Last week I wrote a post highlighting a silly piece by Vlasko Kohlmayer in the Washington Times denying that Richard Dawkins (or any human) was an ape. If you construe apes according to the definition I used—i.e., “Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea”—then, yes, we’re all apes, along with gorillas, orangutans, gibbons, chimps, and bonobos.
Anthropologist John Hawks objected, arguing that humans, though nested within the monophyletic groups above, formed their own clade, and that the word “ape” isn’t a precise taxonomic term, but a term of folk taxonomy:
“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.
I didn’t quite get this, because I was using “ape” in the way defined above: as a truly monophyletic group. Hawks doesn’t allow comment on his website, so there was no discussion.
On his website Evolving Thoughts, the philosopher of science John Wilkins took issue with Hawks, and agreed with me that humans are apes, summarizing the anti-ape argument and then refuting it with a simple diagram that shows us nested within the Hominoidea along with other apes:
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.
Here’s a diagram showing humans nested within the monophyletic group Hominoidea. The red bit includes the other apes:
He then explains why he thinks we’re 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.
Here’s a phylogeny of primates. Note that the “ape” group is monophyletic if it is construed to include humans. Note, though, that “monkeys” do not form a monophyletic group, because Old World monkey are more closely related to the apes than they are to New World monkeys. In other words, the group “monkeys” does not include all the descendants of a common ancestor; it is what’s known as a paraphyletic group. But construing things broadly, we could consider humans and apes as monkeys, just as we see humans as apes.
Finally, Brian Switek weighed in today on the Coyne/Wilkins side (I must say, Wilkins hasn’t always agreed with me!) in a post at Laelaps, “I’m an ape, and I’m also a fish.” What he means by being a “fish” means that humans are also nested in the monophyletic group that includes all the descendants of our fishy ancestors:
And the words we choose depend upon how specific we wish to be. In an evolutionary context, I am simultaneously an ape, a monkey, a primate, a mammal, a therapsid, a synapsid, an amniote, a tetrapod, and, to pick an arbitrary stopping point that suits this post’s purpose, a fish. You are a fish, too. Now, I typically don’t come home from an afternoon walk and tell my wife “There were so many fish walking around the park. Everyone’s out today” – such a statement would make it sound as if I had slipped into a Ray Troll painting – but, in an evolutionary sense, it still would have been true. Among other things, we’re fish. The term isn’t terribly specific, but it’s not inaccurate, either, as a newly-announced cousin of ours demonstrates. . .
I don’t expect the idea that we are fish to pick up much popular currency. The everyday, paraphyletic meaning of the term is entrenched, and I don’t expect anyone to refer to the salmon in their sushi as a “non-tetrapodomorph fish.” But the idea is still a useful one as we explore our relationship to the rest of life on earth. After all, we share a common ancestry with every other living thing on the planet, and, for a time, our ancestors and kin were snake-like fish with thick fins supported by stacks of bone. The way those fish swam, and walked, through prehistoric seas formed the foundation for the flowering of vertebrate evolution on land, including the later origin of a lonely species of upright ape obsessed with its own beginnings.
Yep, we’re apes. I don’t know what Hawks is on about, really, since apes are a monophyletic group, even if not a formal category. But Hominoidea is a formal category, and includes not just us, but everything that’s recognized as an ape by biologists.
In the end, this is a tempest in a teapot, for what the misguided Kohlmayer meant was that we do not share a common ancestor with other apes. And that’s clearly wrong. But yes, we are apes, and mammals, and reptiles, and fish, just as birds are dinosaurs. In the end, all that’s important is that we recognize where we fit in on the tree of life.