quote:The Youngest Toba eruption has been linked to a genetic bottleneck in human evolution about 70,000 years ago,[31][32] which may have resulted in a severe reduction in the size of the total human population due to the effects of the eruption on the global climate.[33] According to the genetic bottleneck theory, between 50,000 and 100,000 years ago, human populations sharply decreased to 3,000–10,000 surviving individuals.[34][35] It is supported by some genetic evidence suggesting that today's humans are descended from a very small population of between 1,000 and 10,000 breeding pairs that existed about 70,000 years ago.[36][37]
But wait
quote:A 2018 study by Chad Yost and colleagues of cores from Lake Malawi dating to the period of the Youngest Toba eruption showed no evidence of a volcanic winter, and they argue that there was no effect on African humans.
Its oldest branch are N1 and R. There is a lot of African diversity off of R because R births R0, U and HV.
U6 is big sister.
and H.
This might be conceivable if the African diversity was off of a late divergent V or Y branch. lineages grow too incrementally. They are larger when they are younger and newer with more parents. Africa's diversity is mostly near the base of N because R is its oldest branch and it leads to early R0 HV, H1, U6, U8,K etc.
posted
This is the most famous article talking about back migration into Africa. the time periods talked about are 12,000 and 1,200 years ago. These are typical time periods discussed in subsequent articles. So this other 50,000 being talked about is much older than the periods talked about called "back migration" to Africa
Genomic Ancestry of North Africans Supports Back-to-Africa Migrations Brenna M. Henn 2012
Abstract North African populations are distinct from sub-Saharan Africans based on cultural, linguistic, and phenotypic attributes; however, the time and the extent of genetic divergence between populations north and south of the Sahara remain poorly understood. Here, we interrogate the multilayered history of North Africa by characterizing the effect of hypothesized migrations from the Near East, Europe, and sub-Saharan Africa on current genetic diversity. We present dense, genome-wide SNP genotyping array data (730,000 sites) from seven North African populations, spanning from Egypt to Morocco, and one Spanish population. We identify a gradient of likely autochthonous Maghrebi ancestry that increases from east to west across northern Africa; this ancestry is likely derived from “back-to-Africa” gene flow more than 12,000 years ago (ya),prior to the Holocene. The indigenous North African ancestry is more frequent in populations with historical Berber ethnicity. In most North African populations we also see substantial shared ancestry with the Near East, and to a lesser extent sub-Saharan Africa and Europe. To estimate the time of migration from sub-Saharan populations into North Africa, we implement a maximum likelihood dating method based on the distribution of migrant tracts. In order to first identify migrant tracts, we assign local ancestry to haplotypes using a novel, principal component-based analysis of three ancestral populations.We estimate that a migration of western African origin into Morocco began about 40 generations ago (approximately 1,200 ya); a migration of individuals with Nilotic ancestry into Egypt occurred about 25 generations ago (approximately 750 ya). Our genomic data reveal an extraordinarily complex history of migrations, involving at least five ancestral populations, into North Africa. _____
Posts: 42935 | From: , | Registered: Jan 2010
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Doesn't Taforalt contradict that abstract? Older than 12k with autochthonous Maghrebi ancestry that increases from east to west across northern Africa. If you are making a case for a return to Africa, shouldn't it decrease? If this happened 12k years ago why does Taforalt have U6 and why is U rendered like this?
Afalou was older than 12k with R0, JT, H1, Xb and T2. There is a logical issue. The branches that are more common in Africa tend to be old or off old branches. With recent samples we know they are already there. You need this be old but this old population doesn't exist.
Posts: 1254 | From: howdy | Registered: Mar 2014
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quote:Originally posted by Forty2Tribes: Doesn't Taforalt contradict that abstract? Older than 12k with autochthonous Maghrebi ancestry that increases from east to west across northern Africa. If you are making a case for a return to Africa, shouldn't it decrease? If this happened 12k years ago why does Taforalt have U6 and why is U rendered like this?
Afalou was older than 12k with R0, JT, H1, Xb and T2. There is a logical issue. The branches that are more common in Africa tend to be old or off old branches. With recent samples we know they are already there. You need this be old but this old population doesn't exist.
You would be talking about what researchers would say represents an earlier additional back migration to 15k or earlier on the maternal side. In Africa U6 is mainly in the Maghreb and is less influential on other regions of Africa as was the theoretical back migrations Brenna Henn was talking about
On the chart at the root of U6 is "Peștera Muierii" that is considered the basal original U6 before it split into the later various a,b,c and d mutations. That is a location in Romania, female remains found in a cave there, it's on the map The highest diversity is in Iberia. The highest frequencies are in the Maghreb and are usually U6b
So what happens in theory is that carries of U6 are in one region and there are other people there of different haplogroups also 'competing"
Then some people who carry the group go migrate somewhere else into a less populated region and settle there. Then their haplogroup could become the dominant one with the largest numbers in that region
So the high frequency could be a hint that a place could be the origin but it might not be. Higher diversity can be more suggestive of origin due to more different clades of the same group being in that location. For instance Hap H is very high in Tuareg but low diversity and at the same time is the most common mtDNA in Europe where it has higher diversity. Then, if a discovery of remains is found and it is older than anything else that becomes another suggestion of origin. So they put all this together and try to estimate the origin
Posts: 42935 | From: , | Registered: Jan 2010
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Its oldest branch are N1 and R. There is a lot of African diversity off of R because R births R0, U and HV.
This is the flaw in your analysis. As previously discussed, The oldest Sublcades of M and N are NOT those of West Asia like R and N1.
quote: In early mtDNA phylogeographic studies, the virtual absence of mtDNA haplogroup M in the Levant, and its presence in Ethiopia, southern Arabia, the Indian subcontinent and East Asia, rendered M the first genetic indicator of a southern-route exit from eastern Africa [19]. Shortly after these studies, based on the rarity of mtDNA haplogroup N(xR) in India, and its continuous presence above the Himalayas, we proposed an additional northern route through the Levant [4]. Since that time, intensive and extensive research on mtDNA has been carried out, on populations not only from Central [20,21,22,23] and East Asia [24,25,26] but also from the regions along the hypothetical southern route, such as India [27,28,29,30], mainland southeastern Asia [31,32,33], island southeast Asia [34,35,36,37,38,39], New Guinea, North Island, Melanesia and Australia [40,41,42,43,44]. The most unexpected results were that some N haplogroups in southern China (N10, N11) were older than the oldest N western Asia lineages (N1, N2), and that some M haplogroups in Melanesia (M27, Q) were older than the oldest Indian M lineages (M2, M33). Different researchers have provided conflicting interpretations of these results. Some perceived them as confirming a rapid, southern coastal spread of modern humans from Africa [30, 45,46,47]. Others postulate ancient local population differentiation in each region without any evidence of the shared ancestry expected by the southern dispersal model [48,49,50]. The existence of a northern route, deduced from the phylogeography of macrohaplogroup N [4], has received additional support from the fossil record [11], whole-genome studies comparing Egyptian and Ethiopian populations [51], and the fact that all non-African populations present a signal of Neanderthal introgression [52]. However, we realized that what actually macrohaplogroup N suggests is a human movement from southeastern Asia to western Asia [53]. We observed the same tendency for macrohaplogroup M, in this case, expanding westwards to India [54]. A similar trend was observed for macrohaplogroup R, the main sister branch of N [55]. Thus, we confirmed that macrohaplogroup M and N indicated, major southern and northern expansions, respectively, of modern humans but, in the opposite sense we had predicted previously [4]. Studies based on Y-chromosome sequences also suggested southeastern Asia as an early center of human expansions
The DATA is correct on the spread of M and N, although i dont buy the backmigration of L3 based on the presence of Dead End Fossils in Asia and non-existence of Asian specific L3(xL3M,L3N) Also the East to West Migration of the oldest Eurasian paternal linages argued 2 years after this publication with a different finding from a totally different team of individuals. It states below:
quote: Here, we show that phylogenetic analyses of haplogroup C, D and FT sequences, including very rare deep-rooting lineages, together with phylogeographic analyses of ancient and present-day non-African Y chromosomes, all point to East/Southeast Asia as the origin 50,000-55,000 years ago of all known surviving non-African male lineages (apart from recent migrants). This observation contrasts with the expectation of a West Eurasian origin predicted by a simple model of expansion from a source near Africa, and can be interpreted as resulting from extensive genetic drift in the initial population or replacement of early western Y lineages from the east, thus informing and constraining models of the initial expansion.
I think you are making the mistake of Viewing West Asian and North Africa M and N in a bubble and not being acquainted with the diversity and AGE of these M and N lineages in Southern Asia, South East Asia, and Oceania. It gives a false impression of what's going on. I see others do the same thing looking at North Africa genetics in a bubble without using Equatorial African data as a reference point to see how the North came to be in the first place.
Thank you for coming to my Ted Talk.
Posts: 2463 | From: New Jersey USA | Registered: Dec 2007
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I'm going by phylogenetic trees. Do you know of one that has N10,N11? Does anything show that either is older than R? N1 is still old in comparison to the European and West Asian branches and R's estimated age overlaps N's estimated age so Id assume that its N's oldest branch and obviously its the largest.
This is a pattern of fore migration. M,M1,N,R,U, would be born somewhere near Kenya and the Sudan move up when the Sahara is good, out of Africa so the older branches have less competition or no competition the further they travel. Then they travel deeper into Africa in large enough waves to beat out L while creating the oldest and fattest branch off of N which has to be N-R-U-H then leave an early fat branch of H and U in Northwestish Africa before traveling to Europe and blowing up initially because Europe was pretty empty and later with farming.
I can see that scenario. What I can't see is how the least genetically diverse people who we already know descend from Africans would come back and parent that much of Africa in that pattern especially if Africa wasn't effected by the Toba eruption.
Also I am looking at greater Africa. We don't see this in admixture charts. Based on Admixture and SNP analysis we have North African ancestry in east Africans. We don't have it in east Asians.
Posts: 1254 | From: howdy | Registered: Mar 2014
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quote:Originally posted by beyoku: Brother, did you read the articles i posted? Have you read ANY other studies on M and N OUTSIDE of The Middle East and Africa?
The OLDEST M and N are found East of India.
This is very true.
Posts: 1891 | From: NY | Registered: Sep 2014
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quote:Originally posted by beyoku: Brother, did you read the articles i posted? Have you read ANY other studies on M and N OUTSIDE of The Middle East and Africa?
The OLDEST M and N are found East of India.
Did you read my response? I said that R which is a branch off of N is really old. I don't know if its older than N10 because you didn't provide a source on it's age but I suspect that it is because its age overlaps N in most predictions and I never see N10 on phylogenetic trees. I do see M1. So what lineages of M are older than M1?
Posts: 1254 | From: howdy | Registered: Mar 2014
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