To: Jack Brannan Msg #358, 940320 11:%:00 Subject: HOMO SAPEINS ERECTUS: NOT On 14 Mar 94

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From: Phil Nicholls To: Jack Brannan Msg #358, 94-03-20 11:%:00 Subject: HOMO SAPEINS ERECTUS: NOT On 14 Mar 94 11:52am, Jack Brannan wrote to Phil Nicholls: JB> Can you tell us just what is the distinction between Homo erectus JB> and Homo sapiens? I could tell you but I don't know how meaningful any list will be. As a matter of fact, I am writing a paper on this subject for a seminar I am taking now on the origin of Homo sapiens. Paleontologists and biologists both use a morphological species concept operationally. This means that a species is defined on the basis of morphological variation and not on the basis of observed reproductive discontinuity. It is observed by both paleontologists and biologists that the morphological differences between species are the result of reproductive isolation. In keeping with this assumption, species are defined on the basis of autoapomorphic traits. This means you look for traits that are unique when taken together. Such autapomorphies can only arise from reproductive isolation. Phillip Rightmire, who may well be the foremost authority on Homo erectus today, lists the following as diagnostic of Homo erectus: 1) brow is thickened and continuous and there is a flat supratoral shelf behind. [some Homo sapiens have brow ridges but they are not continuous and there is no shelf behind the brow] 2) frontal bone exhibits midline (saggital) keeling 3) there is an angular torus at the posteroinferior corner of the parietal bone. [can't really explain this one without a skull to point it out] 4) the occipital squama is wide and sharply angled [it is rounded in Homo sapiens and narrow] 5) the morphology of the transverse torus of the occipital is distinctive [again you would have to see this] Well, I can go on, but I think you can see that unless you are very familar with the form of the skull and it's anatomical features it is difficult to follow. JB> I find it very odd that these remains found in Australia can be JB> moved so easily from one classification to another. The Kow Swamp materials were never really classified as Homo erectus, but the problem can sometimes be that when you only have a fragment of a skull and the bones appear thicker and more robust you can see similarity to Homo erectus. JB> I know that there are about 10-12 things that paleontologists look JB> at, but it seems that these same features can be found in varying JB> individuals today. As far as I have been able to find there is no JB> feature that is unequivocal. There are no individuals today that have brow ridges that are continuous and the very distinctive shelf behind the brow ridge that we see in Homo erectus. There is no modern human that shows the saggital keeling. Look at the skulls from the back and notice the pentagonal shape. I defy you to find that on any modern human. Let's talk cranial capacity for a minute. Yes, the range of cranial capacity does overlap. Look at the mean, though. Look at the standard deviation. The AVERAGE cranial capacity for Homo erectus is about 980 cc. That's the AVERAGE. Averages in human populations today range from 1150 to 1550 (Australian and Eskimo respectively). I suggest anyone interest in Homo erectus should see Rightmire's book. Philip Nicholls ... Writing to Washington won't help -- he's dead! Department of Anthropology * Evaluation copy of Silver Xpress. Day # 12 * Silver Xpress V4.00 --- COMNET v1.32k/QWK * Origin: COMNET Headquarters [Albany, NY] (1:267/113) From: Phil Nicholls To: All Msg #359, 94-03-20 11:%:00 Subject: HOMO ERECTUS Mark Johnson's recent message about Homo sapiens/Homo erectus came at a time when I am preparing a paper on the species problem in paleoanthropology. As it turns out, Mark was not entirely off base when he suggested that Homo erectus should be re-classified as Homo sapiens. The question of "what if anything is a species" is still a big one in biology. The biological species concept (BSC) which has been widely accepted as a theoretical model is not operational in most cases. Biologists still use a morphological species concept. If speciation is the result of reproductive isolation, specifically, as Mayr insists, geographical isolation, morphological diversity is a RESULT of speciation and not a cause of speciation. Speciation can occur without any initial morphological variation at all. Given this, and given the fact that many morphological traits used to identify living species are soft-tissue traits, a morphological species concept in paleontology will lead to an underestimation in the number of species present in the fossil record. For the concept of species to be meaningful in paleontology (as opposed to arbitrary) it must seek to identify differences that are the result of historical events that lead to the isolation of populations. This means that the only traits that can be used to identify species are unshared and derived. In the jargon of cladistics, these are called autapomorphic traits. Autapomorphic traits can reasonably only arise as a result of cladogenesis. IF the multiregional hypothesis is correct, then from Homo habilis to anatomically modern Homo sapiens there has been a single, unbranched lineage, which should be recognized as a single polytypic species, Homo sapiens (anagenesis). IF the multiregional hypothesis is not correct, then there must be more species of Homo in the fossil record than we currently recognize. This has been suggested by Benard Wood and Ian Tattersall in separate articles. This means that many fossils currently recognized as Homo erectus will be placed into new taxa. Which answer is reasonable? If we use speciation as observed in non- human primates, then we must reject the multi-regional model. If, on the otherhand, we look at modern Homo sapiens, and acknowledge that we are a single polytypic species, we know that the non-human primate model does not apply today or in our recent history. The question we need to address is HOW recently does this model become applicable to hominids. * Evaluation copy of Silver Xpress. Day # 12 * Silver Xpress V4.00 --- COMNET v1.32k/QWK * Origin: COMNET Headquarters [Albany, NY] (1:267/113)


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