The trans-Saharan slave trade - clues from interpolation analyses and high-resolution characterization of mitochondrial DNA lineages

Nourdin Harich,Mostafa Kandil,Luísa Pereira,Marta D Costa,Joana B Pereira,Verónica Fernandes,Nuno M Silva

doi:10.1186/1471-2148-10-138

Nourdin Harich, Mostafa Kandil + Show 5 more

Open Access

https://doi.org/10.1186/1471-2148-10-138

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Abstract

BackgroundA proportion of 1/4 to 1/2 of North African female pool is made of typical sub-Saharan lineages, in higher frequencies as geographic proximity to sub-Saharan Africa increases. The Sahara was a strong geographical barrier against gene flow, at least since 5,000 years ago, when desertification affected a larger region, but the Arab trans-Saharan slave trade could have facilitate enormously this migration of lineages. Till now, the genetic consequences of these forced trans-Saharan movements of people have not been ascertained.ResultsThe distribution of the main L haplogroups in North Africa clearly reflects the known trans-Saharan slave routes: West is dominated by L1b, L2b, L2c, L2d, L3b and L3d; the Center by L3e and some L3f and L3w; the East by L0a, L3h, L3i, L3x and, in common with the Center, L3f and L3w; while, L2a is almost everywhere. Ages for the haplogroups observed in both sides of the Saharan desert testify the recent origin (holocenic) of these haplogroups in sub-Saharan Africa, claiming a recent introduction in North Africa, further strengthened by the no detection of local expansions.ConclusionsThe interpolation analyses and complete sequencing of present mtDNA sub-Saharan lineages observed in North Africa support the genetic impact of recent trans-Saharan migrations, namely the slave trade initiated by the Arab conquest of North Africa in the seventh century. Sub-Saharan people did not leave traces in the North African maternal gene pool for the time of its settlement, some 40,000 years ago.

Highlights

A proportion of 1/4 to 1/2 of North African female pool is made of typical sub-Saharan lineages, in higher frequencies as geographic proximity to sub-Saharan Africa increases
The subcharacterization of H-lineages observed in several North African populations revealed its affiliation within Iberian expanded lineages, after the Last-Glacial Maximum [6,7], being the same observed in Tuareg living in the Sahel [8]
The Near Eastern contribution to the pool of H lineages in North Africa was minimal, indicating that a pre-historic European lineage input occurred in elevated frequencies enriching the ancient Near Eastern background of North African populations mainly constituted by the low frequent haplogroups U6 and M1 [9]

Summary

Introduction

A proportion of 1/4 to 1/2 of North African female pool is made of typical sub-Saharan lineages, in higher frequencies as geographic proximity to sub-Saharan Africa increases. The characterization of the full mtDNA sequence is being used to investigate local events as the Chadic expansion from East Africa towards Chad Basin in the last 8,000 years [1] or historic movements as the diaspora of Jews [2,3], which could not be approached in previous more limited mtDNA surveys This approach is being applied to the long-enduring discussion about pre-historic migrations across the Mediterranean Sea, leading to exchange of lineages between Iberia and Maghreb [4,5]. The Near Eastern contribution to the pool of H lineages in North Africa was minimal, indicating that a pre-historic European lineage input occurred in elevated frequencies enriching the ancient Near Eastern background of North African populations mainly constituted by the low frequent haplogroups U6 and M1 [9]. It is known that a proportion of 1/4 to 1/2 of North African female pool is made of typical sub-Saharan lineages (designated as haplogroups L0-L6), in higher frequencies as geographic proximity to sub-Saharan Africa increases [4,5]

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