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Open Access Highly Accessed Research article

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

Nourdin Harich1, Marta D Costa23, Verónica Fernandes23, Mostafa Kandil1, Joana B Pereira23, Nuno M Silva2 and Luísa Pereira24*

Author affiliations

1 Laboratoire d'Anthropogénétique, Départment de Biologie, Faculté des Sciences, Université Chouaïb Doukkali, El Jadida, Morocco

2 Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal

3 Institute of Integrative and Comparative Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK

4 Medical Faculty, University of Porto, Portugal

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Citation and License

BMC Evolutionary Biology 2010, 10:138  doi:10.1186/1471-2148-10-138

Published: 10 May 2010

Abstract

Background

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 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.

Results

The 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.

Conclusions

The 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.