Are Humans Herbivores?

“The (true) claim that vegetarianism is a healthier diet than carnism does not necessitate obfuscating the evolutionary reality of omnivory.” - Gil Henriques

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A popular selling point that advocates of plant based diets use when confronting 'meat eaters' is that humans are ‘natural herbivores’. Physical characteristics such as intestinal length, stomach acidity, teeth, jaws, and nails, as well as psychological characteristics such as slaughterhouse workers having high rates of PTSD have been analyzed in an attempt to prove that there really is one optimal human diet (1, 2). There have also been scientific discoveries regarding early human ancestors which suggest that humans were originally herbivores (1, 2).

This argument, despite being scientifically backed and evidence based, has drawn an immense amount of controversy. I decided I needed an evolutionary biologist to help me understand where this controversy comes from. Gil Henriques, evolutionary biologist and PhD candidate at The University of British Columbia explained that the herbivore/omnivore/carnivore classification is based on a species’s “physiological and anatomical adaptations.” In other words, classifications are based on animals’ ability to eat and digest various food sources that has evolved over time as a result of environment and behavior. By this definition, humans are classified as omnivores because we are capable of eating both animals and plants. Henriques describes humans being classified as omnivores as an “evolutionary reality,” but notes that just because we have evolved to eat meat and dairy doesn’t mean it is always healthy for us.

In order to better understand this concept, we have to first understand why and how humans evolved to eat meat and dairy. Non human animals typically evolve as a result of their surroundings (access to food, presence of predators, etc.), but humans have a unique driving force behind dietary evolution. According to Henriques, “most animals lack culture, but it is a main driver for human evolution.” He explains, for example, that the ability to digest dairy is a direct result of animal husbandry in ancient Europeans, a cultural practice not present in other places which explains why there is such a high occurrence of lactose intolerance in non-European derived ethnicities (1). Humans today live all across the world and have adapted to practice a wide range of cultures, meaning that humans have developed a range of digestive capabilities, which as a species makes us omnivorous.

The term omnivore describes these varying capabilities, but it is not an inherent recommendation as to what diet is the healthiest for humankind. Henriques explains the discrepancy between the food we have adapted to eat and the food most ideal for our health:

“The fact we evolved adaptations to eat meat or milk is meaningless because our current environment and needs are not the same that we faced during most of our evolution. We have access to a balanced plant-based diet which we did not necessarily have during our evolutionary history. Faced with nutrient starvation, adaptations for omnivory may have been adaptive, but that doesn't mean it's "good" to eat meat. It's the same exact thing as how we evolved adaptations to store extra calories as fat because that was adaptive at the time, but in the current environment of abundant calories it leads to widespread maladaptive obesity.”

In summary, just because humans are capable of digesting meat and dairy doesn’t mean they should. When it comes to the optimal diet for human health, and the diet that the longest living civilizations around the world consume (1), plant based diets rein supreme.

That said, everyone is different. Allergies, medical conditions, age, gender, activity level, location, and even preferences and culture mean that we all need to eat with different quantities, cooking methods, or even times of day in mind. And yes, there are circumstances in which a plant based diet may not be feasible or medically recommended. However, for the vast majority, the healthiest base for the human diet consistently points to plants.

That's not to say there's no room for variation. Although sticking to whole grains, fruits, vegetables, beans and other legumes, and nuts and seeds is fairly universal, there is plenty of room for variation within the “plant based” umbrella. Some enjoy eating more raw foods while others prefer every meal to be cooked. Some thrive on minimal fat while others seem to do better with slightly more. Some prefer eating within a few hours of the day while others prefer to graze throughout. The science behind these tweaks and others are the future of individualized nutrition, and are likely a reflection of the influences culture and environment have had on our dietary evolution.

So, are humans herbivores? Technically no, but at the end of the day this is just a technicality that distracts from the vital information that, for most people, plant based diets are the key to long term health.

You may be left wondering how we know, scientifically, that animal foods are harmful to human health, and don’t worry, answers to these questions and more are coming soon. In the meantime, check out the Resource Center to learn more about why plant based diets are so effective at preventing, managing, and sometimes even reversing many of the world’s most common chronic diseases.

@TheGilHenriquesYou can also follow Gil Henriques on Twitter

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