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Monday, June 11, 2012

Archaic Admixture or Deep African Substructure on the Deinekes Blog.

Dienekes Blog I wanted to post this as a reply on Dienekes blog but it doesn't allow for enough space. Some people REALLY want OoA to be true despite the death bells. This is from a paper quoted in the blog linked to above: "There is a broad agreement that the contribution of archaic Homo populations to the modern gene pool, if any, must have been very limited [33], [34]. Different lines of evidence concur to suggest that the dispersal of anatomically modern humans from Africa was accompanied by repeated founder effects [35]–[38]. If these founder effects were drastic, most or all gene genealogies should actually be shallow, and hence the occurrence of ancient splits would imply some degree of introgression from archaic human forms. However, different consequences would be expected if only mild founder effects occurred when anatomically modern humans moved out of Africa. Under these conditions, gene trees would have a strong random component, and a certain fraction thereof, even in the absence of selection, would show two highly divergent major lineages [39]. The likelihood of finding gene genealogies with a very old common ancestor and very differentiated lineages would be even higher if the source African population was subdivided and structured genetically before dispersal, which is what most studies clearly suggest [40]–[43]. These theoretical considerations are actually matched by consistent results in simulation studies [5], [34], [44] and by variation in neurocranial geometry, suggesting significant levels of geographic structure among early modern humans from Africa [6]." This is about the stupidest thing I've ever read by someone (presumably) with a college degree. Basically it's saying that people were more geographically/sexually isolated in Africa, then they came out and were less geographically/sexually isolated. In geneology we have thousands of examples of back-migrations into Africa...noteably by DE and CF y haplogroups and M and N mtdna haplogroups. Those, by the way, are the haplogroups which most scientists say probably evolved after any Out of Africa event, outside of Africa. They are also the haplogroups of people that have the most "neanderthal" alleles in their nuclear DNA, and the highest percentage of macrocephalin D. Of course if DE, FC, M, and N were isolated from each other in Africa, each with the same amount of archaic genes (which was significantly more than all the other Africans) before OoA,and a now extinct population was also isolated from every other population in Africa, and all those groups left Africa separately and then decided to blend which each other sometime after they got to Eurasia....then sure, you'd see these same results....as long as the population that had microcephalin D went extinct shortly after passing on the gene to one of the other OoA populations. The problem with the theory is that whether it all happened out of Africa you'd see these same results too, and we don't have to explain why populations would have isolated themselves inside Africa for 100,000 years, then gone out of Africa, and then decided not to isolate themselves from ANYBODY anymore, even coming into Africa to procreat. We don't have to explain how the one population in Africa managed to keep from passing micro D onto anyone else in Africa for 180,000 years, or how all of the other offspring of 180.000 year old mitochondrial eve negatively selected against this 990,000 year old gene...bnut then started selecting for it 37,000 years ago. Nor do we have to explain how the 70,000 year old offspring of mito eve (DE, CF, and M and N) kept archaic genes in their genome for 110,000 years when the older clades (A, B and the Ls) effectively selected them out. Also, neanderthal not having macro D tells us absolutely nothing. There are plenty of other hominids we could have gotten macro D from - homo erectus soloensis, homo lufuensis (who was making Upper Paleolithic tools 50 thousand years before us despite a grapefruit sized brain), the Red Deer Cave People, the Denisovans, and the "almost sapien sapients" who were anatomically modern modern but most likely out of our genome, such as Balangoda Man, the 109,000 year old AMHS recently found in South China, Mungo Man, and others. The shortest distance between two points is a straight line...unless of course you're deeply attached emotionally to the outdated concept of the Out of Africa model.
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