One of the most fascinating topics I have found, is looking into the evolution of diet. Our modern diet is dictated by culture, media and what is available in the supermarkets. It is difficult to navigate what is good for our bodies or what is another fad diet. I am still impressed by the guy who ate nothing but potatoes for a year managed to lose 10kg in the first month.
I wanted to have a look at both the history of humans and how our bodies have evolved to digest food. Hopefully this can give me an insight if the vegan diet is the optimal solution not only for our planet, but for our bodies.
Hunter and Gatherers
Until agriculture was developed around 10,000 years ago, all humans got their food by hunting, gathering, fishing. Commonly named the Hunter Gatherers. This meant humans were living on a varied diet with an active lifestyle, nomadic in search of their food. This is often referred to as the Stone Age Diet, with a focus on diet which ideally fits our genetic makeup. The diets of living hunter-gatherers, discussed a little later on, include 73% of the societies depending on meat for up to half their calorie intake. This data produced the Paleo-diet which encourages to eat plenty of lean meat and fish, no dairy products, beans or cereal grains. The theory is if we stick to the food’s our hunter gatherer ancestors once ate, we can avoid the diseases of modern civilisation including high blood pressure, cancer, diabetes and heart disease.
Is this the case? Or are there other diets which are better for our bodies?
Does this mean our evolution is closely linked to meat? Is it vital for the development of human kind as we know it?
Meat Made Us Human?
Research suggests that humans began hunting for meat to survive on the African Savanna. In comparison to the plant diet of apes, Homo erectus took in enough extra energy from the calorie dense meat to fuel a bigger brain. This however does not make sense, since the brain is fuelled by starch (glucose in particular). What we do know for sure is ancestors of human’s also developed smaller guts which were no longer needed to process large amounts of plant matter. If the two brains are compared now, the human brain required 20% of the body’s energy while resting while the ape’s brain only requires 8%. I am not a brain expert, but I found a really cool article about the comparison between ape and human brains here.
When agriculture boomed, humans experienced another shift in their diet. Moving from plants, to calorie dense meats and now onto a monotonous diet of domesticated grains. Sorghum, barley, wheat, corn and rice ensured that farmer’s had a predictable and dependable form of nutrition. The domestication of grain began a long journey to plant domestication, allowing modern day supermarkets to have unrecognisable fruits and vegetables from their wild counterparts. Just look at some of these examples!
Farmer’s were able to store the grain over winter to feed their growing families. This increased the human population, as a farmer’s wife was able to bear babies every 2.5 years in comparison to 3.5 years for hunter gatherers. While the population soared this did not mean that human’s became healthier. Farmer’s diets became far less diverse in comparison to the hunter gatherer’s diet causing cavities and periodontal disease to develop which had never affected the hunter gatherers. This resulted in farmers to suffer from iron deficiency and shrink in stature. The domestication of animals also had side effects, as consuming their meat and milk lead to parasites and other infectious diseases. These still exist in modern day society, however rigorous health and safety laws attempt to minimise these foodborne illnesses. Then again, we all heard of mad cow disease and salmonella?
Considering the historical findings, the hunter gatherers and their diet of meat and wild found planets appeared to be healthier than the farmers counterparts. The hunter gatherers however, endured lean times and ate less than a handful of meat each week as their meals depended on hunting. In contrast, the farmers had an easy access to larger quantities of meat from their livestock.
Looking into the past by looking into the last existing tribes
If looking at the tribes that exist today, The Hadza and !Kung bushmen of Africa are successful on 50% of their hunts. These ‘modern’ tribes have bows and arrows in contrast to our ancestors, this suggests that capturing the meandering antelope without weapons would have yielded fewer successful hunts. No ‘hunter’ and gatherer tribes therefore eat that much meat, with the exceptions of people in the Arctic. The Arctic Inuit and other groups get as much as 99% of their calories from marine life. The evidence from these living hunter gatherer tribes proves that while they wanted meat they actually lived off plant food. The Hazda get 70% of their calories from plants, the !Kung rely on tubers and mongongo nuts, Tsimane and Yanomami Indians of the Amazon on plantains and cassava and Australian Aboriginals on nut grass and water chestnuts. Significant research has been done on many of these indigenous groups showing that heart disease is almost exclusive to modern societies while other sources have shown evidence of heart disease in Egyptian Pharaoh’s.
Humans therefore evolved from plant eating creatures, to eating meat during the Paleolithic period. Since then however, we have continued evolving. Our teeth, jaws and faces have gotten smaller, as well as our dietary preferences and requirements. One of these examples is lactose tolerance. While all babies depend on their mother’s milk as a life source, cattle only became domesticated 10,000 years ago. Once babies were weaned, their bodies stopped making the enzyme lactase which breaks down lactose into simple sugars. Once cattle became herded, it became advantageous to digest milk. Cattle herders in Europe, Middle East and Africa therefore developed a lactose tolerance in comparison to cultures which did not depend on milk such as Chinese, Thai, Pima Indians of American Southwest.
So Do We Need Meet?
Considering the implications of the livelihoods of our ancestors, we are what our ancestors ate. Our genetic makeup gives us the foundations and abilities to thrive on a large variation of food. Human success is clear due to the adaptability in our diets, traditional diets include vegetarian of India’s Jains, fish-heavy diet of Malaysia’s Bajau People, meat-intensive of the Inuit or protein from insects in many areas of Thailand, Ghana and China amongst many others. The big difference between us an our ancestors is how we come about our food.
While humans have eaten red meat for two million years, heavy consumption increases cancer and atherosclerosis in most populations. This is due to our gut bacteria and its relationship with a nutrient in meat named L-carnitine. L-carnitine boosts artery clogging plaque. Neu5Gc from mammalian meats exists in the walls of the gut microbes and human cells found in the gut and in tumours. Eating beef and pork can potentially trigger inflammation and the possibility to develop into cancer due to overlong exposure.
The Modern Diet
The next revolution in the modern diet was when humans learnt to cook. Our ancestors began cooking between 1.8 million and 400,000 years ago. (I know, not very precises huh?) Cooking food predigest it, requiring our guts to spend less energy breaking it down and extract more to fuel our brain. Cooking therefore gave early humans the energy to build bigger brains and gain weight. Nowadays humans have come full circle, eating more calories than they burn in a day. From rough bread to isles of cookies, from oranges to orange juice, from porridge to white pasta and bread. Humans over eat processed foods, sugars and simple carbs causing the obesity epidemic and related illnesses.
What Does Our Anatomy Say?
In the past six million years not only has our diet evolved, but so has our face. This incredible video showcases a sped up evolution
of human faces. Through out it, you can see that while certain aspects shrank like our jaws and noses, our skulls reshaped to house a larger brain. Physiological factors effect the bodies need for food, these include hunger controlled by a gland in the brain called the hypothalamus. The hypothalamus has additional functions in the body including controlling body temperature, thirst, inducing sleep and wakefulness and release of growth and sex hormones. Maybe this is why after you’ve had a big meal you have the need for a nap.
Additional factors include nutritional requirements depending on body size, age, level of activity, gender and health status. The last factor is human reaction to food. Humans use their senses to pick their food based on their presentation, smell and texture. These desires are individualised based on culture and upbringing. I have many times heard humans referred to as omnivores.
The animal kingdom is generally split up into three diet types. The carnivores are creatures who’s diets are made up of meat. These can be further sub-categorised into animals living off mammalian meat, fish or even insects. Typical examples are lions, tigers and the whole feline family. Herbivores are organisms that only eat plants creating a vital part of the food chain, as they can digest the plants. Plants are the only organism which can create energy from the sun making them the start of the food chain. Herbivores also have subdivisions classifying animals which eat fruit (Fructivores/Frugivore), leaves (Folivore), nectar (Nectarivore), seeds (Granivore) , pollen (Palynivore) or plant fluid (Mucivore). Omnivores are merely classified as organisms which can digest both meat and plant matter.
Scientists are able to distinguish the nature of an organisms diet through observation or by studying their anatomy. The digestion of meat and plant matter requires significantly different teeth, stomach acids, metabolism and internal biological structure. Have you heard that cows have four stomachs? Turns out they only have one, but with four different compartments with individual purposes. Grass is extremely hard to digest and requires a four part system you can read more about here. Due to this, herbivores tend to have intestines 20 times the length of their body in comparison to carnivores which only have intestines 1.5-3 times the length of theirs. I found this handy table below with a comparison of many of these characteristics.
Looking at this list of physical characteristics, the omnivore classification has several big differences with the human anatomy. Humans have relatively blunt canines and flat incisors in comparison to sharp fangs, however this may be due to the ability of cutting up meat into smaller pieces rather than ripping it off a carcass. The acid found in human stomachs is significantly weaker, while fiber is required to stimulate digestion, our intestines are also 3 times longer than majority of the omnivores. This anatomical comparison gives an insight to the ideal diet our bodies are designed for. Maybe this is why people switching to veganism have found such enormous health benefits, with frequent mentions of the feeling of ‘lightness’ and ease of digestion.
This is part of the reason why I get extremely frustrated when people force their vegan lifestyle on their pets. Cats especially, cannot digest plant matter, as they are 100% carnivorous. The only time they do eat grass, is to purposefully make themselves throw up, find out more here. A Board certified vegetarian nutritionist Cailin Heinze states that the vegan diet is innapropriate and completely against the cats physiology. Dogs on the other hand have a more adaptable pallet and can live healthily on a vegetarian diet. This of course can be extremely risky, and just like transitioning to a vegan diet as a human, we need to be careful about supplying enough vitamins and protein.
What the scientists agree on, that while there is not one universal healthy diet modern diets have become extremely high in processed food with a heavy focus on meat. This combination does not replicated the diversity of foods our ancestors ate, and thrived off of. They also had the added factor of active lifestyle to protect from heart disease and diabetes. The modern man behind a desk job is slowly killing themselves through consuming the modern western diet. The unified conclusion of scientists is to maintain a healthy life, people should shift away from processed foods and back to whole foods. People should gain a focus on eating more local fruits, vegetables and if they must subsidising their diet with little meat, fish and whole grains. While nutrition is 80% percent of the battle to weight loss, the other 20% is staying active and exercising daily. Complex carbohydrates are the fuel to our brain and vital to our health. Not all Carbs are bad unlike the media would have us believe!
Human Diet Evolution
What can we conclude?
The human diet evolution has shown us that first and foremost we are adaptable. If veganism is the answer to the environmental problem, is it not a viable alternative to strive towards? When comparing the anatomy of various animals and humans, it can be seen that our physiology is the closest to fructivores. The transition that occured many years ago when our ancestors ate meat helped us develop our large brains. Potentially, the next step of our evolution is moving away from that.
After all, do human’s really need bigger heads?