Heterogeneity in Palaeolithic Population Continuity and Neolithic Expansion in N.Afr

[Angoliga]

(Serra-Vidal et. al, 2019 (https://doi.org/10.1016/j.cub.2019.09.050))

Highlights:

• Paleolithic genetic continuity is found in extant human North African genomes
• There is a West-to-East genetic cline of the Paleolithic component in North Africa
• Neolithization had a larger demographic impact than Arabization
• Differential admixture and genetic drift have modeled North African genomes


Summary:


North Africa is located at the crossroads of the Mediterranean Sea, the Middle East, and the Sahara Desert. Extensive migrations and gene flow in the region have shaped many different cultures and ancestral genetic components through time [1, 2, 3, 4, 5, 6]. DNA data from ancient Moroccan sites [7, 8] has recently shed some light to the population continuity-versus-replacement debate, i.e., the question of whether current North African populations descend from Palaeolithic groups or, on the contrary, subsequent migrations swept away all preexisting genetic signal in the region. In the present study, we analyze 21 complete North African genomes and compare them with extant and ancient genome data in order to address the demographic continuity-versus replacement debate, to assess whether these demographic events were homogeneous (including Berber and Arabic-speaking groups), and to explore the effect of Neolithization and posterior migration waves. The North African genetic pool is defined as a melting pot of genetic components, including an endemic North African Epipalaeolithic component at low frequency that forms a declining gradient from Western to Eastern North Africa. This scenario is consistent with Neolithization having shaped most of the current genetic variation in the region when compared to posterior back-to-North-Africa migration waves such as the Arabization. A common and distinct genetic history of the region is shown, with internal different proportions of genetic components owing to differential admixture with surrounding groups as well as to genetic drift due to isolation and endogamy in certain populations.
Fig. 1-4:

*Depending on your monitor's resolution, you might need to zoom out to see all the figures






1) Principal Component Analysis and ADMIXTURE Analysis for K = 6
https://i.imgur.com/BNlEt04.jpg

2) Admixture-f3(Yoruba-Mandenka, Basque-Iraqi; North African) and Runs of Homozygosity Analysis
https://i.imgur.com/NLRxIKo.jpg

3) Tested qpGraph Model and Proportions of Ancestral Components in North African Populations
https://i.imgur.com/2s3bJ70.jpg

4) Effective Population Size throughout Time and Pairwise Genetic Differences
https://i.imgur.com/WsENBn5.jpg
Supplemental Info:

https://i.imgur.com/wu95VMd.png

https://i.imgur.com/NSo3zY9.png

https://i.imgur.com/aCBtncb.png




https://i.imgur.com/cTPO3Y7.png



https://i.imgur.com/1Hxnszt.png

https://i.imgur.com/sbfSl0h.png

https://i.imgur.com/wBOb9OC.png

Paper PDF extract (https://drive.google.com/open?id=1pCFPFUTNhpfleQvKyw5FRnKSqx8WkwZN)

[Amhas]

This paper has 2 riffian berbers and 1 morisco.

[Milkyway]

We need more ancient genomes from North Africa. To date, we only have three Paleolithic samples from Morocco, which is too few to describe the genomic history of the region within the last 12,000 years IMHO. Far older remains have been found in the region, which might be partially related to present-day North Africans and/or West Africans. We also don't have Paleolithic genomes from NE Africa (such as Egypt or Lybia) which might tell a slightly different story. Prehistoric gene flow between N. Africa and Europe has apparently taken place, but how many times? Did it only involve populations from Iberia and Morocco or other Mediterranean regions as well?