Y DNA
According to
Y chromosome studies by Sanchez et al. (2005) and Cruciani et al. (2004), the Somalis are paternally closely related to certain Ethiopian groups, particularly
Cushytic speakers:
[67][68]
"The data suggest that the male Somali population is a branch of the East African population − closely related to the
Oromos in Ethiopia and North Kenya − with predominant E3b1 [now "
E1b1b1"] cluster lineages... and that the Somali male population has approximately 15%
Y chromosomes from
Eurasia and approximately 5% from
sub-Saharan Africa."
[67]
Besides comprising the majority of the Y DNA in Somalis, the
E1b1b1a (formerly E3b1a)
haplogroup also makes up a significant proportion of the paternal DNA of Ethiopians,
Sudanese,
Egyptians,
Berbers,
North African Arabs, as well as many
Mediterranean and
Balkan Europeans.
[68][69] The M78 subclade of E1b1b is found in about 77% of Somali males,
[67] which, according to Cruciani et al. (2007), may represent the traces of an ancient migration into the Horn of Africa from
Egypt/
Libya.
[70] After haplogroup E1b1b, the second most frequently occurring
Y DNA haplogroup among Somalis is the Eurasian
haplogroup T (M70),
[71] which is found in slightly more than 10% of Somali males. Haplogroup T, like haplogroup E1b1b, is also typically found among populations of Northeast Africa, North Africa, the
Near East and the Mediterranean.
[72][73]
mtDNA
According to
mtDNA studies by Holden (2005) and Richards et al. (2006), a significant proportion of the maternal lineages of Somalis consists of the
M1 haplogroup,
[74][75] which is common among
Ethiopians and North Africans, particularly
Egyptians and
Algerians.
[76][77] M1 is believed to have originated in Asia,
[78] where its parent M clade represents the majority of mtDNA lineages
[79] (particularly in
India).
[80] This haplogroup is also thought to possibly correlate with the Afro-Asiatic language family:
[75]
"We analysed mtDNA variation in ~250 persons from Libya, Somalia, and Congo/Zambia, as representatives of the three regions of interest. Our initial results indicate a sharp cline in M1 frequencies that generally does not extend into sub-Saharan Africa. While our North and especially East African samples contained frequencies of M1 over 20%, our sub-Saharan samples consisted almost entirely of the L1 or L2 haplogroups only. In addition, there existed a significant amount of homogeneity within the M1 haplogroup. This sharp cline indicates a history of little admixture between these regions. This could imply a more recent ancestry for M1 in Africa, as older lineages are more diverse and widespread by nature, and may be an indication of a back-migration into Africa from the Middle East."
[75]
Another mtDNA study indicates that:
"Somali, as a representative East African population, seem to have experienced a detectable amount of Caucasoid maternal influence... the proportion
m of Caucasoid lineages in the Somali is
m = 0.46 [46%]... Our results agree with the hypothesis of a maternal influence of Caucasoid lineages in East Africa, although its contribution seems to be higher than previously reported in mtDNA studies."
[81]
Overall, these genetic studies conclude that Somalis and their fellow Ethiopian and Eritrean Northeast African populations represent a unique and distinct biological group on the continent:
[82][83]
"The most distinct separation is between African and non-African populations. The northeastern-African -- that is, the Ethiopian and Somali -- populations are located centrally between sub-Saharan African and non-African populations... The fact that the Ethiopians and Somalis have a subset of the sub-Saharan African haplotype diversity -- and that the non-African populations have a subset of the diversity present in Ethiopians and Somalis -- makes simple-admixture models less likely; rather, these observations support the hypothesis proposed by other nuclear-genetic studies (Tishkoff et al. 1996a, 1998a, 1998b; Kidd et al. 1998) -- that populations in northeastern Africa may have diverged from those in the rest of sub-Saharan Africa early in the history of modern African populations and that a subset of this northeastern-African population migrated out of Africa and populated the rest of the globe. These conclusions are supported by recent mtDNA analysis (Quintana-Murci et al. 1999)."
[83]
HLA antigens
The analysis of
HLA antigens has also helped clarify the possible background of the Somali people, as the distribution of haplotype frequencies vary among population groups.
[84] According to Mohamoud et al. (2006):
[85]
"HLA antigens of the Somali population are not categorised as well as those of other international ethnic groups. We analysed the HLA antigens of 76 unrelated Somalis who lived in the west of England. HLA -A, -B, -C and DRB1 typing was performed by polymerase chain reaction using sequence-specific oligonucleotide probes (PCR-SSOP) at a low-intermediate resolution level. Phenotype frequency, gene frequency and haplotype frequency were used to study the relationship between Somalis and other relevant populations. The antigens with highest frequencies were HLA -A1, A2, and A30; B7, B51 and B39; Cw7, Cw16, Cw17, Cw15 and Cw18; DR 13, DR17, DR8 and DR1. HLA haplotypes with high significance and characteristics of the Somali population are B7-Cw7, B39-Cw12, B51-Cw16, B57-Cw18. The result of HLA class I and class II antigen frequencies show that the Somali population appear more similar to Arab or Caucasoid than to African populations. The results are consistent with hypothesis, supported by cultural and historical evidence, of common origin of the Somali population."
[85]