August 16, 2010

Y chromosomes and mtDNA from Comoros islands

From the paper:

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.


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.
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 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-M50
There 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.



Zach said...

I was reading that Persians had settled the Eastern coast of Africa since the Sassanids.

I had dismissed it as being some of sort of historical boast but this gene study does seem to show the extent of their settlement.

I'm conditioned to think that most settlers/colonialists/explorers were invariably Western; good to know that Asiatics were in on the action as well :P

Also strange that the Shirazis never hopped over to Madagascar. Its like the Malays & Arabs were the main presence in the Indian Ocean but very rarely overlapped one another.

Either way its a fascinating history and something wroth exploring.

Andrew Lancaster said...

Dienekes writes:
"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."

Not sure what the point being made is here. E-V22 is found in the Middle East, Mediterranean, The Horn of Africa, Sudan and Egypt. So being in the Comoros does not seem that surprising? (It could be expected in most likely scenarios?)

E-V22 should be carefully distinguished from other forms of E-V78.

Best Regards

aargiedude said...

The haplotypes are absolutely riddled with errors. There are 7 R1b1b2 samples, all labeled as belonging to very different haplogroups, including E1b1a and E2b. The study claims no R1b1b2 was found. All 7 R1b1b2 have 393=13, aka European, while in contrast almost all R1b1b2 from Iran, Middle East, and the Indian sub-continent have 393=12.

Normally, when a mislabel occurs, the haplogroup is assigned to a nearby branch. Definitely not the case in this study. I think these mistakes must be due to clerical mislabeling of the data after the fact, rather than outright misinterpretation of the results.

They claim to have found 2 J*, which is believable overall but given the extreme errors in their study and the fact that these 2 J* samples have 438=9 and 438=10, and that coincidentally the other J samples are split evenly between J1 (438=10) and J2 (438=9) makes me think it's just another error. The supposed J* don't have a point mutation in DYS458, but neither do any of the J1 samples, despite that point mutations were noted for several samples, usually in DYS385.

This is one of the lousiest y-dna studies ever. None of the SNP results should be considered valid unless their haplotype certifies the SNP result. Fortunately, they didn't botch the haplotypes, except for the lack of point mutations in DYS458 in J1.

AdygheChabadi said... The World Haplogroup an Haplo-I subclade predictor says...for I-P38 haplotype #1
Haplogroups and probabilities are as follows:
J2-M205 =>28% Q-Cluster1 =>13% E3b-V22 =>12% R1a1-English =>10% Ix-S23 =>6% H =>6% R2-M124-Cluster-B =>5% Q-M242-Group2 =>4% I-P37.2 =>3% E3b =>3% J1-M267 =>3% I-M253 =>1% R1b-IrishIII =>1% G , G2 =>1% E3a =>1%

For I-P38 haplotype #2
Haplogroups and probabilities are as follows:
J2-M172 =>58% J2-M67 =>33% J2-M92 =>6% E3b-V12 =>2%

Whit Athey's Haplogroup Predictor predicts for I-P38 haplotype #1

Q with a fitness score of 36 and a probability of 97.6%...equal priors...and for other priors...strongly predicted Q with up 90% and up...

For I-P38 haplotype #2

Predicted as J2a1b with a fitness score of 57 and a probability of 86.5%...J2a1(xbh) with a fitness score of 52 and a probability of 13.0%, and J2a1h with a fitness score of 35 and a probability of 0.5%...all equal priors. All other priors are 90% and up for J2a1...

pconroy said...

Fascinating stuff!

So this is one of the possible stopover spots that Austronesians took on their way from South East Asia.

Were they trading with Egypt possibly? I've seen somewhere the theory that Bronze or at least Tin ore was possibly traded between South East Asia and Mesopotamia or Egypt - could this be the link??

More on sources of Tin here:

Unknown said...

I just noticed it on the Genetic Atlas Y-World frequencies

31% J (M304) Arabids
15% E1b1b1 (M35) Meditids
12% R1 (M173) Eurasids

similar to:

30% J (M304) Arabids
26% R1 (M173) Eurasids
8% E1b1b1 (M35) Meditids