Get your own Free Home PageFROM: Ernest W McCracken, INTERNET:andrew103@juno.com DATE: 8/4/97 12:34 AM Re: Musings, mtDNA mtDNA and the Disappearance of Pheno-/Genotypes When public discussion of the mtDNA-based view of human development was originally introduced, the first thought to come to mind was, "What happened to all the other lines of mtDNA?" Scenario: At one time all the women on Earth were killed off, leaving only one to pass her mtDNA down to us . This is a ludicrous notion at best. Researchers quickly allayed our alarm by noting that most likely these lines petered out through attrition. They drew an analogy to the impersistence of family names. Where family names are passed down exclusively through the father, some family names will naturally die out over a period of time. This happens because couples who have only girl children cannot perpetuate the family name. Over a period of centuries, many family names disappear through this sort of attrition. Family names in Korea are a glaring example of this. It is an ongoing joke among non-Koreans that everybody in Korea is named either Kim or Lee. The actuality is not far removed from the joke. There are probably not many more than ten family names that account for 95% of Korean people.* For many centuries, Korea was a closed society that did not allow immigration. Since the family names were passed down through patrilineal descent and there was little or no influx of foreign names, the number of family names dwindled through just the type of attrition described above. By the same token, mtDNA variations must have dwindled in number over the millenia, until, some 200-300 thousand years ago, there was only one type left. This is not my idea, but rather the suggestion of the researchers who originally proposed the concept of a common female ancestor. Now, finding that Neandertal mtDNA differs from ours, some scholars contend that our ancestors killed off the Neandertals and that they are a separate species which could not possibly have interbred with our ancestors. By that line of reasoning, we would have to conclude that our ancestors also killed off all the other lines of Cro-Magnon (CM) mtDNA, also. A grim picture indeed! Meanwhile, there are other possible scenarios to consider. After all, if all other non-Neandertal lines of mtDNA were extinguished through attrition, we might want to entertain the possibility that the same could have happened to Neandertal mtDNA. This would eliminate the necessity of constructing a speculative fantasy in which the CM commit genocide on the Neandertal peoples. Traits which resemble Neandertal phenotypes can be commonly observed in modern humans. However, they are less conspicuous among certain groups. Also, some groups display different such traits. Enlarged brow ridges are seen often among Caucasians, Africans, and especially Australian Aborigines, but they are notably lacking among Orientals. Excess body hair is a noticeably Caucasian feature. Flattened noses with flared nostrils are most common among Africans. Prognathism is prolific among Orientals. Women are the broadest population found with predominance of modern, gracile features, and this crosscuts all races. This brings us to an idea that I believe is worth considering: that the first CM was born from Neandertal parents and passed down dominant genes for CM traits. This phenotype was valued by our ancestors and we have bred ourselves since then for gracility. The above is only one of the many possible ways in which attrition can account for the disappearance of the Neandertal phenotype. Remember, only the Classic Neandertal phenotype differs markedly from modern humans. The rest, given a modern business suit, a shave, and a haircut, could walk down the streets of a modern city without undue notice. We are talking about differences that are no more varient than the differences between races-- or individuals --among modern human populations. In short, the description of human descent cannot be determined by one factor alone, no matter how respectable it may appear by means of lab coats and test tubes. The scenario of CM killing off Neandertals in a kind of pleistoscenic genocide may be more exciting than the tame concept of attrition, but that does not validate it. Archaeology and paleontology have always proceeded by cross-referencing data from different disciplines and different studies. At this point, it seems to me that the principle of parsimony applies and Occam's razor slices in favor of attrition. But of course, it all remains to be seen in the revealing light of data yet-to-come. * Kim, Lee, Jung, Jang, Im, Jo, Suh, Song, Bae, Park, Mun
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