nutrients necessary for human health whilst also containing anti-nutrients which further impair micronutrient absorption. Since our tools for processing grain were for the most part fairly crude in the pre industrialized era, the full effect of a nutrient deficient diet did not become evident until more recently. Refined sugars and carbohydrates were introduced into human diet a couple of centuries ago. In addition, in the last few decades refined seed oils, high in the pro-inflammatory, omega 6 fatty acids have also become an integral part of our diet. The inclusion of these foods has been at the expense of more nutrient dense, animal based foods.

It would appear that it is this overconsumption of a high glycaemic diet, with its insulin promoting effect combined with a diet deficient in essential nutrients (such as zinc, iron, iodine, potassium, taurine, vitamins B6 + B12 and the long chain, polyunsaturated, omega 3 fatty acids) which has resulted in an unhealthy internal milieu triggering the many chronic diseases mentioned above. 

In conclusion, since the evolutionary genetics of our physiology holds the explanations for most modern human diseases and physical frailties, it is fair to assume that it also provides solutions. In other words, eating a diet closer to that of our pre-agricultural, pre-industrial ancestors may return our bodies to a healthier state with a consequent prolongation of healthspan (the length of time in an individual’s life when one’s in reasonably good health) and perhaps even have a beneficial effect on our lifespan, by delaying the onset of age-related diseases.