PDA

View Full Version : which subclade(s) of R1b-V88 actualy went to Africa?



bicicleur
11-04-17, 10:11
acording to YFull TMRCA for R1b-V88 is 11.7 ka
but YFull shows only 1 African subclade, Y184858, formed 5.4 ka with TMRCA 1.95 ka
https://www.yfull.com/tree/R-Y7771/

are there more typical African herder subclades of R1b-V88 ?

Angela
11-04-17, 15:47
acording to YFull TMRCA for R1b-V88 is 11.7 ka
but YFull shows only 1 African subclade, Y184858, formed 5.4 ka with TMRCA 1.95 ka
https://www.yfull.com/tree/R-Y7771/

are there more typical African herder subclades of R1b-V88 ?

That's a good question. A TMRCA of 2,000 years ago seems awfully young.

Megalophias
11-04-17, 16:43
Actually even the other guy in Y18458 is a European, I think. So there is only one African on the tree at all.

V69 is found at quite high frequency in Central Africa and at lower frequency in Egypt. I'd say Y7771 as a whole is African. There also seems to be at least one case of FGC20973 in Chad.

bicicleur
11-04-17, 19:16
maybe it is because no or just a few African herders are tested by YFull
but is there any info available about to which subclades of R1b-V88 these African herders actualy belong?

bicicleur
11-04-17, 19:21
Actually even the other guy in Y18458 is a European, I think. So there is only one African on the tree at all.

V69 is found at quite high frequency in Central Africa and at lower frequency in Egypt. I'd say Y7771 as a whole is African. There also seems to be at least one case of FGC20973 in Chad.

then they all fall under subclade Y8447 with TRMCA 7 ka
this subclade isn't exclusive to Africa at all though

https://www.yfull.com/tree/R-Y8447/

there could have been some dispersal from some central place in different directions of which 1 group arrived in Africa

Angela
11-04-17, 20:16
You can take a look at Cruciani et al 2010, or maybe you already have:
http://www.nature.com/ejhg/journal/v18/n7/full/ejhg2009231a.html

Table 1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2987365/table/tbl1/

The above may not have enough detailed subclade resolution for you. Most of it seems to be just V69 or unresolved.

This is on Chad specifically, but it's autosomal. It's interesting though, especially in terms of dating.
http://www.cell.com/ajhg/abstract/S0002-9297(16)30448-7

"We have generated an extensive set of genotyping and high-coverage whole-genome sequencing data to study the genetic history of Chad and neighboring populations. We found substantial genetic differences between the ethnic groups inhabiting Chad today and suggest that multiple ancient Eurasian migrations played a major role in shaping the genetic diversity of the region (Figure 3 (http://www.cell.com/cms/attachment/2074117827/2068934805/gr3.jpg)C). Here, we discuss these migrations and how the mixed ancestry can confound proper interpretation of the evolutionary processes that occurred in their history and therefore needs to be thoroughly accounted for in the study of African genetic diversity.
We detected the earliest Eurasian migrations to Africa in the Laal-speaking people, an isolated language group of fewer than 800 speakers who inhabit southern Chad. We estimate that mixture occurred 4,750–7,200 ya, thus after the Neolithic transition in the Near East, a period characterized by exponential growth in human population size. Environmental changes during this period (which possibly triggered the Neolithic transition) also facilitated human migrations. The African Humid Period, for example, was a humid phase across North Africa that peaked 6,000–9,000 ya37 and biogeographically connected Africa to Eurasia, facilitating human movement across these regions.38 In Chad, we found a Y chromosome lineage (R1b-V88) that we estimate emerged during the same period 5,700–7,300 ya (Figure 3 (http://www.cell.com/cms/attachment/2074117827/2068934805/gr3.jpg)B). The closest related Y chromosome groups today are widespread in Eurasia and have been previously associated with human expansions to Europe.39, 40 We estimate that the Eurasian R1b lineages initially diverged 7,300–9,400 ya, at the time of the Neolithic expansions. However, we found that the African and Eurasian R1b lineages diverged 17,900–23,000 ya, suggesting that genetic structure was already established between the groups who expanded to Europe and Africa. R1b-V88 was previously found in Central and West Africa and was associated with a mid-Holocene migration of Afro-asiatic speakers through the central Sahara into the Lake Chad Basin.8 In the populations we examined, we found R1b in the Toubou and Sara, who speak Nilo-Saharan languages, and also in the Laal people, who speak an unclassified language. This suggests that R1b penetrated Africa independently of the Afro-asiatic language spread or passed to other groups through admixture.
In addition to the early Eurasian migration to Africa ∼6,000 ya, a second migration ∼3,000 ya affected the Toubou population in northern Chad but had no detectable genetic impact on other Chadian populations. This migration appears to be associated with the previously reported Eurasian backflow into East Africa, given that the source populations and dates of mixture are similar. Occurring at the start of the Iron Age, these migrations could have been facilitated by advances in warfare and transportation technology in the Near East. It is uncertain why the impact of this migration in Chad affected only the Toubou. The African ancestral component in the Toubou is best represented by the Laal-speaking population, suggesting that the African-Eurasian mixture probably occurred in Chad. However, ethnolinguistic barriers could have already been established at this time between the Chad groups, preventing a widespread dissemination of the Eurasian ancestry. The Toubou, despite their Islamic faith, do not show the genetic admixture detected in many Near Eastern and North African populations around 1,100 ya,41 suggesting conversion without population mixing at this time. They did, however, receive additional Eurasian ancestry in the past 200 years from a source represented by North African populations such as Tunisians, Mozabite, Algerians, and Sahrawi (Figure 3 (http://www.cell.com/cms/attachment/2074117827/2068934805/gr3.jpg)C). This recent interaction could have been promoted by the nomadic lifestyle of the present-day Toubou and a shared Muslim religion with North Africans. Unsurprisingly, we also detected a likely mixing of Chad populations in the sample from the capital, which could be even more recent.
Eurasian backflow into Africa thus appears to have been a recurrent event in the history of many Africans, given its considerable impact on their genomes. "

bicicleur
11-04-17, 21:36
the updated phylogeny in 2010 seems a bit outdated by now

V8 is not found in the YFull tree

in the 2010 paper there are 2 subclades of interest : V88* and V69
V69 includes the Y184858 where the YFull Nigeria is found
V88* in 2010 includes a lot of known subclades in 2017

the autosomal paper is a bit vague in their conclusions, but their estimate for the period when R1b-V88 emerged in Chadic seems more realistic
they also suggest the migration of R1b-V88 into Chadic was independant from the Afro-Asiatic (Natufian) migration

it seems to me YFull has to little Chadic R1b-V88 in their tree to give a correct view

it would be intersting to have the samples of 2010 retested and assigned to the subclades that are known today