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"Humans are herbivores" is an idea that has cropped up in fringe sections of the vegan community. It is often used as an argument by vegans but can exist as an idea on its own.
Most of the arguments in support of this idea are based on comparative anatomy and physiology, as well as supposedly "common sense" speculations about human evolution. They include the following:
These also ignore that the only natural source of Vitamin B12 is meat or other animal products, such as milk and eggs. B12 deficiency causes pernicious anemia which, as the name suggests, will kill you if left untreated. Indeed, a few vegetarians and vegans every year either die or get seriously sick from improperly managing their diets. Groups such as the American Dietetic Association state that all vegetarians or vegans need to consume supplemental B12 or foods fortified with it.[10] Most primates are able to get B12 from their gut bacteria and absorb it in their large intestine, but human beings have different intestines which can only absorb B12 in the small intestine, even though bacteria still produce it in our large intestines, and we then poop it out unabsorbed. It's not certain exactly when this change in our ancestors' digestive systems occurred, but logically it must have happened when there was already a substantial external source of B12 in our diets, i.e. after we started to eat meat.[11]
Furthermore, it ignores that most larger herbivores aren't themselves strictly herbivores, gnawing on bones and even occasionally meat.[12][13] Deer, for instance, will eat carrion (and even engage in cannibalism), and to acquire the nutrients needed to grow their antlers every breeding season, the males will search out bird nests and devour the eggs and chicks. If given the opportunity, a deer will eat your corpse.[14] Sweet dreams!
The mainstream view of human evolution is that until around 4 million years ago, the ancestors of humans lived in the jungle eating fruits and other soft plants. Around 4 million years ago, Australopithecus moved into the savannah and began eating harder foods, including seeds, nuts, roots, arthropods, small mammals, and possibly carrion or food left by larger predators.[15] Around 2.6 million years ago, australopithecines developed tools, and probably somewhere between 1.7m and 1m years ago, early humans began to control fire, both of which allowed them to consume a greater range of foods, including the meat of large animals.[4] Through all this, humans continued to evolve and change in their ability to catch and consume different types of food, and anatomically modern humans did not appear until 200,000 years ago.
Overall, the argument that humans are naturally herbivores is a pseudoscientific appeal to nature that doesn't even correctly understand "nature". This takes away from the more legitimate arguments for veganism and vegetarianism, such as ethical and environmental reasons. In assuming the choice is between plants and large mammals (bovids, deer, ovids, etc.), it also shows an ignorance of the wide range of non-vegan foods eaten by humans today.
While human herbivoriousness is a myth, it is factually true that human physiology is pretty well adapted to eating foods made from plants. Humans cannot digest plant fibre or plant cell walls like specialist herbivores can, but we can draw nutrition from plants anyway[16], and the symbiotic bacteria in our guts can feed on undigested plant matter to produce interesting micronutrients that appear to contribute to better physical and mental health[17]. There is robust evidence that people who eat a diet that contains a high amount of vegetable and fruit-based ingredients enjoy better cardiovascular health and less susceptibility to cancer[18], and excessive consumption of red meat and processed meat has been linked to cancer[19], although this is difficult to separate out from the fact that people who concentrate on eating lots of vegetables and not overindulging on processed food likely take more care of their health in other ways, too. Just because humans cannot naturally gain all of their essential nutrition from plant sources does not mean human physiology is not best when it gains most of its nutrition from plant sources, and a well-thought-out vegan diet is much more fun to eat and biologically tolerable than the other extreme.
None of this changes the fact that it is irresponsible to promote veganism by lying about its nutritional completeness. Vitamin B12, as well as other micronutrients that are absent in vegan diets, can now be synthesised in laboratories with no animal involvement. Telling vegans that their diets are naturally nutritionally complete can make people sick, especially when combined with lies about getting B12 from unwashed vegetables or mushrooms (which may contain these nutrients, but in biologically useless trace amounts). If you are a vegan, or even a vegetarian in a lot of cases, you need to supplement with Vitamin B12, either from pills or fortified plant milks.
Our ancestors being omnivores is a privilege for our species. Many of the better things about being human, like our excellent colour vision and high intelligence, are adaptations that allowed our ancestors to find different sources of nutrition, and our ability to survive on a wide variety of diets allows us to make more decisions about what we eat than we would be able to if we were obligate herbivores (or carnivores for that matter). While it is impossible to live a life completely free of all animal product involvement (whose manure do you think is growing those plants?), there are many valid ethical and scientific reasons to eat less meat or none at all, and there is no shame in veganism being a decision made by an omnivore.
Categories: [Animal rights] [Clichéed sayings] [Evolution] [Food woo] [Pseudoscience]