The common ancestor? At long last?

[CDarwin]

http://www.pnas.org/cgi/content/abstract/0706190104v1

 

Extant African great apes and humans are thought to have diverged from each other in the Late Miocene. However, few hominoid fossils are known from Africa during this period. Here we describe a new genus of great ape (Nakalipithecus nakayamai gen. et sp. nov.) recently discovered from the early Late Miocene of Nakali, Kenya. The new genus resembles Ouranopithecus macedoniensis (9.6–8.7 Ma, Greece) in size and some features but retains less specialized characters, such as less inflated cusps and better-developed cingula on cheek teeth, and it was recovered from a slightly older age (9.9–9.8 Ma). Although the affinity of Ouranopithecus to the extant African apes and humans has often been inferred, the former is known only from southeastern Europe. The discovery of N. nakayamai in East Africa, therefore, provides new evidence on the origins of African great apes and humans. N. nakayamai could be close to the last common ancestor of the extant African apes and humans. In addition, the associated primate fauna from Nakali shows that hominoids and other non-cercopithecoid catarrhines retained higher diversity into the early Late Miocene in East Africa than previously recognized.

 

Now this wouldn't be the common ancestor of humans and chimpanzees; that was a few million years off, but the common ancestor of all the African apes, which is just as fascinating. This would be the primitive layout from which the human, gorilla, and chimpanzee conditions are derived. So, any thoughts on its implications? Its validity? I can't actually access the article, so I can't say much. Looks pretty promising, though. Ouranopithecus is fairly well known from Greece, so if this is a close relative, we could have an unprecedented look at the starting point of our own unique lineage.

[Mr Skeptic]

Yay! The Holy Grail has been found! Again!

[CDarwin]

I don't think you're supposed to use those outside of GD, but then again I don't think you're supposed to make useless condescending comments either. But onto my actual post:

 

I got a chance to read the article, and this is my distillation:

 

If Nakalipithecus is the common ancestor of the African apes (and Ouranopithecus, which was a later genus than Nakalipithecus), then these would be the lineage's most noteworthy derived features (or at least the ones that I caught): A prominent inferior transverse torus (also known as the simian shelf, a bony shelf in the mandibles of the living African apes lost in hominids); low but broad central incisors with narrower lateral incisors; large, gorillia-esque size; relatively squat canines, which the modern African apes possess relative to some Miocene apes and hominids take to a much higher degree; and a large first molar compared to the second molar.

 

From the closely related but slightly more recent Ouranopithecus we can infer: A supra-orbital torus (as all modern apes and Sahelanthropus possess), a broad space between the eyes, a broad nasal apeture, and sexual dimorphism.

 

The biggest problems I could see come from the hominid-like quality of Nakalipithecus's teeth. They are thick-enameled like hominds', and the lower premolars are broad and lack the honing facet that African apes have, and many early hominids show traces of.

 

The canine of Nakalipithecus has a prominent bump on the inside, however, that makes the tooth more premolariform. Perhaps this indicates a heavy emphasis on chewing which could explain a secondarily derived thick enamal and broad premolars, and the real common ancestors is still a few years older and more primitive.

 

What all of this does mostly-definitavely tell us is that the last common ancestor of all the African apes probably really did originate in Africa, and didn't migrate from another continent.

[lucaspa]

Toumai and Ardipethecus are close to the common ancestor of humans and chimps. Mr. Skeptic, you can derive this by noting the arguments over whether the species are on the human or chimpanzee side of the split!

 

Mr. Skeptic, the "holy grail" of transitions between apes and humans has been found so many times that it is not an issue anymore. It is only an "issue" for creationists, who keep trying to deny that the transitionals exist. This particular paper is trying to go back and find the common ancestor for ALL the great apes. It predates the split leading to the hominid lineage by 2-3 million years. If it is not the common ancestor, then it is a close relative of the common ancestor.

[Mr Skeptic]

Mr. Skeptic, the "holy grail" of transitions between apes and humans has been found so many times that it is not an issue anymore. It is only an "issue" for creationists, who keep trying to deny that the transitionals exist.

 

It is also an issue with the militant ateists, and anyone else who likes to rub science in the faces of the creationists. I'd go so far as to say that most people who are want "The Missing Link" to be found are want it for this rather silly reason. As opposed to wanting to understand our biology and psychology better, or simply wanting to get the species tree completed, which would be much better reasons. Hence why I said "Yay!", put exclamation points everywhere, used the "Jesus" bubble, and was dripping with sarcasm.

 

Mush of the less educated public seems to think there is this one missing link, "The Missing Link", hence "the Holy Grail". A good parallel because of the number of people searching for both these items. Makes a much better headline to find the missing link than just a missing link, so the evil journalists perpetuate that myth. I suppose it is somewhat accurate because there is only one common ancestor between two species. Lots of links have been found, and lots have made headlines as The Missing Link , hence why I said "Again."

 

No one appreciates my brilliant satire

 

It also expresses my opinion on this subject in a very succinct manner, which is why I put it here rather than elsewhere. I'd also note that they aren't even certain what they found, "N. nakayamai could be close to the last common ancestor of the extant African apes and humans.", but it is The Missing Link anyway.

[vampares]

Lowest common dominator, can't be no one, can't be in a tree. hmm. You know if there is one thing I hate it's factions.

[CDarwin]

It also expresses my opinion on this subject in a very succinct manner, which is why I put it here rather than elsewhere. I'd also note that they aren't even certain what they found, "N. nakayamai could be close to the last common ancestor of the extant African apes and humans.", but it is The Missing Link anyway.

 

Well obviously, but the point's pedantic. The important thing isn't the fossil itself, it's the information the fossil contains. When Robert Broom fell to his knees in honor of "the ancestor" when the first saw the Taung skull, it was obvious to him that that particular individual could be our actual ancestor; it was only a child when it died.

 

Nakalipithecus almost certainly isn't the *actual* common ancestor of all the African apes. But it's close, and it tells us things. For one, the common ancestor stands a good chance of being gorilla-sized.

[lucaspa]

It is also an issue with the militant ateists, and anyone else who likes to rub science in the faces of the creationists. I'd go so far as to say that most people who are want "The Missing Link" to be found are want it for this rather silly reason. As opposed to wanting to understand our biology and psychology better, or simply wanting to get the species tree completed, which would be much better reasons.

 

Perhaps I wasn't clear. There is no the Missing Link. Instead, there are dozens of "missing links" linking hominid species in a line back from H. sapiens to the common ancestor with chimpanzees. There are transitional individuals taking our ancestry back thru 2 species to a third: A. afarensis.

 

The reason people looked for intermediates from the common ancestor was exactly because they wanted to understand our biology and psychology better. Huxley gave a series of lectures and papers in the 1860s describing the similarities between the great apes and humans. Darwin in Descent of Man noted psychological similarities, and people have continued that work ever since. All this supports the hypothesis that we and the great apes evolved from a common ancestor. Therefore looking for fossils of intermediate species is part of testing that hypothesis. If the hypothesis is incorrect, then no intermediate species would be found.

 

Since many transitionals ("missing links") have been found, the search now is more akin to geneology: exactly what species and where was the common ancestor? For H. sapiens, did all humans arise from a single population in Africa or was it a blending of many populations around the world (Mutiregional). Genetic data refute Multiregional.

 

Mush of the less educated public seems to think there is this one missing link, "The Missing Link", hence "the Holy Grail".

 

That's their problem. In this forum we are here to discuss the science, aren't we? Not project onto science the misconceptions of the public but to find out what the data really is. Right?

 

Makes a much better headline to find the missing link than just a missing link, so the evil journalists perpetuate that myth.

 

Then that is a problem of journalism. If you want to satire journalism, then you need to be more specific. Otherwise, we aren't going to appreciate the satire, because it looks like you are denying science and the data.

 

I suppose it is somewhat accurate because there is only one common ancestor between two species.

 

It goes beyond that. There is also only one common ancestor between lineages. Thus there is one species that is the common ancestor of all the great apes -- including us. There is also one species that is the common ancestor of all tetrapods (birds, dinos, sauropsids, amphibians, and mammals).

 

The issue is specifically which "missing link" we are talking about. Tiitikalek (sp) is a "missing link" in the chain between fish and amphibians.

This particular article was correct in limiting this particular "missing link" to the common ancestor all great apes, not a common ancestor of chimps and humans.

 

I'd also note that they aren't even certain what they found, "N. nakayamai could be close to the last common ancestor of the extant African apes and humans.", but it is The Missing Link anyway.

 

See above, N. nakayamai is a "missing link" in THIS particular area. I think the problem is that you have the misconception that there is only one "missing link". As we look at lineages and the fossil record, there have been many "missing" links between lineages -- different links depending on which lineage we are looking at.