Mitochondrial DNA (mtDNA)
Haplogroup L2 (dubbed "Clan Lingaire" by
Professor Sykes at Oxford
Ancestors) is characterized by the RFLP motif +3592 HpaI,
+10394 DdeI, −10871 MnlI, +16390 HinfI/−16390 AvaII, and by
the HVS-I motif 16223-16278-16390 (Chen et al. 1995,
Watson et al. 1997;
Quintana-Murci et al. 1999;
Alves-Silva et al. 2000;
Pereira et al. 2001).
L2 is commonly subdivided into four main sub-clades - L2a
through L2d (Chen et al. 2000;
Pereira et al. 2001;
Torroni et al. 2001;
Salas et al. 2002;
Rosa et al. 2004).
The four L2 sub-clades display
different geographic/ethnic distributions. L2a, the most
common clade (62% of the total L2), is the only one widespread
all over Africa. L2a may be subdivided into two major
widespread subsets by the 16309 mutation (HVS-I). The derived
form at 16309 appears to be more concentrated in western
Africa, but distribution studies are hampered by likely
reversions at this position. L2b and L2c are
virtually absent in eastern Africans and rare in southern
Africans, but are common in some Senegalese populations. The
fourth, newly-defined clade, L2d, is rather rare, but appears
to be mainly restricted to western Africa.
(Torroni et al. 2001).
Origin of L2a
It is difficult to trace the
origin of haplogroup L2a with any confidence. The deepest part
of L2a is most common in East Africa. However, the diversity
and TMRCA (Time to the Most Recent Common Ancestor) are similar in East (61,250 [SE 13,500] years) and
West (54,100 [SE 17,087] years) Africa. The diversity
accumulated separately in East and West Africa, estimated from
the main shared founder types (and disregarding the
possibility of subsequent gene flow), is again similar in the
two regions, at ~14,000 years (14,100 years [SE 5,100], and
13,800 years [SE 4,700], respectively), suggesting a
separation shortly after the Last Glacial Maximum (LGM). An
easterly origin for L2a also faces the following difficulties:
that the other subclades of L2 (L2b, L2c, and L2d) have a
clear western distribution, and that L2d diverges earlier in
the mtDNA phylogeny than L2a (Torroni et al. 2001).
A possible solution would be an origin for L2a somewhere
between east and west, followed by dispersals in both
directions along the Sahel corridor. Thus, it may have become
prevalent somewhere in north Central Africa, spreading
both east and west along the Sahel belt ~20,000 years ago at
the peak of the LGM (or somewhat earlier). (Salas et al.
A two-dimension plot based on the correspondence and phylogeographic analyses of absolute L and M1 haplogroup
frequencies of west, east, central, southwest and southeast
African populations, also places L2a squarely between east and
northwest Africa. [Plaza, et al. 2004
L2a is the most commonly
observed cluster (18.8%) among African Americans (Allard et
It is particularly abundant in the Kanembou (38% of the
sample), but is also relatively frequent in nomadic Arabs
(33%). [Cerny et al.
L2a can be further divided into L2a1, harboring the transition
at 16309 (Salas et al. 2002).
The most extensive pan-African haplotype (16189 16192 16223
16278 16294 16309 16390) is in the L2a1 haplogroup. This
sequence is observed in West Africa among the Malinke, Wolof,
and others; in North Africa among the Maure, Hausa, Fulbe, and others; in
Central Africa among the Bamileke, Fali, and others; in South Africa
among the Khoisan family including the Khwe and Bantu
speakers; and in East Africa among the Kikuyu. Closely related
variants are observed among the Tuareg in North and West
Africa and among the East African Dinka and Somali. (Ely et. al. 2006;
Watson et al. 1997).
For more on this specific haplotype, click HERE.
Two L2a sub-clusters, L2a1a
(defined by a substitution at np 16286 and a coding-region
marker at np 3918), and L2a1b, are well represented in
southeastern Africans. (Pereira et al. 2001;
Salas et al. 2002).
In the north, most Ethiopian L2a1 sequences share mutations at nps 16189 and
16309, however a minor portion, L2a1c, shares mutations at nps
16209, 16301, and 16354. (Kivisild et al. 2004).