Agriculture have been hailed as one of the greatest achievements of mankind. But recent evidence speaks otherwise. Turns out that the great Agricultural Revolution was the culprit behind civilization diseases.
Many scholars are of the opinion that agriculture have been the gravest mistake humans ever committed in the course of their evolution. Eminent writer and historian, Yuval Noah Harari, even goes to the extent of calling agriculture the biggest fraud in all of human history.
“The Agricultural Revolution was history’s biggest fraud.”
Yuval Noah Harari in ‘Sapiens: A Brief History of Humankind’
All of them are right somewhere down the course.
When we backtrack on the evolutionary path we followed to unearth the causes behind disorders like obesity, type 2 diabetes, cardiac problems, allergies, food intolerances, depression, dementia, some types of cancer and autoimmunity that have taken the form of epidemics, we land on agriculture. There is no beyond – agriculture is the culprit. It all started with agriculture. Our bodies could not cope up with the pace with which agriculture accelerated our climb up the Tree of Life. We are still adapted to the hunter-gatherer diet our ancestors were so familiar with for millions of years until agriculture happened. Agriculture narrowed down the range of food items our ancestors consumed on a daily basis – variety was lost. It brought about an imbalance in what our bodies required and what it obtained through its daily dietary intake. Carbohydrate based diets increased our calorie intake and in recent times with the advent of modernization a sedentary lifestyle emerged which further aggravated the problems.
Chronic non-communicable diseases (CNCDs) or civilization diseases, as we call it, are the cumulative result of the agricultural revolution and industrial revolution. In the bid to make lives comfortable modernization has pushed us into a dangerous loop. According to WHO, of all non-pandemic-related deaths that happened in the year 2021, a massive 75% (43 million) occurred due to non-communicable diseases.
All of the above are felt at the individual level. One the other hand the global scenario is grimmer – environmental pollution, habitat loss, biodiversity loss, global warming, climate change, energy crisis, increased frequency and scale of natural calamities, new viruses and pandemics. All for what? To support a huge human population and feed the big mouths of an elite minority. The noose is tightening from all corners and many of us don’t even realize it.
Is agriculture actually history’s biggest fraud?
Calling it history’s biggest fraud will be a very strong opinion and can come off as radical. We need to interpret the literal meaning of the phrase without too strong an emotion attached.
The scale of the event does make it history’s biggest. As for it being a fraud, it did trick us into believing that we were in control, that we were moving towards a state much more stable than the previous stages, that we were improving and advancing in the evolution game. While all it did was mess with millions of years of biological evolution our ancestors went through and now we are stuck at a stage where our physiological adaptations are no longer in harmony with our environment and lifestyle. Cultural evolution offered us a short-cut, but our biology just couldn’t keep pace with it.
How the tragedy unfolded?
For millions of years our ancestors had moved across the landscape in groups occasionally settling at places temporarily, mostly dependent on a hunter-gatherer lifestyle. Being continuously on the move meant that their lives were full of uncertainties – they were uncertain about the availability of food in their next stop on the way, uncertain of dangers like unknown wild beasts lurking in the jungles or other human tribes they might come across and if it will be necessary to fight them.
However, when humans started learning the art of crop cultivation and animal domestication they realized that it could provide them with a continuous supply of food and bring about a certain level of certainty in their lives. Clearing jungles to make land available for cultivation kept away wild animals from their settlements hence saving many a life from deadly animal attacks. The wanderer-hunter-gatherer lifestyle put restriction on the number of children women could conceive as more little children in the group meant higher vulnerability for the entire group which ultimately slowed down their movement. Human children unlike any other primate needed more parental care so birth had to be properly timed to match abundance of food and times of peace which extended the gap between two pregnancies.
The population boom happened after humans started to settle down, domesticate animals and cultivate crops. The supply of food was now under their control which conferred them with stability. Sedentary lifestyle and a full stomach removed the restriction on birth rate – more children were conceived and populations grew. But, agriculture narrowed down the range of food items previously consumed, limiting it to only a few cereals and vegetables. Growing populations put pressure on agriculture demanding a raise in food production. Studies point towards reduction in stature and robusticity after commencement of the agricultural revolution proving that nutritional deficiency and diseases were common.
Domestication of animals brought humans in close proximity with them and they were often housed in the same quarters. This created a favourable situation for zoonotic spillovers to occur. New diseases arose and pathogens began to use both the animal and the human as hosts. Crowded settlements made pathogen transmission easy with communicable diseases taking the form of epidemics. Since, humans became dependent on a handful of crops, events like natural disasters, climate anomaly and diseases often caused crops to fail and famines were the outcome.
Apart from that, agriculture formed the base on which civilizations were built. The arrival of a novel lifestyle sowed the seeds for a number of maladaptations, which gradually took shape into “diseases of civilization”. It is only now that we are beginning to feel its wrath. Modern technology and new pathological assessment techniques have helped us uncover some of the links between chronic non-communicable diseases and the cultural evolution that have so intimately shaped our modern lifestyle.
Impact of the Agricultural Revolution on the human physiology
Nutritional deficiencies
Our hunter-gatherer ancestors consumed a variety of seasonal food products offered by nature for millions of years. Our genome evolved accordingly, adapting to the environment. The shift to an agricultural mode of life brought about a sudden change in that environment. Variety was lost from our diet with people becoming more dependent on a handful of cultivated crops and domesticated animals for nourishment. This narrowing down on food variety couldn’t suffice our nutritional requirements and the results were evident.
A study of archaeological remains reveals that our agricultural ancestors suffered more from nutritional deficiency diseases that did their hunter-gatherer ancestors. Analysis of juvenile long bones says that growth was stunted in agricultural populations as compared to foragers. Physiological stress indicators like cribia orbitalia (anemia), porotic hyperostosis (iron deficiency) and tooth enamel defects (calcium deficiency) characterized early agriculturalists. Some regions showed a fall in stature of individuals after adoption of agriculture. Bone health is an indication of nutritional status and bone absorption results from nutritional deficiency. Greater bone remodeling rates were found in maize agriculturalists in Ledder sites compared to foragers which may be the result of low calcium-phosphorus ratio in diets. Tooth size reduction, dental crowding and occlusal abnormalities arose due to consumption of softer food following agricultural intensification.
Humans cannot synthesize vitamin C, so we must depend on external sources for this essential nutrient and the vitamin being water soluble is regularly excreted from our systems. Vitamin C obtained from meat was enough to suffice daily requirements of hunter-gatherer populations but after agricultural revolution cereals dominated and both fruits and meat decreased in our diets. Scurvy (Vitamin C deficiency disease) was thus very common in our farmer ancestors.
Bone health
The human body was adapted for flexibility and movement. The sudden shift to agriculture restricted our range of movements to only a few types of activities surrounding crop cultivation and house building. Repeated use of certain body parts, stress on joints and unusual movements caused problems like arthritis and bone malformations. The root cause of back problems, neck stiffness, spondylosis and joint inflammations stems from our switch to an agricultural mode of life and the later lifestyle changes that followed along with it.
Evidence for the incidence of osteoarthritis and osteophytosis were found to be comparatively higher in some agricultural populations than their forager predecessors.
Lactose intolerance
Milk is unanimously considered nutritious and a rich source of protein – a complete food in other words. But adult humans were not naturally adapted to process milk as a food. What enables newborn babies to digest mother’s milk is the active lactase gene that helps break down lactose, the main disaccharide in milk, metabolically. As the baby grows, its need to digest lactose decreases as it now becomes accustomed to other food items for nutrition. So, the lactase gene is turned off in human adults. However, with the domestication of animals, milk became a food item in those communities and the lactase gene persisted in adults as an adaptation to changing food choices. This phenomenon is called lactase persistence. But lactose intolerance or the inability to digest lactose still exists in some communities like South Americans (50-80%), American Indians (100%), East Asians (100%), Ashkenazi Jews (60-80%) and Africans (60-80%). Lactose intolerance is now a common disease affecting some 65% of the global population.
Dental health
Antemortem tooth loss and dental caries characterized our ancestors, marking the growing emphasis of carbohydrate-based foods following the shift to agriculture. Some newly established agricultural societies prepared plant food by grinding and boiling them into a pulp like consistency that were more likely to be deposited in the gaps and fissures of their teeth. These stuck food materials promoted the growth of bacterial colonies, which upon fermentation of those carbohydrates, released organic acids responsible for eroding the tooth enamel.
Periodontal disease showed a marked increase after adoption of agriculture. Study of dental calculus of our hunter-gatherer ancestors have revealed that they had lesser variety of microbes associated with periodontal diseases and caries. Samples after the agricultural revolution had more cariogenic bacteria. Oral microbial diversity also decreased after the shift to agriculture.
Our current food habits, which are the result of agricultural revolution followed by the industrial revolution much later, is the root cause of dental illnesses that plague us till this date.
Cancer
Today a heavy 86% of the global population (statista) consume meat but the adaptation for it started long back when our ancestors made stone tools to scrape pieces of leftover meat from carcasses after the predators have had their share. It is said that meat consumption may have promoted our brains to develop faster by providing an energy and nutrient dense food source. But today it has posed somewhat of a risk for meat consumers across the world. Heavy meat consumers, especially red-meat consumers, face a high risk of colorectal cancer due to the development of antibodies against a carbohydrate (N-glycolylneuraminic acid) which is derived from red-meat.
When we eat food, we do not simply consume nutrient-rich blocks of energy, we take in a lot of non-food molecules which pose a serious threat to our physiological systems if not neutralized by our body. Enzyme systems thus have evolved to detoxify these xenobiotics which could be toxins and carcinogens. With the shift to an agricultural lifestyle, changes occurred to these enzyme systems.
The enzyme arylamine N-acetyltranferase 2 (NAT2) is an important enzyme responsible for the detoxification of carcinogens and metabolism of various drugs. The NAT2 gene has variations and can be classified into slow acetylator genotypes and fast acetylator genotypes. The slow acetylator genotypes are said to be more prevalent in populations with longer agricultural history as it posed as an adaptation in these populations. However, the adaptation later turned against our advantage.
People with homozygous slow acetylators genotypes are more prone to prostate and bladder cancers. They are also being highly susceptible to drug side-effects for drugs are acetylated to their neutral forms slowly, thus staying in the system longer prolonging their toxic side-effects. Fast acetylator genotypes are however more prone to colon, lung, breast and laryngeal cancers. In such a situation slow-fast heterozygotes are at an advantage because fast acetylation can be advantageous for those molecules whose acetylated forms are neutral and slow acetylation can be advantageous for molecules whose acetylated forms are toxic.
Cardiovascular diseases
High salt (Sodium) consumption is responsible for increased risk of cardiovascular diseases. In ancient times salt served as a rich source of essential minerals which were generally found in trace amounts in food. The salt we use today is heavily processed to its purest form, sodium chloride, with small amounts of sodium iodide (which was later added to cure iodine deficiencies) – eliminating the impurities which may contain other minerals.
Modern fast food and processed food contain heavy amounts of salt which is giving rise to sodium-potassium imbalances in the body. Previously our diets contained ample amounts of fresh fruits and raw vegetables which are rich sources of potassium so that the sodium-potassium ratio was low. Our present diets have high sodium-potassium ratios which results in high blood pressure, hypertension and affects heart health. In some tribal communities, where they still follow the hunter-gatherer diet rich in raw fruits and vegetables, incidences of heart diseases are low to absent. The Yanomamo Indian tribal people, living in present day Brazil and Venezuela, who still follow an ancestral diet to this day deserve special mention here because the blood pressure of 50-year-old members was 100/64 mmHg and urinary Na/K = 0.007, starkly different from values commonly found in modern humans.
Red meat consumption is associated with coronary artery disease and neurodegenerative disorders. Trimethylamine-N-oxide or TMAO, the metabolic byproduct of L-carnitine which is found in high concentrations in red meat, has been observed to promote atherosclerosis.
Obesity
Insulin resistance which evolved as an adaptation to deal with the high protein low carbohydrate diet of our hunter-gatherer ancestors has posed as a problem for our high calorie diets at present. The highly processed food we eat today have high glycemic indexes and are high in carbohydrates. The body responds by storing these extra calories as fat tissue in our body giving rise to obesity. Low physical activity, characteristic of sedentary lifestyles, accompany the diet further aggravating the problem. Our bodies were adapted for flexibility and motion but our current lifestyle starting from the emergence of agriculture leave little scope for any.
The high incidence of obesity among indigenous populations tell another story. Our genetics evolved to fare us through times of feast (abundance) and famine (scarcity). In times of plenty our bodies stored the extra calories as adipose tissue for later use during times of food shortage. Our hunter-gatherer lifestyle was full of uncertainties thus turning this trait into an advantage. Indigenous people today are still not properly adapted to the stability of food supply and modern processed food with high calorific value. As a result of which the ancient trait, which is still operational, is manifesting itself as obesity in these populations.
Type II diabetes
In hunter-gatherer populations meat took up a fair portion of the daily diet with carbohydrate rich foods taking a backseat under certain climatic conditions like those of the ice ages. As humans became more dependent on meat for his energy and nutrition, gluconeogenesis was favoured along with peripheral insulin resistance. With the advent of agriculture, cereals and other carbohydrate rich foods comprised a large percentage of the daily human diet. However, we did not get enough evolutionary time to transition into this phase and what were once adaptations are now proving to be maladaptations. Insulin resistance which was an adaptation to a meat-rich diet is the cause behind high blood sugar, type II diabetes and obesity that plagues society today.
Autoimmunity
Autoimmune diseases have been on the rise recently. The main culprits are said to be environmental factors and an existing genetic predisposition of the victim. The use of pesticides in modern agriculture and excessive processing of food have introduced novel chemicals or antigens in our diet that triggers our immune system in an abnormal manner prompting the body to mount an immune response against its own cells (autoimmunity). The incidence of rheumatoid arthritis has been found to be high in farmers who have been exposed to certain categories of pesticides.
But this is not a very recent phenomenon for research has found a link between the agricultural revolution and the rise of autoimmune diseases. A squeeze in the variety of food consumption that accompanied the agricultural revolution led to a drop in the diversity of the oral and gut microbiome. The gut microbiota has an important role to play in the development of the immune response to antigens. The systematic dysbiosis of the gut followed by the advent of modernization which brought about drastic dietary and environmental changes further interfered with the normal training of the immune system. An uneducated immune system is therefore the main reason behind various immune malfunctions including autoimmunity.
Agriculture marked a shift towards a cereal based diet in most populations. Gluten and other food molecules (fructose, glucose, sucrose, refined carbohydrates, PUFA) are known to increase intestinal permeability which allows the uptake of undigested dietary peptide complexes into the blood stream. These dietary peptide molecules provoke the immune system to respond. Some of these dietary peptides are identical to normal cell proteins of the body. After the dietary peptides are cleared from the system the remaining active immune cells now attack the self-peptides which are similar in structure to the dietary peptides hence giving rise to an autoimmune response.
Deposition of immune complexes in joints and blood vessels cause inflammatory tissue damage in rheumatoid arthritis patients. Certain foods seem to aggravate the symptoms in these patients and high immunoglobulin (IgA, IgG, IgM) levels have been recorded after consumption of those food items. The antigens responsible for the heightened immune activity appears to have arisen from cow milk, cereals, hen’s eggs, pork and cod. Consumption of cow’s milk is also associated with multiple sclerosis, another autoimmune disease.
Exposure to aerosolized pig neural antigens can induce polyradiculoneuropathy (an autoimmune disorder that affects the peripheral nervous system). Pig has been found to contain the highest number of epitopes that match the autoimmune disease associated epitopes amongst all the commonly consumed food items analyzed in a study. Red meat (beef, mutton, chevon, pork) as a group ranks highest with the most shared epitopes associated with autoimmune diseases. Communities with diets dominated by one or few food items known to contain autoimmune disease associated epitopes are more at risk of developing autoimmunity.
Inflammation
The shift to a largely carbohydrate-based diet altered the gut microbiome. The gut microbiota has a crucial role to play in the processing of ingested food and how the body reacts to it. The dysbiosis that followed the agricultural revolution set the stage for inflammatory diseases to arise. Research has shown that increased proportion of high glycemic food in diet leads to an increase in inflammatory markers.
The intake ratio of omega 6/omega 3 in modern western diets is 10-20:1, a steep jump from 2-3:1 characteristic of the hunter-gatherer diet. PUFAs have a role to play in the normal resoleomics (the process by which the immune system resolves an inflammation) response and a change in the balance disrupts the normal response of the immune system to inflammation. High ratio of omega 6/omega 3 fatty acid has an inflammatory effect on tissues. Administration of omega 3 supplements to patients suffering from rheumatoid arthritis, inflammatory bowel disease, asthma, psoriasis and breast cancer (all inflammatory diseases) have shown some remission of symptoms.
Industrial processing of food has introduced many non-food molecules into our diets. Examples include polysaccharides like carrageenans and sulphated polygalactoses. Research evidence suggests that these molecules have roles in various inflammatory diseases of the gut and other organs like inflammatory bowel disease.
Zoonotic spillovers
Never before have humans been in closer contact with animals than after the agricultural revolution. They settled down and cultivated crops and domesticated animals. Animals were often kept in the same quarters where humans lived which gave parasites and pathogens of the domesticated animals the opportunity to explore their new human hosts.
As humans were now sedentary by nature, living in crowded settlements, diseases spread very easily. Living conditions were bad – there was no proper sewage system, unhygienic conditions prevailed and human faeces piled up that created the perfect haven for disease causing organisms to breed. Lack of a balanced diet, nutrient deficiency and excessive carbohydrate dependency weakened immune systems further promoting the spread of diseases that often took the form of epidemics wiping clean villages of its inhabitants. Storage of food grains invited another devil – the rodent – who is the villain behind the spread of numerous communicable diseases.
The diseases our early farmer ancestors passed down to us include tuberculosis, plague, smallpox, measles, typhus, malaria, brucellosis, salmonella and hepatitis B to mention a few.
Conclusion
With a growing body of knowledge and better pathological analysis techniques we have been able to uncover a limited few of the many reasons behind the rise of civilization diseases in the recent past. We have realized that after all we are not as highly evolved as we think ourselves to be. Cultural evolution has fast-tracked our journey, but our biology has put a brake on the speed with which we decided to advance. The rise of chronic non-communicable diseases or ‘diseases of the civilization’ as we like calling them is one such proof. This clash between the biology of the body and the culture of the society have created a stressful environment for us. The choices we make now shall be very crucial for the well-being of the upcoming generations.
Agriculture cannot be excluded from our culture now but the choice of food and how we eat them can be changed. We should increase the variety of foods we eat, decrease our meat consumption, include more whole grains and green leafy vegetables in our diet so that we obtain all the necessary nutrients our body needs. Exercising more often and cutting down on processed high calorie foods should be the first step to a healthy life. Decreasing environmental pollution, building a cleaner surrounding, reconnecting with nature and synchronizing ourselves to nature’s rhythms should be our vision. We should stay more conscious of the food we consume and promote natural organically grown foods.
After all, we are what we eat! A proper diet and a healthy lifestyle can put many of our recent maladies to sleep.