...
Post A Reply
my profile
|
directory
login
|
register
|
search
|
faq
|
forum home
»
EgyptSearch Forums
»
Egyptology
»
Pleistocene North African genomes link Near Eastern and sub-Saharan African human pop
» Post A Reply
Post A Reply
Login Name:
Password:
Message Icon:
Message:
HTML is not enabled.
UBB Code™ is enabled.
[QUOTE]Originally posted by Tukuler: [QB] Good arguments all around. A method implied by Swenet will tell us a lot; line up as much of the mitogenomes accessible to ascertain any lineal direct relationships of Roumania & Maghreb. Meanwhile are the authors misleadingly pointing to PM1 U6 ancestral to U6a'b'd'c? [IMG]https://images2.imgbox.com/8f/42/2S1uVO2J_o.jpg[/IMG][b] Figure 2. Distribution of the U6 mitochondrial lineages. (A) [/b]Phylogenetic analysis and temporal estimates for lineages including the Pestera Muierii-1 (PM1) from the mitochondrial tree. In lieu of editing my last post here's some relevant Hirbo for some reason last August I took notes on . Sorry for block of text. If I underscored points it'd only take away from the overall presentation. " Middle Paleolithic tool industries of northeast Africa, which might have served as transition technology to the Near East, have been broadly classified into two complexes: Nubian that is riverine that probably expanded northward from the Sudan, and the Lower Nile valley complex [586]. The Lower Nile valley complex is described as flexible, which made it possible for its users to adapt and exploit different environments including the desert [586]. The Lower Nile valley complex is considered as a continuation of industry practiced by earlier occupiers of the Nile Valley (from 90 kya), before subsequent transition to Upper Paleolithic industry around 40 kya [586]. Similarity between stone tool technologies dated to between 35-44 kya at Nazlet khater 4 in Egypt and those used at the site in the Levant (Boker Tachtit) [691, 692] serves as evidence of a transition of modern humans from Africa to Eurasia. In fact, archeological findings from several 30 - 50 kyo sites in the Levant have been termed “transitional industries” between the Middle and Upper Paleolithic [29]. The Upper Paleolithic industries thought to be the work of modern humans seem to have appeared somewhat earlier in western Asia than in Europe [29]. Some historians argue that the 40 kya common tradition that marks the behavioral modernity sometimes attributed to Neanderthal (art, personal decoration, ritualized burials, formal bone tools and gift exchange), might represent the expansion of Upper Paleolithic anatomically modern human populations across Europe [393, 685, 693]. Despite the fact that Europe was settled by modern humans by the end of the Middle Paleolithic (by 30 kya) [404, 694], the early European modern human fossil evidence from Mladec (28 kya) [695] exhibit features that support substantial and relatively recent African ancestry [26]. Moreover, a study of comparison in body proportions of skeleton samples from the European Early Upper Paleolithic (30 -20 kya) shows that they cluster with recent African samples rather than European Late upper Paleolithic (19-10 kya) samples indicating that there was some gene flow and/or migration from Africa associated with the emergence of modern humans in Europe [696]. Therefore, the sequence of historical events and archaeological evidence above, indicates that the expansion from Africa into Southwest Asia might have taken place around 40 - 50 kya. This is further supported by anatomically modern human produced tools shared between North Africa and the Near east [697]. During two periods, the African faunal zone seems to have extended briefly into the Near East and allowed modern humans to expand their range out of Africa into southwestern Asia [698] before contracting back [699]. These two periods, about 100 kya and 50 kya, coincide with the initial unsuccessful and the second the later expansion out of Africa, respectively [29, 148, 684, 686]. Therefore, the contiguous area that constitutes part of north Africa, specifically the Nile valley and near East, might have also acted as a corridor of human range expansion from Africa and population contraction back to Africa from 40 kya up to the late Pleistocene (20 kya) [586]. The scenario described above fits the genetic evidence and time period for modern human dispersal from Africa through the northern route [17], mostly by individuals with R0 mtDNA lineages (sub-family of the N-clade). Based on principal components analysis (PCA) of a dataset of 940 individuals from 53 representative global populations typed at ~650,000 SNPs as part of the Human Genome Diversity Project [343], Reich et al., [555] speculated that there was sub-Saharan African gene flow into Europe and the rest of Eurasia. Moreover, based on a novel PCA and clustering method which was used to determine the phylogeny of 1737 complete human mtDNA sequences, Alexe et al., [191] argued that M and N mtDNA clades arose due to two different migration events that represent the previously described southern and northern routes respectively. They [191] further argue that the N carrying population that followed the northern route split along an East-West geographic division, resulting in a western “European R clade” containing the haplogroups H, V, H/V, J, T and U, and an eastern “Eurasian N subclade” containing haplogroups B, R5, F, A, N9, I, W and X. However, considering the distribution pattern of the „Eurasian N-clades‟ in Southeast Asia, the 408 Pacific and the Americas, some of the N clades might have been present in individuals who followed the southern route. Interestingly, the R clades that are found in South/Southeast Asia and the Americas (A, B, F, N9, R5-R11, P and Y) seem to have split off from other R clades that are mainly found in the Near East and Europe about 50-70 kya [190]. Such a scenario may indicate that the N clade split within Africa before its expansion out of Africa. The M haplogroup, whose M1 haplotype is predominantly East African and whose other haplotypes are found in the Indian subcontinent and southeastern Asia, might also reflect a population split just before/or after the out-of Africa migration, with most of the M haplotype carrying populations expanding through the southern route. The TMRCA age estimates based on ~4600 sequences – N=3191, M=1416 (60 from this study and the rest from previously published data) of the N and M haplogroup lineages are 41 – 67 ky (Kivisild et al., [220] 62.11±6.09 ky and Mishmar et al., [178] 47.92±6.98 ky) and 41 – 62 (Kivisild et al., [220] 55.76±4.36 ky and Mishmar et al., [178] 45.11±4.53 ky), respectively (Appendix 7b). These age estimates for the two haplogroups concurs with estimates done using a corrected time-dependent mutation rate based on the entire mtDNA genome using a maximum likelihood method which estimated the TMRCA of the N haplogroup to be 76.92±17.53 ky and the TMRCA of the M haplogroup to be 73.3±9.64 ky [190] (Appendix 7b). It is still not yet clear whether M and N arose in Africa just before the exodus, or just after it (as indicated by the close relationship and similar ages for M and N (as estimated above), but it is highly unlikely that it happened further east in India as speculated elsewhere [598] based on high diversity of M [412, 600, 700, 701]. The ages of the haplogroups coupled with the distribution pattern of N and M haplotypes described above are consistent with the 409 hypothesis that they diverged prior to migration of modern humans out of Africa or just after it. This time period coincides perfectly with the return to warm, moist conditions in global climate after volcanic ash from the Mt. Toba eruption (which took place 73 kya in modern-day Sumatra) dissipated. The effects of the eruption on the tropics and sub tropics were reduced temperature, precipitation and increased aridity, and may have lasted until 60 kya [393]. It is hypothesized that these events led to a contraction of the human population, reducing genetic diversity and limiting the distribution of human populations to areas with climatically favorable conditions and ecologically stable environments [48, 110, 393]. The climatic conditions improved around 57 kya with increased insolation (solar radiation received) and precipitation in northern Africa [393]. During dry periods, environmental barriers associated with the severity of the Sahara desert could have made the northern route difficult, so it is likely that this route was more suitable during wetter climatic periods [702]; thus the expansion may have been more likely during the wet periods of 43-57 kya [393, 592]. Recent study‟s [703] findings of a crude age estimate (13.6 – 108.4 kya) and distribution pattern of 17q21 inversion (microtubular associated protein tau (MAPT) inversion), mainly across Europe, Central and southwestern Asia and Africa [703], also seem to conform to northern route out-of-Africa human and Neolithic expansion. " [/QB][/QUOTE]
Instant Graemlins
Instant UBB Code™
What is UBB Code™?
Options
Disable Graemlins in this post.
*** Click here to review this topic. ***
Contact Us
|
EgyptSearch!
(c) 2015 EgyptSearch.com
Powered by UBB.classic™ 6.7.3