An Argument for a Plant-based Diet

Health, Medicine, Public Health, Society / By Keyvan Golestaneh / August 19, 2020 January 12, 2022

There is an increasing debate between those who believe meat is essential to human diet and health, and those who do not. One side believes we should not eat meat because it’s bad for our health, and many also use ethical and moral reasons to justify it. The ethics of killing animals is a very controversial subject. Vegans believe that as sentient beings who feel pain animals should be treated the same way as humans. That is a valid, well-reasoned argument, but because it’s an emotionally charged subject, going against thousands of years of cultural conditioning, many people are not receptive to it. It’s very difficult to convince people to change their behavior by “shaming” them. People respond better if they have a positive reason to change.

In addition to the ethical reasons, vegetarians, vegans, and raw food diets use the study of human evolution to justify their perspectives. They claim that humans evolved as plant-eaters and use anatomy and physiology to back up their arguments. Opposing them are advocates of the standard meat-centered diets, low-carb, Paleolithic, and Keto diets. They also turn to human evolution to explain and justify their beliefs. But the evolutionary and anthropological evidence clearly shows that both the plant-based and meat-centered, low-carb advocates are mistaken, but for different reasons. What Paleo and Keto advocates think of as a typical prehistoric human diet is a partial imitation of what paleo-anthropologists know about it. Though I support the use of evolution and ethics as a guide to diet and lifestyle, let’s set aside the ethical issue for now and focus on current science, ecology, and evolutionary anthropology.

In the spirit of science, we need to look critically at our own assumptions and conclusions, and test them against the empirical evidence. To help us get beyond popular beliefs and personal bias, it’s necessary to look at the full spectrum of available research and evidence. One of the most persistent, pernicious modern myths is the need for protein. Let’s put to rest the myth that non-meat eaters don’t get enough protein. Depending on age and weight, a minimum of 45-55 grams of protein per day is all that is required. On average non-meat eaters get 20% more than they need. The focus on protein by Paleo and Keto advocates perpetuates this myth. It’s fiber that most Westerners don’t get enough of. We should also not underestimate the complexity of the human physiology, individual bio-signature (genetics and constitutional type), and humanity’s changing relationship to the environment.

It is popularly assumed that evolution is primarily determined by genetics; that is inaccurate. Evolution is determined by the relationship of an organism to the environment, which is why we cannot explain genetics separately from the environment animals live in. How well humans adapted to past environments, and what is now required to adapt to fast changes in the global environment and cultures, are key to individual health and humankind’s success as a species.The principle reason for adopting a plant-based diet, that includes and even maximizes raw foods, is that it engages and accelerates our evolutionary potential—at the level of biology and consciousness. A plant-based diet is closer to what our primates and hominin ancestors ate. Adopting this diet is an ideal, adaptive response to climate change, over-population, and sky-rocketing medical costs. The connections between human culture (the anthrosphere) and the earth’s ecology (biosphere) can no longer be ignored. Ecological and anthropological data reinforce clinical evidence and provides solid support for why a plant-based individualized diet is the best choice for the majority of people; it also provides the greatest benefit to society and the planet.

Mankind rapidly evolved because of its use of fire to cook meat and fibrous foods. Cooking was a revolutionary development that heavily impacted both human biology and social relationships. It initiated the co-evolution of the brain and culture. This technology radically changed human diet, providing the fuel needed to accelerate the growth of the brain which doubled in size by the time Homo Sapiens emerged. The increase in carbohydrate consumption was a central part of that process. Cooking wild game meat, which unlike modern livestock is very low fat, and root-vegetables found in the savannah (open grass land) made nutrients more bioavailable (absorbable).

Cooking was an efficient way to absorb more nutrients and calories, and it also freed up time for activities other than hunting and foraging for food. Eating together became central to social life because of food preparation and cooking. A larger brain and increased cooperation, in turn, provided the foundation for higher forms of cognition and more complex cultural behavior that required more sophisticated means of communication through language. These developments were all necessary for the emergence of more complex societies and, eventually, civilization. Homo Sapiens could not have evolved into what we are without the benefits of fire and cooking.

Early humans lived a hunter and gatherer lifestyle, where tubers (high fiber carbohydrate root vegetables) were a common food. Tubers aren’t easily digested and need to be cooked to breakdown the cellulose structure enough to assimilate its nutrients. 99% of human existence consisted of a high fiber diet. Early humans only ate 10-19% animal protein, far less than what Paleo and Keto diets recommend. The human brain needs 60% glucose to work, which you cannot get from meat. To increase in size the brain needs more glucose and protein. Protein does not provide glucose, only carbohydrates found in plants and fruits do. Humans were essentially faunivores and frugivores, with occasional animal protein. In other words, prehistoric humans were flexitarians and took advantage of what they could, when they could, which also meant it was either “feast or famine.” Calorie restriction, also known as fasting, was a natural unintended part of a human’s life; as long as it didn’t go on to long, it was very beneficial to the health of the body. During a two-million-year time span, this ancestral dietary lifestyle made prehistoric humans into the complex cultural beings we see today.

The Paleo and Keto diets are very similar. They recommend animal protein, fats, low carbohydrates, fruits and nuts, and nodairy, grains, or beans, but they do so for different reasons. Except for animal protein and low-carbohydrates, these are excellent recommendations central to a plant-based diet. The Keto diet focuses on changing the proportions of macronutrients (carbs, fats, and protein) by increasing protein and fats and lowering carbs, so the body gets energy from fats, not carbs. The Keto diet recommends a higher fat intake then the Paleo diet. This maintains ketosis, where the body burns fat instead of carbohydrates for energy—something not emphasized by Paleo advocates. The Paleo diet is a lower carb diet because, for example, they allow fruits, but they do not emphasize it as much as Keto advocates. The Keto diet also allows dairy and soy, while a Paleo diet does not. One downside to the Keto diet is that low-carb consumption can cause hypoglycemia for some people.

The Paleo diet is based on the idea that humans should follow the diet our prehistoric, Paleolithic ancestors ate, which they say consisted only of meat, nuts, fruits and non-cultivated vegetables. Cultivated plants, like grains and legumes, are excluded because Paleo followers claim humans did not eat them until the emergence of agriculture approximately 12,000 years ago. But the evidence shows that humans started consuming wild grasses (grains) as far back as 2 million years BP, after they transformed from forest-dwellers to living in open grass land savannah habitats. The problem is Paleo advocates have a selective and incomplete view of what prehistoric humans ate. They also focus only on the last 2.5 million years of human evolution, ignoring the previous 25 million years of primate and hominid evolution that consisted of a diet of 90% high fiber plants and fruits and only occasional wild animals, a diet that contained very little fat.

Unhealthy levels of cholesterol were never a problem for most of human evolution because there is none in plants. Because cholesterol is essential to cell membranes, the brain, and hormone production, the body developed a genetic predisposition to preserve it. What little cholesterol was consumed was conserved because it was in short supply. Note that carnivores, like wolfs and bears, never develop high cholesterol because their bodies (genetic) can easily manage it. The human body does not easily eliminate cholesterol (which requires high fiber), therefore a dietary lifestyle that depends on meat consumption does not benefit the body’s health. Humans are maladapted to Western civilization’s meat-center, high saturated fat, low-fiber diet, and sedentary lifestyle.

A large percentage of humanity needs to re-adapt by changing their dietary lifestyle. The human groups that come closest to a prehistoric diet are found in rural Africa and China, where they mostly eat a high-fiber plant-based diet, with only occasional meat. These populations have none of the diseases commonly found in Western countries. Using current anthropological data, we can correct the misleading information used by Paleo, Keto, and low-carb advocates popular with the public. The clinical evidence shows that long-term, meat-centered diets are unhealthy and create the ideal conditions for disease.

Paleo and Keto diet advocates correctly identify insulin imbalance as one of the principle causes of major diseases, like heart disease, diabetes, metabolic syndrome, and chronic obesity. Insulin and hormonal levels control metabolism, and a healthy metabolism is the key to preventing the most common ailments and diseases. The goal of these diets is to lower insulin by consuming less carbs, which results in weight loss. They ignore the fact that animal protein can also increase insulin—even higher then pasta can! They also neglect the long-term risks of high cholesterol. LDL (“bad” cholesterol) and triglycerides goes up in meat eaters, and HDL (“good” cholesterol) goes down. Clinical evidence shows people on plant-based diets have the lowest insulin levels. There is a difference between the short-term benefits and the long-term effect of low-carb, meat-centered diets. Low-carb dieters often rave about the results they get. It is undeniable that people see quick positive benefits, like weight loss and increased energy, by following these diets. The key common denominator among ALL these diets is the elimination of processed, refined foods, dairy, sugar, and the use of whole foods. That is the real reason why people see fast changes in physical and mental health, notbecause they are eating more animal protein!

If all countries adopted a typical Western diet it would have a disastrous impact on the earth’s ecosystems. No matter which angle you look at it from, it is not a sustainable dietary lifestyle. There are now Paleo-vegans, who eliminate animal protein, retain the low-carb requirements, but still eat no grains and legumes. Although an improvement over a Paleo-meat-centered diet, they too read evolution selectively and do not recognize of the negative side-effects of low-carb consumption.

The world has changed DRAMATICALLY since the Paleolithic era. We are no longer at the mercy of the seasons and exclusively local geography for our food and have accumulated extensive scientific knowledge. Thanks to human imagination and advances in technology, a world-wide artificially-constructed environment has emerged that overshadows and threatens the non-human ecosystems. We have entered the Anthropocene era, where humanity is now a driving force, like the weather and geology, in biospheric evolution—with the power to affect and transform the whole planet. The world-wide spread of human civilization, over-population, and its effect on the climate require drastic changes in behavior. Dietary lifestyle, as it turns out, is one of the keys to human and planetary health. There is no reason to assume that because of a widespread reliance on animal protein that we need to continue that dependence into the future. To do so would be economically and ecologically unsustainable. The mismatch between civilization and the environment has reached a critical point. It’s time to open our eyes to what’s happening by thinking forward rather than back. The technologies that have fueled the destruction of the non-human environment can serve to prevent further damage. New technology and scientific knowledge about health, medicine, and ecology provides advantages that, when used wisely, can help humanity find a path out of the escalating crisis.

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