The low incidence of E-M293 (0.8%) and A-M91 (0%) on the Comoros contrasts strongly with the frequency of these haplogroups in East African populations.
This is an interesting piece of evidence in support of the idea of very recent genetic changes in east Africa.
A comparison of the relative incidences of E-M78(V22), E-M123, G, J, L, Q and R on the Comoros with populations around the Arabian Sea shows greatest similarities with Southern Iran, and, to a lesser extent, Turkey.I have often noted that what you don't find in a population is often more informative about ancient history than what you do find, as it points towards -in the absence of a very small founding population- to its absence in the source populations. In the case of the Comoros, I note the absence of the R1b clade, which ties these islands with India and parts of the Middle East as the only R1b-less regions influenced by Caucasoids.
A possible source of the Northern Y-chromosomes is therefore the Shirazi traders from Southern Iran who established trading posts on the Comoros by 800YBP.
A trace of E-M78, in the form of E-V22 (0.5%) is also interesting, and certainly ties the Comoros with the interior of the Middle East where E-M78 is rare, rather than the more western regions where it is frequent.
The presence of 0.5% haplogroup I-P38 is also interesting, coupled with the absence of R1b: native Near Eastern haplogroup-I or European admixture: here are the I haplotypes for anyone interested in digging deeper into this:
DYS456 DYS389I DYS390 DYS389 II DYS458 DYS19 DYS385a DYS385b DYS393 DYS391 DYS439 DYS635 DYS392 Y-GATA-H4 DSY437 DYS438 DYS448
15 12 24 28 17 15 14 19 13 11 11 25 11 11 14 11 19
16 13 23 30 16 14 15 16 12 10 12 21 11 13 15 9 21
Feel free to leave a comment if you figure out something extra about these chromosomes.
as for the SE Asian component:
We found the O1 lineage (6%) in the Comoros sample, providing genetic evidence for an SEA influence ... All but one of the Comorian O1 chromosomes are O1a-M50There were also C* and K* lineages on the islands, which could also plausibly be SEA in origin. However note that these are C*(xC1-5) and K*(xLMNOPQRST).
European Journal of Human Genetics advance online publication 11 August 2010; doi: 10.1038/ejhg.2010.128
Genetic diversity on the Comoros Islands shows early seafaring as major determinant of human biocultural evolution in the Western Indian Ocean
Said Msaidie et al.
The Comoros Islands are situated off the coast of East Africa, at the northern entrance of the channel of Mozambique. Contemporary Comoros society displays linguistic, cultural and religious features that are indicators of interactions between African, Middle Eastern and Southeast Asian (SEA) populations. Influences came from the north, brought by the Arab and Persian traders whose maritime routes extended to Madagascar by 700–900 AD. Influences also came from the Far East, with the long-distance colonisation by Austronesian seafarers that reached Madagascar 1500 years ago. Indeed, strong genetic evidence for a SEA, but not a Middle Eastern, contribution has been found on Madagascar, but no genetic trace of either migration has been shown to exist in mainland Africa. Studying genetic diversity on the Comoros Islands could therefore provide new insights into human movement in the Indian Ocean. Here, we describe Y chromosomal and mitochondrial genetic variation in 577 Comorian islanders. We have defined 28 Y chromosomal and 9 mitochondrial lineages. We show the Comoros population to be a genetic mosaic, the result of tripartite gene flow from Africa, the Middle East and Southeast Asia. A distinctive profile of African haplogroups, shared with Madagascar, may be characteristic of coastal sub-Saharan East Africa. Finally, the absence of any maternal contribution from Western Eurasia strongly implicates male-dominated trade and religion as the drivers of gene flow from the North. The Comoros provides a first view of the genetic makeup of coastal East Africa.