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Following Trails of the Cro-Magnon
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[QUOTE]Originally posted by The Explorer: [QB] [QUOTE]Originally posted by MindoverMatter718: Clyde since when did the San carry hg N? [/QUOTE]That question raises another point. First, reflecting back on Caramelli et al.'s findings: Understanding what is involved… From this link: http://www.pnas.org/cgi/content/full/100/11/6593 , we have: [i][b]Even the most stringent available criteria for validating ancient human DNA sequences DO NOT ALLOW ONE TO PROVE that the sequences determined are AUTHENTIC.[/b] Only if a sequence is [b]radically different[/b] from modern ones, as is the case for Neandertals, can one be relatively sure that no contamination has affected the results. Therefore, a certain degree of prudence is necessary before drawing any conclusions from this study. Still, none of the biochemical tests we carried out suggests that different sequences (namely the endogenous one plus some contaminating sequences) were amplified from the 23,000- and 25,000-year-old specimens that we used. In addition, the amino acid racemization test strongly suggests that reasonably well preserved DNA should be present in those specimens. Because DNA from all four Cro-Magnon type bone fragments could be amplified and sequenced only by using primers specific for modern humans, and not for Neandertals, there is little doubt that the mtDNAs of early a.m.h. and of cronologically close Neandertals were, at least, very different.[/i] Indeed, DNA do contaminate or deteriorate over a certain amount of time, as has been pointed out here time and again, and provide false impression of sequences. The author alerts potential readers of such, or at least make the reader take such matter into consideration. More over, from that same link: [i] [b]Paglicci-12 shows the motifs 00073G, 10873C, 10238T, and AACC between nucleotide positions 10397 and 10400, which allows the classification of this sequence into the macrohaplogroupN, containing haplogroups W, X, I, N1a, N1b, N1c, and N*. [/b][/i] The presence of such nucleotide motifs [we are not told here, is whether these are just detections of known motifs found in N haplogroups which are known to occupy specific designated positions across the entire N macrohaplogroup/ N sub-haplogroups…or whether they actually both resemble known motifs and actually occupy the same positions as those known motifs] in between the said motif [i]‘positions’[/i] [as designated in the Cambridge reference sequence], is what the author(s) are basing their conclusions off; what they don’t say and perhaps cannot say, is into which [b]specific[/b] N mtDNA sub-haplogroup, do the said ancient mtDNA fall. For this to be determined, similarities of sequences at [b]specific[/b] loci between designated mtDNA haplotypes within the N sub-haplogroup have to be shown. The author doesn’t do this; rather gives the impression of “suspicion” that the said ancient DNA belong to the N haplogroup, for the reason just stated. More from the study: [i]Following the definition given in ref. 36, the presence of a [b]single mutation in 16,223 within HRVI[/b] suggests a classification of Paglicci-12 into the haplogroup N*, which is observed today in several samples from the Near East and, at lower frequencies, in the Caucasus (35).[/i] Thus here, the author(s) is basing the generalization of the ancient specimen mtDNA into the N paragroup, via extrapolation from a single mutation in the nucleotide position designated by the nucleotide sequence ‘16233’ by the Cambridge reference sequence. The author(s) makes the said extrapolation from this referenced study, as the author(s) make note of: “As before, we denote sequence types in terms of the positions at which they differ from the CRS, [b]so that an HVS-I sequence type differing by a transition at nucleotide position 16311 is denoted “16311,” and a type differing by transitions at nucleotide positions 16145 and 16223 and a C→G transversion at nucleotide position 16176 is denoted “16145-16176G-16223.”[/b] The term “founder type” denotes a sequence type that has been carried from a source population to a derived population. “Founder cluster” refers to the cluster that has evolved from the founder type in the derived population.” - Richards. et al. And then the author(s) note: [i]It is [b]difficult to say[/b] whether the apparent evolutionary relationship between Paglicci-25 and Paglicci-12 and those populations is [b]more than a coincidence.[/b] Indeed, the haplogroups to which the Cro-Magnon type [b]sequences appear to belong are RARE among modern samples[/b], and therefore their frequencies are poorly estimated.[/i] Thus, if some one is to put any faith in these ancient mtDNA data, and ‘cautiously’ at that, the least that can be said is that, this simply says that those mtDNA of the so-called “Cro-Magnon” type remains analyzed here, were not much different from those in modern/contemporary groups, and perhaps, exemplifies a common source of the lineages, which would be L3. Otherwise, I suspect the author(s) would have at least informed us about which [b]specific[/b] N sub-haplogroups, the ancient mtDNA samples fall into. Instead again, we are told: [i]“Indeed, the haplogroups to which the Cro-Magnon type sequences appear to belong are rare among modern samples, and therefore their frequencies are poorly estimated.”[/i] We need to delineate what the author(s) is referring to, which is: What is dubbed [b]"Paglicci-25"[/b] sample, and what is dubbed [b]"Paglicci-12"[/b] sample. The former, i.e. Paglicci-25 sample, is claimed to have motifis which suggest affiliation with the either [i]Pre-HV[/i] or [i]HV[/i] haplogroup (which split to give rise to haplogroups H and V), which are all part of the N macro-haplogroup. This is perhaps an indication of the kind of ambiguity the authors are dealing with. They see relationships between the ancient mtDNA extracts and the N macro-haplogroup. [i][b]Paglicci-25[/b] has the following motifs: +7,025 AluI, 00073A, 11719G, and 12308A. Therefore, this sequence belongs to either haplogroups HV or pre-HV, two haplogroups rare in general but with a comparatively high frequencies among today's Near-Easterners (35).[/i] The latter, i.e. Paglicci-12 sample, show affiliation with any of the mentioned N sub-haplogroups, which were: [i][b]Paglicci-12[/b] shows the motifs 00073G, 10873C, 10238T, and AACC between nucleotide positions 10397 and 10400, which allows the classification of this sequence into the macrohaplogroup N, containing haplogroups W, X, I, N1a, N1b, N1c, and N*.[/i] Discussed [URL=http://www.egyptsearch.com/forums/ultimatebb.cgi?ubb=get_topic;f=8;t=003653]here[/URL] That said, if the said lineages are [i]definitely[/i] long drifted-out rare Hg N markers, and if they indeed belong to what is dubbed as "Cro-Magnon", then it may well serve the purpose of placing the Cro-Magnon type as likely ancestors of contemporary European groups [as noted in the intro]. The presence of Hg N markers in the so-called "Near East" would lend support to the use of the "Near Eastern" corridor in the peopling of the European subcontinent. A case can be made however, such prospect can open up the possibility that the Cro-Magnon types miscegenated with groups in the migration route through such a corridor. Clearly there are some maternal DNA evolutionary gaps between the Paglicci-25 specimen and that of Paglicci-12 specimen [the latter involving the relatively older evolutionary time frame], if one is to go by Caramelli et al.'s findings. Yet, they are supposed to belong to the same general era (Gravettian). [/QB][/QUOTE]
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