Genes (Basel) . 2022 Mar 17;13(3):533. doi: 10.3390/genes13030533.
Circum-Saharan Prehistory through the Lens of mtDNA Diversity Mame Yoro Diallo 1 2, Martina Číková 1, Iva Kulichová 2 3, Elika Podgorná 1, Edita Priehodová 1, Jana Nováčková 3, Veronica Fernandes 4 5, Luísa Pereira 4 5, Viktor Černý 1 Affiliations expand PMID: 35328086 PMCID: PMC8951852 DOI: 10.3390/genes13030533
Abstract African history has been significantly influenced by the Sahara, which has represented a barrier for migrations of all living beings, including humans. Major exceptions were the gene flow events that took place between North African and sub-Saharan populations during the so-called African Humid Periods, especially in the Early Holocene (11.5 to 5.5 thousand years ago), and more recently in connection with trans-Saharan commercial routes. In this study, we describe mitochondrial DNA (mtDNA) diversity of human populations from both sides of the Sahara Desert, i.e., both from North Africa and the Sahel/Savannah belt. The final dataset of 7213 mtDNA sequences from 134 African populations encompasses 470 newly collected and 6743 previously published samples, which were analyzed using descriptive methods and Bayesian statistics. We completely sequenced 26 mtDNAs from sub-Saharan samples belonging to the Eurasian haplogroup N1. Analyses of these N1 mitogenomes revealed their possible routes to the Sahel, mostly via Bab el-Mandab. Our results indicate that maternal gene flow must have been important in this circum-Saharan space, not only within North Africa and the Sahel/Savannah belt but also between these two regions.
a large proportion of N1 lineages from the Sahel/Savannah belt and from eastern Africa (Somalia, Sudan, Ethiopia, Kenya, and Tanzania), which are affiliated in N1a1a and N1b2 sub-branches, have the closest relatives in the Arabian Peninsula and are the oldest lineages in those sub-branches, while most I-Sahel/Savanah belt lineages are basal in the branches together with other European and Near Eastern sequences. When we look at the age of the N1a1a and N1b2 clusters (Table 2 and Supplementary Table S9), we can see age estimates at most around 20 ka, whereby these should be interpreted as the upper limit age of introgression of these lineages into the Sahel.
It seems that periodically, both in a long-term and short-term view, an increase in the size of the shallow Lake Chad in the middle of the east-western Sahelian corridor presented an obstacle to gene flow, forming a cul-de-sac. This can be documented by the spread of two different populations of nomadic pastoralists: in the west the Fulani, such as Woɗaaɓe, and in the east the Arabs, such as Baggara or Shuwa. While the Arabs are of Eurasian (Arabian) ancestry and received gene flow from sub-Saharan Africans [28], the Fulani are of western African ancestry and their ancestors acquired some Eurasian ancestry by admixture with a northern African population possibly related to the Berbers [24,27]. Since the level of this admixture is relatively high (analyses show around 20% of a Eurasian component), it might be responsible for the noticeable differences between local Fulani populations and the surrounding relatively homogeneous Sahel/Savannah gene pool. On the other hand, the genetic diversity of sedentary farmers suggests that they lived in reproductively more isolated groups, which led to genetic drift and isolation by distance [10]. Interestingly, this can be associated also with the genetic diversity of their pearl millet landraces grown by different ethnolinguistic groups, especially in the western part of the Lake Chad Basin [83].
Finally, we found that the N1 haplogroup, which diversified in southwestern Asia some 55 ka [4] and its younger lineages expanded across all Eurasia, is present also in eastern Africa and the Sahel/Savannah belt. On the other hand, the age estimates of N1 mitogenomes we detected in our Sahelian populations are much younger and thus congruent with population contacts via Ba el-Mandeb or the Red Sea [84], not via the southern Mediterranean space. Moreover, two ancient samples from Takarkori rock shelter in Libya dated to ~7 ka [33] are highly distinct from our N1 Sahelian and eastern African samples because they branched off before all the current N lineages (far away from N1). We did not find any traces of local expansion of mtDNA N1a lineages into the Sahel/Savannah belt, as described for example for the Y chromosome R1b-V88 haplogroup [85,86] or for L3f3 mtDNA haplogroup [15]. This kind of (maternal) Eurasian N1 impact is visible mainly in eastern Africa, especially in Sudan, Somalia, Ethiopia, Kenya, and Tanzania, and not further in the central or even western part of the Sahel/Savannah belt close to the Lake Chad Basin. In fact, migration associated with this N1 African diversity might be associated with the Late Pleistocene/Holocene expansions in Arabia and the neighboring region and more recently also with the spread of Ethiosemitic languages into Ethiopia at ~3 ka (for example N1a3a+195C!), which continued further to South Africa [87] and not to the west.
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Haplogroup I is a fairly rare matrilinear lineage, being found in average in 2% of Europeans and under 1% of Near Easterners....
Haplogroup N1a, excluding the N1a1b2 subclade (i.e. haplogroup I), is even rarer, being found is less than 0.5% of the European population. N1a(xI) is most common in Yemen (2.5%), Saudi Arabia (2.5%), Kazakhstan (1.5%), Egypt (1%), Armenia (1%), Bosnia-Herzegovina (1%), Lithuania (1%) and Estonia (1%). There seems to be an overlap in distribution between haplogroups N1a and I in the Dinaric Alps and Baltic countries.
The earliest evidence of N1a in Europe comes from the Early Neolithic, when it suddenly pops up in 16 of the 146 skeletons tested to date from various sites of the Starčevo culture (7% of all samples) in Croatia and Hungary, and especially the Linear Pottery culture (LBK) in Germany (see Adler 2012 and Brandt 2013), where it reaches the spectacularly high frequency of 12.75%. This may have been due to a founder effect among LBK farmers, but it is noteworthy that later Neolithic cultures in the region kept high levels of N1a compared to modern Germany. That included samples from the Rössen (9%) and Schöningen (3%) cultures, as well as the Baalberge (5%) and Salzmünde (7%) groups of the Funnelbeaker culture, spanning the whole Neolithic and early Chalcolithic periods. These German samples belonged to the N1a1a, N1a1a1 and N1a1a3 subclades.
From the time of the Corded Ware culture, representing the advance of Proto-Indo-European speakers from the Pontic Steppe of Ukraine and southern Russia, haplogroup N1a suddenly disappears from the record in Central Europe, and would never come back.
N1a was also found in the Alföld culture in Hungary, an eastern branch of the Linear Pottery culture, as well as in Megalithic France.
Nowadays N1a is also found in modern Cushitic populations of East Africa. In fact, the same N1a1a3 that was found in Neolithic Germany is now found essentially in Somalia and Ethiopia, in the Horn of Africa. This region has the world's highest frequency of Y-haplogroup T, the greatest diversity of Y-haplogroup E1b1b, and also a substantial percentage of Y-haplogroup J1, three paternal lineages thought to have been found among early agriculturalists from the Fertile Crescent alongside Y-haplogroup G2 - four of the "Neolithic founder Y-DNA haplogroups". Therefore it is possible that N1a originated with Y-haplogroup G2, J1 and/or T during the Upper Paleolithic, then spread with all four haplogroups after G2a converged with E1b1b and T in the Fertile Crescent later during the Neolithic period.
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I forgot, oh well. That earlier thread only got one reply. I should have checked But in this version I have a bigger quote and then in my second post additional N1 info, I had since noticed one of the Natufians was N1 and 3 of the later period Abusir El-Meleq mummies are
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I have heard a Yoruban say his maternal line is N1 I will bet there is more N closer to the coast than that map says, those delineations are highly convenient considering there where no borders less than 150 years ago.
And, on top of that Old Oyo being prolific slave traders, pretty sure they kept many female slaves from the inner sahel in their harems.
-------------------- It's not my burden to disabuse the ignorant of their wrong opinions Posts: 2699 | From: New York | Registered: Jun 2015
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quote:Originally posted by Yatunde Lisa Bey: I have heard a Yoruban say his maternal line is N1 I will bet there is more N closer to the coast than that map says, those delineations are highly convenient considering there where no borders less than 150 years ago.
And, on top of that Old Oyo being prolific slave traders, pretty sure they kept many female slaves from the inner sahel in their harems.
Geneflow isn't spread linearly though. To know whether the distribution makes sense you'd have to take into consideration the natural barrier such as mountains, canyons, climate, distance and even culture, may all play a role in how it eventually distributed. For example, if there are 3 groups of people where 2 groups speak a mutually intelligible language (whether that be a traditional or trade language), and one of those 2 groups carry a novel ancestry in the region, the geneflow will be biased towards the group that speaks a similar language, than the group that doesn't because we interact more with people who understand us.
That begs the questions: Where was the entry point for the ancestry, what did the corridor between that entry point and the area (ou believe the ancestry would be more widespread in) look like, and what was the overlap in the material cultures?
Posts: 44 | From: West Bumble... | Registered: Apr 2017
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quote:Originally posted by Yatunde Lisa Bey: I have heard a Yoruban say his maternal line is N1 I will bet there is more N closer to the coast than that map says, those delineations are highly convenient considering there where no borders less than 150 years ago.
And, on top of that Old Oyo being prolific slave traders, pretty sure they kept many female slaves from the inner sahel in their harems.
Geneflow isn't spread linearly though. To know whether the distribution makes sense you'd have to take into consideration the natural barrier such as mountains, canyons, climate, distance and even culture, may all play a role in how it eventually distributed. For example, if there are 3 groups of people where 2 groups speak a mutually intelligible language (whether that be a traditional or trade language), and one of those 2 groups carry a novel ancestry in the region, the geneflow will be biased towards the group that speaks a similar language, than the group that doesn't because we interact more with people who understand us.
That begs the questions: Where was the entry point for the ancestry, what did the corridor between that entry point and the area (ou believe the ancestry would be more widespread in) look like, and what was the overlap in the material cultures?
Do you know the geography between Kano and Khartoum?
-------------------- It's not my burden to disabuse the ignorant of their wrong opinions Posts: 2699 | From: New York | Registered: Jun 2015
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quote:Originally posted by Yatunde Lisa Bey: I have heard a Yoruban say his maternal line is N1 I will bet there is more N closer to the coast than that map says, those delineations are highly convenient considering there where no borders less than 150 years ago.
And, on top of that Old Oyo being prolific slave traders, pretty sure they kept many female slaves from the inner sahel in their harems.
Geneflow isn't spread linearly though. To know whether the distribution makes sense you'd have to take into consideration the natural barrier such as mountains, canyons, climate, distance and even culture, may all play a role in how it eventually distributed. For example, if there are 3 groups of people where 2 groups speak a mutually intelligible language (whether that be a traditional or trade language), and one of those 2 groups carry a novel ancestry in the region, the geneflow will be biased towards the group that speaks a similar language, than the group that doesn't because we interact more with people who understand us.
That begs the questions: Where was the entry point for the ancestry, what did the corridor between that entry point and the area (ou believe the ancestry would be more widespread in) look like, and what was the overlap in the material cultures?
Do you know the geography between Kano and Khartoum?
Khartoum was the entry point for this lineage? At what date was it found in Khartoum and what material culture is it associated with there?
Posts: 44 | From: West Bumble... | Registered: Apr 2017
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