Are humans, apes, monkeys, primates, or hominoids?

Huxley apesI suspect the correct literary answer is that we are Yahoos, but here I want to do what I would ordinarily never dare do: disagree with John Hawks. John takes Jerry Coyne to task for calling humans “apes”:

Humans are hominoids. Hominoidea is a taxonomic group. Phylogenetic systematics holds that taxonomic groups should be monophyletic — meaning that they include all the descendants of one ancestor, and don’t leave any descendants out. Humans are closely related to chimpanzees and bonobos, more distantly to gorillas, then orangutans, then gibbons. All these living creatures are crown hominoids. The Hominoidea includes all these, together with extinct animals like AustralopithecusProconsulDryopithecus, and many others. Chimpanzees are apes. Gorillas are apes, as are bonobos, orangutans, and gibbons. We routinely differentiate the “great apes” from the “lesser apes”, where the latter are gibbons and siamangs. Humans are not apes. Humans are hominoids, and all hominoids are anthropoids. So are Old World monkeys like baboons and New World monkeys like marmosets. All of us anthropoids. But humans aren’t monkeys.

John is not alone in this argument. I have had it also with my coauthor and cladoclast Malte Ebach. Like Malte, John argues:

“Ape” is an English word. It is not a taxonomic term. English words do not need to be monophyletic. French, German, Russian, and other languages do not have to accord with English ways of splitting up animals. Taxonomy is international — everywhere, we recognize that humans are hominoids.

But there is a flaw in this argument, which John himself alluded to before these passages, quoting Coyne:

I believe it was William Jennings Bryan who denied during the Scopes trial that man was a mammal. That one statement laid him low, exposing his Bible-ridden ignorance for what it is. Of course we are mammals, and of course Richard [Dawkins] is an ape.

The word “mammal” is itself indicative of a process of language change. Prior to Linnaeus defining the term, it was not a part of any European language. In 1758 he defined Mammalia as a technical name and by the early years of the 19th century, the vernacular term “mammal” was used by everyone from the meanest uneducated worker through to the most educated palaeontologist. That’s what happens with languages. Experts introduce and revise terms that the folk pick up. Hilary Putnam called this “division of linguistic labor” “according to which such terms have their references fixed by the “experts” in the particular field of science to which the terms belong” [Wikipedia].

If terms like “dinosaur”, “mammal”, and pre-existing terms like “ape” (now not including Barbary Apes, because experts realised they weren’t apes) and “bird” (now not including bats, because experts, Linnaeus being among them, realised they weren’t birds) turn out to need revision, they get revised, and the usage filters down to vernacular use, sometimes. We even now know that whales aren’t “fish” (although, as I will argue, they actually are, and so are we).

Names are not, in themselves, natural facts. If what they denote are natural objects, then nomenclature is critical in classification; otherwise it really is a conventional matter. So the issue is not are the names right, the issue is whether or not they unambiguously denote facts about the world. And here another core problem arises. Vernacular terms like “ape”, “bird” and “tree” get a major revision by technical science. Some terms, like “mountain” or “stone” can be dissolved either into many technical terms, or spread ambiguously across terms of art in ways that make them scientifically meaningless. When the claim is made in the popular press that “birds are dinosaurs” or “humans are apes”, there is a vernacular sense in which this is simply false. Dino feather Every child knows that dinosaurs are flightless things with teeth and no fur that lived more than 65 million years ago (unless they are well educated into the arcane debates in paleontology; never underestimate a motivated ten year old), so how can birds be dinosaurs?

The answer is, of course, that modern phylogenies (classifications based on shared traits that are thought to be the result of evolutionary history) place the group Aves, the taxonomic name for birds, squarely inside theropods (a type of dinosaur). By the rules of technical biological nomenclature, then, birds (Aves) “are” (fall inside) dinosaurs (Dinosauria).

But this is not how vernacular classifications work. Folk taxonomy is hardly rigorous, and since the words often preceded the science, a degree of revision based on science is inevitable. The technical name “dinosaur” itself entered the English language after they were named in 1842 by Richard Owen. So the claim that birds are dinosaurs is a case of a folk taxonomic term (one that agrees more or less closely with scientific usage) being subsumed under a technical term.

The claim that humans are apes is less clear. In folk taxonomy, “ape” is a term that has no comparable scientific meaning. It basically means any primate that lacks a tail and is not human. “Human”, however, denotes a single and scientifically accepted species (or group of species), so here the claim is that the technical taxon falls within a prior folk taxonomic category interpreted scientifically. This is not new, of course, since Linnaeus famously placed humans (Homo) within the same genus as other apes, a classification that was later changed to reflect folk taxonomic preferences (by Blumenbach, and later Oken).

Now the claim is that humans (Homo sapiens) are apes (Homininae), which is a group defined as the African Great Apes. In short, it is a claim that humans are a species of African Great Ape (and therefore a member of Hominoidea, which includes gibbons and orangutans, also included among these apes). The issue is whether or not the taxon name denotes a natural group. And what counts as “natural” in taxonomy is that the group is monophyletic, or is all of the taxa that can be included without any not being included, in that group. Think of it as a Venn diagram:

Dinosaurs and birds

In the older system, Dinosaur meant the blue part. Now it means the whole outer circle. Some continue to speak about “non-avian dinosaurs” but that’s just a holdover from the past, and the Chinese feathered dinosaurs have undercut even the intuitions that made that worth doing. Here is the human/ape case:

Humans and apes

“Ape” has (once again) been redefined by the experts, and to make a rhetorically memorable point, some taxonomists say “humans are apes”, which is the vernacular way to say “members of Homo are members of Hominoidea” without turning off the aforementioned ten year olds. Any professional that continued to talk about “non-human apes” and meant “non-Homo Hominoidea” should be asked to justify why that is a group of interest, especially as new fossils continue to blur the intuitive lines that motivated the distinction.

It is not possible to stem the tide of linguistic change, as the Académie Française has found out repeatedly. If experts can redefine terms influentially, then there is nothing wrong with that so long as it doesn’t confuse the experts. Using paraphyletic terms (that is, group names that denote what is left of the group once a subset has been removed) is a Very Bad Idea that hangs on in science, but it need not hang on in folk usage. And there’s nothing wrong with saying “humans are apes”, because, on the best construal of what those terms denote, they are.

Neil Shubin’s excellent book Your Inner Fish makes a similar point. Where once a “fish” was anything that lived in water (including swans, geese, alligators and crocodiles, whales, and water snakes), it came to mean a vertebrate that had gills and fins and scales. Shubin shows how the Gnathostomes (jawed fishes) includes land vertebrates, including mammals and ultimately us, as well. Language can change…

See also my post “Is Brian Blessed a monkey or an ape?” where, I now recall, I have disagreed with John Hawks once before on this very issue.

23 Comments

Filed under Epistemology, Natural Classification, Species and systematics, Systematics

23 Responses to Are humans, apes, monkeys, primates, or hominoids?

  1. Sam C

    Using paraphyletic terms (that is, group names that denote what is left of the group once a subset has been removed) is a Very Bad Idea that hangs on in science, but it need not hang on in folk usage.

    I’m not sure whether you’ve lost or gained a negative, but I don’t have a strong objection to the occasional use of paraphyletic groups either in biology or less formal circumstances where appropriate. I think it’s quite OK to be interested in “reptiles” or “gram negative bacteria” even if a cladist can’t understand the terms.

    It’s probably useful occasionally to talk about freshwater fish or flightless birds. Not everything is always about clades. Depends what one wants to talk about.

    Linguistically we will often use a term to indicate a stereotype, so if someone says “ape” most of us would automatically think of a hairy animal swinging in the trees, not a hairless one tapping on a keyboard.

    Anyway, when somebody says “humans are/aren’t apes”, they are not usually making a taxonomic statement, their point is usually “our species is amazingly similar to and/or closely related to these other species, and therefore we should be nice to them”. Language is not all about logical propositions. In fact it rarely is. It’s about persuasion.

    • Sure, lots of language deals with paraphyletic, and even privative, groups. Politics, culture and so on are full of that sort of term. But when you are talking about natural groups, it helps to be dealing with natural groups. “Invertebrate” is not a natural group, but while nobody minds the term being used to name departments, if you strive to understand, and to educate others to understand, the natural world, that term is meaningless (are bacteria invertebrates? Protozoans?).

      The question is not “do ordinary folk use terms like ‘ape’ and ‘human’ carelessly and impressionistically?” because we already know they do. The question is “If we use language about taxonomic groups carefully, how are apes and humans related?” and the answer is “Humans are apes”.

      • Craig Wuthrich

        Surely you’re not actually saying that it’s never useful to talk about fish or monkeys or non-hominin hominoids? I don’t understand why it’s hard to believe that subsets of monophyletic groups are very often useful in science.

  2. There is no fact of the matter in such question. This is one of those cases where a different issue is masquerading as a question of fact.

    Most theists hold that humans are special and not animals. For that matter, quite a few non-theists take the same view. Even if they did not explicitly say it, that is probably what the Washington Times was implicitly arguing. And that’s what Jerry Coyne is almost certainly arguing against, although he did not explicitly say that, though he did note the religious connections of the Times with the Moonies.

    This is a cultural issue, not a factual issue. And there are disagreements between subcultures.

    The real Washington Times point: Atheists, such as Dawkins, are stupid and ignorant for not recognizing that humans are special.

    The real Coyne argument: Theists are stupid and ignorant for not recognizing that humans are not special.

    Me: I try to stay out of these silly polemics.

  3. Great post! If you haven’t read it already, I’d suggest Eco’s book “Kant and the Platypus: Essays on Language and Cognition.” He makes some nuanced and potent arguments about differences between taxonomy and everyday catigorization.

  4. In fact, unless I’m mistaken, “ape” and “monkey” originally meant the same thing: any non-human simian. (“Affe” in German still has this meaning.) It was primatologists who made the distinction in the first place! And all you have to do is go to a zoo to see that the common folk have yet to follow their lead even here. (*pointing at gorilla* Look at the big monkey!)

  5. Wikipedia says: “A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits.” Humans are not fish!

  6. All of the anthropologists I know colloquially use the term “apes” when referring to hominoids, a group that includes gibbons, orangs, gorillas, chimps and humans. I do this too.

    I don’t understand why John Hawks says that chimps, gorillas, orangs, and gibbons, all of which are hominoids, are “apes” but that humans, which are also hominoids, are not “apes.”

    If humans, chimps, gorillas, orangs, and gibbons are all hominoids, why would he call four of them “apes” but treat humans specially by calling them not apes? I don’t understand his argument or his point.

  7. Clear, as usual and … despite what Canadian biochemists might say … useful philosophy.

  8. “Apes” may not be a taxonomic name (whereas “Hominoidea” is), and so one could argue that it doesn’t much matter how it is used. However, there is another term that is used in similar fashion that does also have a taxonomic version: “animal” in common usage, meaning animals (or, more often, vertebrates or even just mammals) other than humans, and the kingdom Animalia. Here, the use of “animal” is taxonomically incorrect.

    But the larger point, I think, is what paraphyletic terms like “ape” and “animal” imply — namely that humans are separate from other species. Fixing that misconception is important, and pointing out that “either there is no such thing as an ape, or we are apes — take your pick” helps in that regard.

    So, I am with you (and Larry Moran, and Jerry Coyne, and Richard Dawkins) that we *are* apes, or else that we need to stop using the term “ape” in reference to a supposed biological assemblage.

  9. I have a dinosaur-mad 4yo daughter, so this is a matter of current interest for me. I’ve gone straight for “birds are the last of the dinosaurs”, as she keeps grabbing recent dinosaur picture books that show them with feathers and looking pretty darned birdlike.

    I note that the Wikipedia article on dinosaurs has also given up and now talks about dinosaurs in the present tense. I give it another ten years until “birds are dinosaurs” is as much in popular culture as “humans are apes” is.

    The sparrow with teeth on the Wikipedia “Evolution of birds” article is euwww.

  10. The term “dinosaur” has a scientific origin and was precisely connected to a taxon (Dinosauria) from its beginning. It’s “science’s property”. Thus, it’s scientists who decide which animals are dinosaurs and which ones are excluded. When somebody says: “Look that mammoth, a dinosaur!”, or “A chicken can’t be a dinosaur”, you have the “right” to correct him because there is a scientific definition (well, more than one…) of the dinosaur group.

    But ape is not a science-born term. It’s an ancient common word and it’s meaning doesn’t have to obey the rules of modern taxonomy and scientific nomenclature. Like many words about animals or plants, it doesn’t need to be conected to a specific valid taxon / clade. You don’t have the “right” to force humans into the meaning of “ape”. You can’t say Science tells us that “humans are apes”, or that Apes = Hominoidea. These claims are simply false. Of course you have the right to join a campaign for promoting a new meaning for the word “ape”, for whatever reason you consider desirable (to fight anthropocentrism, to promote ape rights, etc). Others would join or not. I am not joining.

  11. Jeb

    the Ape, “is a monstrous beast, but nevertheless one that is representative of human nature, and susceptible to training.”

    An old one from the “oratorum simia” vaults. The statement is a conclusion to a dispute over etymology rather than taxonomy.

    But Ape or Latin simius/ simias has been used in rhetoric since classical times and I don’t see why it should be excluded from such a role now or why it should be surprising that biologists inflect the word in a particular manner to make a particular point.

    Ape can also refer to abstractions or objects that assume the appearance of being something they are not, if you are inclined to inflect differently.

  12. Jeb

    “simia naturae” (lit. ape of nature) was used to complement an artists skill in representing the natural world in painting and sculpture. The later English word ape reflects perfectly the original metaphorical use in Latin. Ape seems to me a perfectly fitting term for biology to use as a metaphor.

  13. Rune C. Olwen

    So I was right.
    Reading John Hawks, I got the feeling “That is just like the old nonsense at school” and as I started to find out about atheism as a grownup, I discovered that Linneaeus lived during the witchburning time in Sweden and, if he didn´t make humans something special, he faced the risk of being burned on the stake just like a woman !
    But the reason why anyone, in the 1970s or nowadays, would repeat/defend that nomenclature mistake has been beyond me, and still is.
    Glad to be an ape and a fish also.

    • John S. Wilkins

      Linnaeus actually did include humans and apes together, and was chastised by a Lutheran bishop for doing so.

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  15. I’ll resist the temptation to call you a cladofascist. There is a very excellent little book entitled Naming Nature: The Clash Between Instinct and Science by Carol Yoon. Ms. Yoon, I would guess, would take issue with You, Dawkins and Wikipedia, and agree with the anthropologist. Our ancestors have been naming the natural world for so long, our once still evolving brain hard-wired some broad categories into us. Folk taxonomy predates systematics by millions of years. Most people don’t think humans are apes, or mammals are fish, because it’s doesn’t fit our ancient classification scheme ingrained in our 60,000 year old brain architecture. It is futile to attempt to change that. Do as Linnaeus did and invent a new vocabulary.

  16. We are great apes who ought to support the Great Ape project to give more protections to our kinfolk! Are we the third chimp after the chimpanzees and the bonobos? That’s the real question!
    Is florsiensis a homo or an earlier ape? Denisovans and Neanderthals are our fellow great apes.
    Duane Gish is an atavism! Is he a homo heidelburgensis or an antessor ?

  17. What do the religious liberals think about our being apes?
    They’re as potty as the others. Prof. Irwin Corey makes more sense!
    Lamberth’s Googe:] the atelic/ teleonomic argument argues that as science finds no divine intent behind natural phenomena, then to allege nevertheless that intent contradicts instead of complementing science.
    Theistic evolution then is just an oxy-moronic obfuscation!

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