Humans and chimpanzees have a common ancestor which was an ape.
All modern apes have a common ancestor (presumably also an ape, but that’s not germane to my question). The Apes are a clade.
Old-world monkeys are more closely related to apes than they are to new world monkeys (The Monkeys are not a clade).
Now, I have often heard it said that apes are not descended from monkeys. IIRC Richard Dawkins says it in The Ancestor’s Tale (sorry. no cite. Don’t have copy handy).
… it seems trivially true that we are descended from monkeys unless new- and old- world monkeys evolved independently (which they didn’t).
So, my question:
Are they people (usually smart, knowledgable biologist-types like Dawkins) who make the claim “we are not descended from monkeys” making some important point that I am missing? If so, what is it?
If the term “monkey” is to have any natural meaning, apes are monkeys–they are a particular branch of the old world monkeys. Then new world monkeys, old-world monkeys, and the type of old world monkeys called apes are all monkeys. And they are contrasted to other primates that aren’t monkeys–like lemurs and tarsiers.
So, humans are a particular kind of ape, apes are a particular kind of monkey, monkeys are a particular kind of primate, primates are a particular kind of mammal, mammals are a particular kind of tetrapod, and tetrapods are a particular kind of vertebrate.
The “apes aren’t monkeys!” argument is wrongheaded. It can only be true if we argue that cladistically speaking there’s no such thing as a monkey.
For instance, cladistically speaking, there’s no such thing as a zebra. Some kinds of equids have stripes, and some don’t, and we can call the kinds of equids that have stripes “zebras” but there are several species of zebras that are more closely related to unstriped horses than they are to Grevy’s Zebra (Grévy's zebra - Wikipedia). Therefore, unless we declare that domestic horses are zebras, then zebra is an incoherent classification, and is merely a descriptive term, not a phylogenetic term.
“Fish” is another such term–if we declare that both lobe finned and ray finned fish are fish, then tetrapods are fish too. Since that seems silly, we tend to declare that “fish” is just a descriptive term for vertebrates that live in the water. And even some creatures that aren’t vertebrates are popularly called “fish”. So “fish” isn’t a rigorous cladistic term, and rescuing it as a cladistic term would cause more confusion that it would solve.
But “monkey” is different. Apes are a kind of monkey, and it does no violence to the concept of “monkey” to include apes as a subset of monkeys. Therefore, “monkey” is a perfect acceptable cladistic word.
I expect that smart people are refuting Creationists, who confuse evolution with abiogenesis and claim ‘evolution states man is descended from (modern) monkeys’.
Remember it’s less than 75 years since the ‘Scopes Monkey Trial’ (where evolution teaching was banned in Tenessee schools).
To extend a little on what glee said, it’s usually to make the point that we are not descended from any modern monkey (or ape). This is a bit moot, however, since if the ancestral form were alive today, it would in fact be considered a monkey.
As Lemur866 explained above, cladistically speaking it is true. The “main ancestor” you refer to would have been a monkey, since it gave rise to “monkeys” in both lineages (New World and Old World). Since apes are nested within monkeys, they are also monkeys.
Of course, we get into problems trying to apply English names to clades, but cladisitically speaking apes are descended from monkeys (and hence are a kind of monkey).
If we can say that birds are a kind of dinosaur, and humans are a kind of ape, then it is perfectly plain that apes are a kind of monkey. A particular atypical branch of the monkey family tree of course, but still monkeys. Just like humans are atypical apes and birds are atypical dinosaurs. But to insist that birds aren’t dinosaurs and humans aren’t apes and apes aren’t monkeys is merely to insist that no such scientific categories exist.
If birds aren’t dinosaurs, then we might as well call any large extinct critter a dinosaur, like in those packs of plastic toys.
Likewise, if apes aren’t monkeys then what the heck IS a monkey?
No. One one branch we have “new world monkeys”. On the other branch we have “old world monkeys” and “apes”. Therefore, any definition of “monkey” that includes both new world and old world monkeys must logically also include apes.
Not quite true - the teaching of evolution in Tennessee was banned under the Butler Act. The Scopes Trial was a prosecution of Scopes for breaking that law. He was found guilty, but the ban already existed.
Are you speaking purely from a genetic-similarity standpoint? Because birds have feathers, and dinosaurs (mostly) didn’t.
I have no idea whether dinosaurs mated using the squished-cloacae method, although I’d guess not, which would be another fairly significant difference.
Well the diagram is incorrect isn’t it? Is it coincidence that a Lemur is posting here? From Lemurs, proto-Monkeys; from proto-Monkeys modern Monkeys and proto-Apes; from proto-Apes, modern Apes and Hominids; from Hominids, Humans of various species all but one (or one sub-species of Homo Sapiens) now extinct.
Recent questions about whether humans may in fact be closer to Orang-Utans than Chimpanzees and debate still unsettled as to whether to class Neanderthal as Species *Homo Neanderthalensis[/i ]or Subspecies Homo Sapiens Neanderthalensis
Neither of these points is particularly relevant to the question of whether birds are dinosaurs. There are quite a few skeletal characters establishing that birds are a subset of dinosaurs.
Woops! I put them in on a guess because I like them The rest should be correct though. The essential point is that the simple Monkey-Ape-Human is correct up to a point but it makes it look like a line where modern monkeys became apes and modern apes became human more than that a common ancestor split into Monkeys (with tails) and a tailless common ancestor that split into Apes and Hominids, which then split into various early human species.
It’s a week or two ago that I came across (possibly in New Scientist online) revival of an old genealogy that puts us closer to Orangs than Chimps despite having more DNA in common with the latter. It depends how ancient the DNA is and how it is linked up. I don’t remember it in detail but the general idea is that a species might develop rapid specialist DNA changes that differentiate it from another close to it that is left with more of the ancestral DNA common to the whole group and that may have happened to Orangs because their environment is so specialised. In effect, they went back up the trees and we stayed out (or went in the water according to another theory)
I dislike this kind of reasoning, because it’s playing to a fundamental misunderstanding of evolution/common descent. We are mammals and are descended from mammals in just the same way that we are (descended from) monkeys.
But mainly I don’t understand why monkeys are getting dissed.
I don’t have a copy handy either, but I’m guessing one of two things:
(1) Dawkins said apes are not descended from <i>old-world</i> monkeys (in agreement with your diagram), or
(2) he’s of the opinion that old-world monkeys and new-world monkeys are not closely related enough to form a true clade. I think there is debate (sorry, no cites) as to whether the common ancestor of old and new-world monkeys was something we would call a “monkey”.
The rest should be correct though. The essential point is that the simple Monkey-Ape-Human is correct up to a point but it makes it look like a line where modern monkeys became apes and modern apes became human more than that a common ancestor split into Monkeys (with tails) and a tailless common ancestor that split into Apes and Hominids, which then split into various early human species.