"I thought about it before I re-thought about it."
Posted on 06/19/2006 7:08:06 PM PDT by Marius3188
ANN ARBOR, Mich.—The earliest known hominid fossil, which dates to about 7 million years ago, is actually some kind of ape, according to an international team of researchers led by the University of Michigan. The finding, they say, suggests scientists should rethink whether we actually descended from apes resembling chimpanzees, which are considered our closest relatives.
U-M anthropologist Milford Wolpoff and colleagues examined images and the original paper published on the discovery of the Toumaï cranium (TM 266) or Sahelanthropus tchadensis, as well as a computer reconstruction of the skull. Two other colleagues were actually able to examine the skull, Wolpoff said, in addition to the images and the computer reconstruction.
The research team concluded that the cranium did not sit atop the spine but in front of it, indicating the creature walked on all fours like an ape. Hominids, he said, are distinguished from all other primates by walking upright. Hominids are everything on the line leading to humans after divergence with chimpanzees. Upright bipedalism is the single best way of identifying which fossils are hominids.
Researchers also examined the canine teeth and found that they were not clearly human or ape-like, but rather like most other canine fossils from the Miocene era.
"Whether or not it's a human ancestor is probably unimportant as far as the skull is concerned," Wolpoff said. "But it's very important in trying to understand where humans come from. It's the first relative we've had of the earliest hominid, or something related to it, but it's not a hominid at all."
Nor does the skull resemble a living chimpanzee—no fossil records of chimpanzees exist so it's impossible to compare to earlier descendents, Wolpff said. Genetic data puts the divergence of chimpanzees and humans at anywhere from 4 to 6 million years ago. Even though it's not a definite date, it makes it difficult to show a 7-million-year-old fossil is a hominid without overwhelming evidence, he said.
"The big message it sends us is our ancestors never looked like a chimpanzee," Wolpoff said. "This thing is clearly saying that chimpanzees are just as different from this ancestor as we are. They are just different in a different way."
Wolpoff said the skull could be a common ancestor of humans and living chimps.
"Now we have insight into what an early ape looked like, but we have no fossils of apes after it, so you can't tell clearly," he said.
Colleagues include John Hawks, Department of Anthropology of the University of Wisconsin, Madison; Brigitte Senut, Department Histoire de la Terre, Museum National d'Histoire Naturelle, Paleontology; Martin Pickford, chair of Paleoanthropologie et de Prehistoire, College de France; and James Ahern, Department of Anthropology, University of Wyoming, Laramie.
"Two people have seen it. We've all have seen pictures and read publications,"Wolpoff said. "It took us a long time to put this together because we wanted to make sure we were absolutely accurate."
Wolpoff expects that the paper, entitled "Ape or the Ape: Is the Toumai Cranium TM 266 a Hominid?" will be controversial. It was published Friday in a new online journal by the Paleoanthropology Society, http://www.paleoanthro.org/journal/contents.htm.
"I think some people are going to like it, and some people are going to hate it, but it will stimulate more discussion, which is important," Wolpoff said.
For information on Wolpoff, visit: http://www-personal.umich.edu/~wolpoff/.
For more on the Department of Anthropology at U-M, visit: http://www.lsa.umich.edu/anthro/.
Boo hoo.....
How does we KNOW where they were ALL living???
But... coyote IS a trickster!
Says volumes!!!
Sorry, wrong again. People who believe in Darwinian theory are NOT close minded. And, this does nothing to dispute ANYTHING about evolution. All it does is re-arrange the pieces a TINY bit. In fact, it should show you how evolutionists are willing to change theories and views based upon new evidence. As opposed to creationists - who eschew any and all changes IN SPITE of mounds of evidence.
"I thought about it before I re-thought about it."
(I use Macs, so I don't know a thing about most other folks' problems.)
There goes the thread!!!!
I told you!
Then, there are creationists and drug warriors....(sigh)
Or OLD evidence....
The ape interpretation could mean that Sahelanthropus was uniquely ancestral to a living ape, or that the species was an extinct related lineage that diverged before the hominids, or that it is close to or actually the last common ancestor of hominids and chimpanzees. If any of the alternative phylogenies is correct, the description of “ape” would be valid. The common ancestor of Homo and any ape species is traditionally and currently described as an ape.Did everyone catch Le Gros Clark in 1934 noting that "The Controversy" in real science was over in his day? And what the authors are saying is that tchadensis is not a "hominid" but an "ape" if it diverged to soon or is itself the last common ancestor.
That man is derived from a form which … can be properly called an ‘anthropoid ape’ is a statement which no longer admits doubt (Le Gros Clark, 1934).Today … we recognize … that the last common ancestor of apes and hominins was a great ape but not necessarily like any particular modern species (Ward, 2003, p. 75).
Another point which should emerge very clearly from the discussion in that link: it is very, very hard to tell a "hominid" from an "ape" in the late Miocene. Why in heck should that be?
Keith Miller explains it well:
The character states used to define higher taxa are determined retrospectively. That is, they are chosen based on a knowledge of the subsequent history of the lineages possessing those traits. They do not reflect the attainment of some objective higher level of morphologic innovation at the time of their appearance. Also, all the features subsequently identified with a particular higher taxon do not appear in a coordinated and simultaneous manner but as character mosaics within numerous closely-related species lineages, many of which are not included in the new higher taxon. In addition, as discussed above, the species associated with the origin and initial radiation of a new taxon are usually not very divergent in morphology. Were it not for the subsequent evolutionary history of the lineages, species spanning the transitions between families, orders, classes, and phyla would be placed in the same lower taxon (Fig. 3).Taxonomy, Transitional Forms, and the Fossil Record .Based on the above discussion, a transitional form is simply a fossil species that possesses a morphology intermediate between that of two others belonging to different higher taxa. Such transitional forms commonly possess a mixture of traits considered characteristic of these different higher taxa. They may also possess particular characters that are themselves in an intermediate state. During the time of origin of a new higher taxon, there are often many described species with transitional morphologies representing many independent lineages. It is usually very difficult if not impossible to determine which, if any, of the known transitional forms actually lay on the lineage directly ancestral to the new taxon. For this reason, taxonomists commonly have difficulty defining higher taxa, and assigning transitional fossil species to one or the other taxon. But, although the details may elude us, the patterns of evolutionary change are in many cases well recorded in the fossil record.
When you run evolutionary divergence backwards, you see convergence. The farther back you go, the more unlike things look like each other until you don't know what silly "created kind" bin to put things in. That's what evolution says you should see. That's what you do see.
No. Wolpoff is trying to tell you what he means here.
"Whether or not it's a human ancestor is probably unimportant as far as the skull is concerned," Wolpoff said. "But it's very important in trying to understand where humans come from. It's the first relative we've had of the earliest hominid, or something related to it, but it's not a hominid at all."You no doubt skipped that and zoomed in on this:
"The big message it sends us is our ancestors never looked like a chimpanzee," Wolpoff said. "This thing is clearly saying that chimpanzees are just as different from this ancestor as we are. They are just different in a different way."Even here, no doubt your mind seized that first, bolded sentence and discarded the rest. Lovely quote-mine material and I have no doubt Luddite idiots will be waving it around for decades to come.
Wolpoff is saying that some have underestimated how much the chimps have diverged from the last common ancestor. I've done this myself, apparently. There was no reason to suppose that the chimps have diverged all that much, but they apparently have. And, if they have, then fewer of the differences between Sahelanthropus and humans are the result of changes along the human line, etc. Looked at in THAT way, Sahelanthropus may be older than the LCA, or a side branch cousin of the LCA. It's still a clue to what was going on back then.
Sorry to pee on the campfire.
Keith Miller explains it well:
The character states used to define higher taxa are determined retrospectively. That is, they are chosen based on a knowledge of the subsequent history of the lineages possessing those traits. They do not reflect the attainment of some objective higher level of morphologic innovation at the time of their appearance. Also, all the features subsequently identified with a particular higher taxon do not appear in a coordinated and simultaneous manner but as character mosaics within numerous closely-related species lineages, many of which are not included in the new higher taxon. In addition, as discussed above, the species associated with the origin and initial radiation of a new taxon are usually not very divergent in morphology. Were it not for the subsequent evolutionary history of the lineages, species spanning the transitions between families, orders, classes, and phyla would be placed in the same lower taxon (Fig. 3).
This is a good point to remember, and as Graham Budd has pointed out, it helps explain why we look back at the Cambrian and have such a hard time classifying a lot of the organisms. Stem group organisms often do not fit comfortably into crown groups.
Yes, when we rain on your parade you always have the old fallback, "No one saw it anyway!"
Exactly. The Cambrian phyla show different body plans, but in each case they represent a very early stage of experimentation with the architecture. They're all rather small and simple compared to the variety of life in the same phyla now.
IOW, they look only recently diverged from each other. (That's using "recently" in the geological sense.)
Well, judging from your statement, you either didn't read the paper or didn't understand it. So which is it?
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