Asians returned to Africa or, at least that is what this paper says: Brief communication: mtDNA variation in North Cameroon: Lack of asian lineages and implications for back migration from Asia to sub‐Saharan Africa, by Valentina Coia Giovanni Destro‐Bisol Fabio Verginelli Cinzia Battaggia Ilaria Boschi Fulvio Cruciani Gabriella Spedini David Comas Francesc Calafell, first published: 13 May 2005, https://doi.org/10.1002/ajpa.20138.
The abstract is very clear:
"The hypervariable region‐1 and four nucleotide positions (10400, 10873, 12308, and 12705) of the coding region of mitochondrial DNA (mtDNA) were analyzed in 441 individuals belonging to eight populations (Daba, Fali, Fulbe, Mandara, Uldeme, Podokwo, Tali, and Tupuri) from North Cameroon and four populations (Bakaka, Bassa, Bamileke, and Ewondo) from South Cameroon. All mtDNAs were assigned to five haplogroups: three sub‐Saharan (L1, L2, and L3), one northern African (U6), and one European (U5). Our results contrast with the observed high frequencies of a Y‐chromosome haplogroup of probable Asian origin (R1*‐M173) in North Cameroon. As a first step toward a better understanding of the evident discrepancy between mtDNA and Y‐chromosome data, we propose two contrasting scenarios. The first one, here termed “migration and asymmetric admixture,” implies a back migration from Asia to North Cameroon of a population group carrying the haplotype R1*‐M173 at high frequency, and an admixture process restricted to migrant males. The second scenario, on the other hand, temed “divergent drift,” implies that modern populations of North Cameroon originated from a small population group which migrated from Asia to Africa and in which, through genetic drift, Y‐chromosome haplotype R1*‐M173 became predominant, whereas the Asian mtDNA haplogroups were lost."
In plain English, there is an Asian Y-chromosome haplogroup in North Cameroon, in equatorial Africa and the authors can't quite fit it into the Out of Africa theory because it is a male lineage and there are no Asian mtDNA groups in the region...
Did a band of men from Asia move across Africa to Cameroon without women? leaving their Y-chromosome DNA but no mtDNA... Or did genetic drift erase the invading group's women's mtDNA?. Why would this happen?
I think that the U haplogroup mtDNA is the key here... see the map below:
The map shows mtDNA haplo U distribution. Clearly an "into Africa" move.
This surely introgressed Neandertal DNA into Africans.
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