April 13, 2015

Haplogroup G1, Y-chromosome mutation rate and migrations of Iranic speakers

The origin of Iranian speakers is a big puzzle as in ancient times there were two quite different groups of such speakers: nomadic steppe people such as Scythians and settled farmers such as Persians and Medes.

I am guessing that the story of Iranian origins will only be solved in correlation to their Indo-Aryan brethren and their more distant Indo-European relations.

Clearly, G1 cannot be Proto-Indo-European as it has a rather limited distribution in Eurasia, but it could very well have been a marker of a subset of Indo-Europeans. If it was present in ancestral Iranians, then this would geographically constrain the places where ancestral Iranians were formed.

PLoS ONE 10(4): e0122968. doi:10.1371/journal.pone.0122968

Deep Phylogenetic Analysis of Haplogroup G1 Provides Estimates of SNP and STR Mutation Rates on the Human Y-Chromosome and Reveals Migrations of Iranic Speakers

Oleg Balanovsky et al.

Y-chromosomal haplogroup G1 is a minor component of the overall gene pool of South-West and Central Asia but reaches up to 80% frequency in some populations scattered within this area. We have genotyped the G1-defining marker M285 in 27 Eurasian populations (n= 5,346), analyzed 367 M285-positive samples using 17 Y-STRs, and sequenced ~11 Mb of the Y-chromosome in 20 of these samples to an average coverage of 67X. This allowed detailed phylogenetic reconstruction. We identified five branches, all with high geographical specificity: G1-L1323 in Kazakhs, the closely related G1-GG1 in Mongols, G1-GG265 in Armenians and its distant brother clade G1-GG162 in Bashkirs, and G1-GG362 in West Indians. The haplotype diversity, which decreased from West Iran to Central Asia, allows us to hypothesize that this rare haplogroup could have been carried by the expansion of Iranic speakers northwards to the Eurasian steppe and via founder effects became a predominant genetic component of some populations, including the Argyn tribe of the Kazakhs. The remarkable agreement between genetic and genealogical trees of Argyns allowed us to calibrate the molecular clock using a historical date (1405 AD) of the most recent common genealogical ancestor. The mutation rate for Y-chromosomal sequence data obtained was 0.78×10-9 per bp per year, falling within the range of published rates. The mutation rate for Y-chromosomal STRs was 0.0022 per locus per generation, very close to the so-called genealogical rate. The “clan-based” approach to estimating the mutation rate provides a third, middle way between direct farther-to-son comparisons and using archeologically known migrations, whose dates are subject to revision and of uncertain relationship to genetic events.



LivoniaG said...

There is a remarkable film from 1925 called Grass. It follows the annual Bakhtiari migration in the southwest of modern Iran. Whatever its flaws, it does illustrate that "pastoralist" lifestyle could have developed in the Zagros mountains well before it moved to the steppes. One interesting part is the crossing of the Karun River by maybe a hundred thousand cattle. Another is the Anatolian hunter.

A shortened version of the film is here:

Unknown said...

As an observer only, my limited exposure in Eastern Afghanistan (2010-2011) was that there is no Kazakh presence, or limited at best. Other than Nuristani, the obvious Dari speakers were Tajik, Uzbek and Hazara, and many were bilingual in Pashto. Cultural vs ethnic preferences would be obvious outlyers considering that even with Iran, the "majority' Azeri-Persians, though having an Azeri background are culturally and linguistically Persian through their 2 centureis permanence in the country. I amnot deny the results of the study but perhaps the location of the samples were to that point of reference only.

eurologist said...

"The “clan-based” approach to estimating the mutation rate provides a third, middle way between direct farther-to-son comparisons and using archeologically known migrations, whose dates are subject to revision and of uncertain relationship to genetic events. "

They conveniently forgot about the most reliable of all: ancient DNA.

Also, as I have mentioned before, I strongly suspect mutation rates to "slow down" with age of method/ sample. And we are quite near experimental tests (planned or accidental) showing whether the effective mutation rate is time-dependent.

Ricardo Costa de Oliveira said...

Some Iranic G1 speakers could easily be Proto-Indo-European just like we have some basal types of J1 and J2 clearly associated with ancient and modern Iranic speakers. Let's remember the Proto-Turkic, the Proto-Afroasiatic and Proto-Semitic, the Proto-Uralic, they were all originally spoken in some original core areas and expanded to distant areas and new frontiers to give differentiated protolanguages. The modern frontiers incorporated and assimilated new populations and new derived haplogroups quite different from the original speakers and the basal founders. In the case of the J haplogroup and specially in the ancient Iranian J1 types we only need to investigate the basal Y full sequences of the first Northern Iranian basal J1 branches to understand the association with the same Iranian maps of the G1 frequences and concentrations.

Ned said...

I do hope 'West Indian' is a mistake for 'Western Indian'! I'm not sure that Central asians helped in the settlement of the West Indies!

Anonymous said...

"and G1-GG362 in West Indians"

if anyone was wondering, they mean people from the western part of India and not Caribbeans...

LivoniaG said...

This is actually a remarkable piece of research.

A key question is how the pastoralist economies got to the steppes. If it came along with domesticated animals, than it makes it possible that Indo-European languages also came along with it. This is the basic premise of any flavor of the Anatolian Theory of IE origin.

Steppe advocates of IE origins of course have worked hard to say that the Neolithic in Armenia, Anatolia and Iran did not include pastoralism. You can see some of the evidence evaluated in Daniel Potts' "Nomadism in Iran: From Antiquity to the Modern Era."

If there were herds of cattle, of course, one would think that pasture would dictate a transient steppes-style lifestyle right from the start. And since the archaeology as a whole is pretty light, the argument is about the lack of evidence more than the logic.

For a Russian sponsored project to essentially endorse the Anatolian theory appears to be pretty brave.

"Much higher STR variation in the west part of the Iranian-Armenian plateau makes the mountain homeland a more probable candidate. This conclusion fits the Anatolian theory of Indo-European origins, and the pattern of STR diversity (Fig 4) fits especially well."

Fanty said...

Blame Columbus for this name desaster..
He was sure to be on islands close to the coast of India.

He wondered why they are so primitiv as rumors said, India is wealthy and highly developed. But he definately did not know the phenotypes common in India or he would have known that these people are not "Indians".

Kurti said...

@Unknoen. Pastroalism started in what is nowadays known as Kurdistan. But most likely around the Zagros mountains there is no denying there. I have been advocating an Zagros/Albruz Mountain-North Mesopotamia origin of Indo European for a long time.

Pneumatikon said...

BOO-yah. I posted my latest "Romans are from Crete" video last night, and JUST FOUND this posting. I specifically laughed off the Steppe origin of the Iranian languages.