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I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

02 July 2010

Taxonomy vs. Diet

An anonymous commenter on my previous post feels I'm confusing taxonomic classification with dietary behaviors:
Humans can indeed live on an astoundingly wide variety of diets and it is remarkable.

However, this is a confusion between taxonomy and diet. Please educate yourself further.
My response:
Actually, anonymous, I'm not confused about the difference at all. On the contrary, the difference is what this post was all about. It is critics of veganism who are confused about the subject, when they tell me that humans are classified as omnivores and therefore MUST eat meat.

However, I will concede that, upon re-reading this post, I can see why you are confused about my meaning. So, thank you for your constructive criticism. I will edit the post for clarity, and put up an entirely new one to make sure there's no confusion.

Note to self: stop posting first drafts!
So first, I should apologize to any other readers confused about the difference because of my last post. Omnivora and Carnivora aren't about diet per se, but about anatomy. I was trying to keep this distinction in mind, because we vegans are often told that humans are omnivores by nature, and therefore must eat animals. That charge is based on the confusion of taxonomy and diet. However, because I didn't take time to read the post before uploading it, I can see where the reader's confusion crept in.

I'm trying to argue on this blog that, at least in the context of the debate over veganism, terms like "omnivore" and "herbivore" are fairly useless. Critics of the vegan way have endowed these colloquial descriptions with a "scientific" authority beyond their actual meaning, and need to have the difference between taxonomy and diet clarified for them. Humans are "omnivores," true; but that is merely the beginning of a discussion, not the end of one.

"Omnivore" and "herbivore" are not, as some vegan critics seem to think, taxonomic classifications. They are mere descriptions of an organism's diet. In the fossil record, it makes sense to call an animal a herbivore because though we know it ate plants, we can't usually tell what parts of the plant it ate. When dealing with extant species, the practice these days is to use more specific terms, like "folivore," "frugivore," or "graminivore." But even then, these are descriptions, not classifications.

This is not to say that there aren't animals with highly specialized diet strategies and anatomies, like the artiodactyls and perissodactyls. But while such "herbivore" animals do not normally eat meat, anyone who's spent time with them knows they're more than capable of it. I've met a horse who's fond of cheeseburgers and hot dogs. Goats are notorious for their omnivory, despite being highly-specialized "herbivores."

Conversely, "carnivores" (as opposed to Carnivorans) are also capable of eating and digesting plant matter. My cat (who's both a carnivore and a Carnivoran) loves mashed potatoes and brown rice, and is always trying to steal them from me. Wolves in the wild are known to eat generous amounts of grasses.

The bottom line is that mammals are highly versatile creatures, who've inherited dietary capabilities from their distant common ancestors. Despite specializations developed over millions of years of evolution, they still retain their basic ability (though not necessarily a desire or a need) to eat and digest a wide variety of foods.

The confusion here, among critics of veganism, lies in the definition of the word "omnivore." Many treat the word as a proscription of food choices, when it's actually quite the opposite. An "omnivore" -- or, as I prefer in the context of the vegan debate, a generalist -- has the fewest restrictions on its choices, and is thus the most flexible. Vegan critics who level the charge that "(h)umans are omnivores, which means that a vegan diet is not optimal for us," fundamentally misunderstand what the word omnivore means. They also misunderstand evolution, in arguing that there is such a thing as an "optimal" human diet to begin with.

A generalist animal -- that is, an omnivore -- can eat both plants and animals. That doesn't mean it has to eat either one, generally speaking, and most focus on one or the other. Primates are generalists capable of eating bugs and animals, but nonetheless eat mostly plants. They obtain some nutrients from insects and small game to differing extents based on primate species, but this doesn't mean they must do so, given other options.

Science marches on, and ethics often follows. There is no dispute that for most of our history, humans have been "omnivores." But, as ethical awareness expands to include nonhuman animals, many people mistake past practices with future or current obligations. Humans do not need meat and dairy; just because we have used them in the past does not mean we are stuck with them.

My previous post was meant to address this misunderstanding of diet and taxonomy. The Carnivora aren't necessarily all meat eaters, and the fact that an animal eats mostly other animals does not necessarily make it a member of Order Carnivora. Membership in that group is based on common possession of a suite of biological and morphological traits, not necessarily on diet (as noted, pandas are herbivorous Carnivorans).

Similarly, humans are not, and never have been, classified as Omnivora, despite our generalist habits. The brief history of Sub-order Omnivora in my last post was meant to highlight, in part, this distinction between taxonomy and diet.

Saying humans are omnivores isn't really telling us much about our evolution, since most mammals could reasonably be described in the same way. It tells us nothing about our dietary or ethical obligations. It is simply a banal observation, the beginning of a discussion, not the end of one.

So, no, Anonymous, I'm not confused at all. And after this, I hope none of my readers are, either.


  1. Thanks, that makes a lot of sense. Maybe I can find a way to segue into this when someone tells me they're a "meat-a-tarian". I do like the point, though, that generally diet has been and is a choice. Great article

  2. Thanks for your post. Very interesting and useful.

    Have you read my book about carnsim, a word I use to distinguish anatomy from ideology? You can get more information at www.carnism.com.

  3. Thanks for another great post. I just discovered your blog--I think it is fantastic. Have you read the book Man the Hunted? If not I think you would find it interesting. It destroys the popular cultural myth used by many paleo-dieters to justify unnecessary killing.

  4. Is there a particular paper or position statement where omnivore was retired?