Post by djoser-xyyman on Aug 14, 2014 8:01:29 GMT -5
Admixture??
These geneticist know there is no admixture or back-migration. They had known this for a long time. If “I” know this , they know it also.Rosenberge et al 2002
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Fig. 1 and table S2). In several populations, individuals had partial membership in multiple clusters, with similar membership coefficients for most individuals. These populations might reflect CONTINUOUS GRADATIONS IN ALLELE FREQUENCIES ACROSS REGIONS *****or *****admixture of neighboring groups.
Inferred clusters for Africa and the Middle East were also consistent across runs but did not all correspond to predefined groups. For the other samples, among-population variance components were below 2%, and independent structure runs were less consistent. For K _
Europe, with the smallest among-population variance component (0.7%), was THE MOST DIFFICULT REGION IN WHICH TO DETECT POPULATION STRUCTURE. The highest-likelihood run for K _ 3 found no structure; in other runs, Basque and Sardinian were identified as distinctive. Russians variously grouped with Adygei and Orcadians; Russian-Orcadian similarity might derive from shared Viking contributions (17). French, Italians, and Tuscans showed mixed membership in clusters that contained other populations. Because genetic drift occurs rapidly
Genetic Structure of Human Populations =
Noah A. Rosenberg,1 2002
Europe, with the smallest among-population
variance component (0.7%), was the most difficult region in which to detect population structure.
The highest-likelihood run for K 3 found no structure; in other runs, Basque and Sardinian were identified as distinctive.
Support from the relationship of genetic and geographic distance in human populations for a serial founder effect originating in Africa
www.pnas.org/content/102/44/15942.long
Pickrell et al. "Ancient west Eurasian ancestry in southern and eastern Africa". PNAS, 2014.
www.pnas.org/content/early/2014/01/29/1313787111.abstract
These geneticist know there is no admixture or back-migration. They had known this for a long time. If “I” know this , they know it also.Rosenberge et al 2002
----------
Fig. 1 and table S2). In several populations, individuals had partial membership in multiple clusters, with similar membership coefficients for most individuals. These populations might reflect CONTINUOUS GRADATIONS IN ALLELE FREQUENCIES ACROSS REGIONS *****or *****admixture of neighboring groups.
Inferred clusters for Africa and the Middle East were also consistent across runs but did not all correspond to predefined groups. For the other samples, among-population variance components were below 2%, and independent structure runs were less consistent. For K _
Europe, with the smallest among-population variance component (0.7%), was THE MOST DIFFICULT REGION IN WHICH TO DETECT POPULATION STRUCTURE. The highest-likelihood run for K _ 3 found no structure; in other runs, Basque and Sardinian were identified as distinctive. Russians variously grouped with Adygei and Orcadians; Russian-Orcadian similarity might derive from shared Viking contributions (17). French, Italians, and Tuscans showed mixed membership in clusters that contained other populations. Because genetic drift occurs rapidly
Genetic Structure of Human Populations =
Noah A. Rosenberg,1 2002
Europe, with the smallest among-population
variance component (0.7%), was the most difficult region in which to detect population structure.
The highest-likelihood run for K 3 found no structure; in other runs, Basque and Sardinian were identified as distinctive.
Support from the relationship of genetic and geographic distance in human populations for a serial founder effect originating in Africa
www.pnas.org/content/102/44/15942.long
Jul 4, 2014 16:37:29 GMT -5 @ben said:
Most the admixture was probably in the last 3000 years. Their dates just need to be revised.Pickrell et al. "Ancient west Eurasian ancestry in southern and eastern Africa". PNAS, 2014.
www.pnas.org/content/early/2014/01/29/1313787111.abstract
One involved populations related to Niger–Congo-speaking African populations, and the other introduced ancestry most closely related to west Eurasian (European or Middle Eastern) populations. We date this latter admixture event to ∼900–1,800 y ago and show that it had the largest demographic impact in Khoisan populations that speak Khoe–Kwadi languages. A similar signal of west Eurasian ancestry is present throughout eastern Africa. In particular, we also find evidence for two admixture events in the history of Kenyan, Tanzanian, and Ethiopian populations, the earlier of which involved populations related to west Eurasians and which we date to ∼2,700–3,300 y ago.