Haplogroup E1b1a1

Geographic distribution

Modern distributions of E1b1a1 are concentrated in western and central Africa. High frequencies are observed among populations in Nigeria, Cameroon, Benin, Togo and surrounding regions, extending eastward into parts of the Congo Basin and southward along key Bantu expansion corridors. Many Niger Congo speaking groups carry substantial proportions of E1b1a1 or its downstream branches. The lineage is also found in southeastern Africa, including in Mozambique, Zimbabwe and South Africa, where it reflects historical Bantu mediated migrations and admixture with local populations. Outside Africa, E1b1a1 appears in the Americas and the Caribbean in communities of African descent, particularly in Brazil, the United States and several island populations, as a direct consequence of the trans Atlantic slave trade. Its presence in these regions provides a genetic footprint of West and West Central African origins.

Ancient DNA

• Ancient DNA data for specific E1b1a1 lineages remain limited, largely because of preservation issues in tropical environments. However, Iron Age and later burials in southern and eastern Africa often carry downstream E1b1a lineages that phylogenetically fall within or close to the E1b1a1 radiation.
• Archaeological horizons associated with early agricultural and iron working cultures in West and Central Africa are chronologically consistent with the major Holocene expansion phase of E1b1a1, even when direct Y chromosome data are lacking.
• Patterns of internal diversity and coalescence times within E1b1a1 subclades support a model in which the lineage was already structured in West Africa before the onset of large scale Bantu movements and then participated in those later expansions.

Phylogeny & subclades

Within E1b1a, E1b1a1 forms a large subtree characterized by multiple downstream branches. Key derivative clades include groups defined by SNPs such as M191 itself, as well as further nodes including U174 and U175 when considered within the broader M2 context. Some taxonomic schemes place E-U174 and E-U175 further downstream under E1b1a1a1, but in practical terms these lineages form part of an interlinked radiation originating from the E1b1a1 ancestor. Internal branching times cluster in the early to mid Holocene, indicating that the diversification of E1b1a1 coincided with environmental amelioration after the last glacial maximum and with the emergence of early food producing economies in parts of West and Central Africa. The phylogeny shows a pattern of star like expansions typical of successful male lineages that experienced strong founder effects and social amplification.

• E1b1a1* (basal M191 lineages in West and Central Africa)
• E1b1a1a and related clusters that form the backbone of many Niger Congo speaking populations
• Subclades downstream of U174 and U175 that participate in Bantu associated expansions
• Numerous regional micro branches detected in high coverage sequencing studies of West and Central African populations

Notes & context

E1b1a1 is a key component of the genetic landscape that underpins the spread of Niger Congo languages and the population history of West and Central Africa. Its age and structure indicate that it arose among forager or early horticultural populations and only later became entangled with large scale Bantu expansions. Because many of its subclades show strong regional patterns, E1b1a1 is frequently used in population genetic studies that attempt to trace finer scale connections between West African source populations and descendant communities elsewhere in Africa and in the diaspora. The lineage exemplifies how a relatively ancient Pleistocene clade can become demographically dominant only during much later Holocene cultural transitions.

References & external links

• YFull YTree – Haplogroup E-M191
• Berniell-Lee et al. – Genetic and demographic impact of the Bantu expansion
• Cruciani et al. – Phylogeographic structure of E1b1a lineages