Yaghnobi Tajiks: Preliminary Results May Reveal Iranian Plateau Affinity [Original Work]

Slipping under the radar of the genetic genealogy world is this paper by Elisabetta Cilli and her colleagues, which investigated the mitochondrial data of 62 individuals from Tajikistan's Yaghnobi population. [1]

The Yaghnobis are of interest given their geographical isolation and the East Iranic nature of their language. Living just northeast of the predominantly Persian (Dari) speaking capital, Dushanbe, Yaghnobi is a continuation of a fully agglutinative Soghdian dialect representing the sole survivor of this language following the Persianization of Central Asia in Medieval times [2]. Despite its' East Iranic vocabulary, Yaghnobi demonstrates several linguistic features (i.e. gender loss, past imperfective preservation from present stem of a verb) which separates it from those modern East Iranic languages immediately surrounding it. Furthering the uniqueness of the Yaghnobi language in this context is the unity it forms through these features with languages mostly spoken further west in the Iranian plateau (e.g. Persian, Gilaki, Kurdish dialects). [2]

Although the results are preliminary and lack any empirical data, Cilli et al. have discovered some interesting connections between the Yaghnobi and relevant populations. In summary, they found the following:

MDS Plot of Results

• 42 individuals used for the preliminary work belonged to only 19 distinct mtDNA haplotypes. Of these, 11 were distinct among the Yaghnobi.
• The Yaghnobi have less mtDNA genetic diversity than other Central Asian populations (0.930) and this is attributed to their geographical isolation and recent history of displacement by the U.S.S.R. in the 1970's for agricultural purposes, where a small group (300) returned and repopulated their original homelands.
• Intriguingly, the Yaghnobi shared all of the mutual haplotypes (8/19) with populations from Iran (e.g. Gilakis, Mazandaranis and Iranians from Tehran and Esfahan) instead of other Central Asian groups, including their Tajik compatriots.
• The Yaghnobi shared most of these mutual haplotypes with Gilakis, Kurmanji Kurds and Avars from the Caucasus (4 each).
• However, owing to their predominantly distinct mtDNA character, the Yaghnobi are clear outliers from the general zone occupied by the reference groups. 

My critique and interpretation of these results are as follows:

• At least two instances of genetic drift occurring (founder effect via geographic isolation, bottleneck due to Soviet relocation) is likely responsible for the decreased mtDNA diversity. Thus, it is clearly simply a reflection of their environment.
• As a result of the Soviet relocation, it may be useful to determine whether results from the displaced parent population match what has been stated here. This is quite possible given the relocations occurred just over one generation ago (~40 years).
• It is difficult to criticise the decision to test 62 individuals and the utilisation of 42 haplotypes, given the Yaghnobi population in their homeland between 2007-9 only numbered approximately 500. Approximately 8% of the entire Yaghnobi population was therefore analysed here, which is a generous frequency given the amount of attention the region has received.
• The MDS plot would have benefited from the inclusion of populations in Europe, Southwest Asia and South Asia to comprehensively flesh out the position of Yaghnobis in Eurasia.
• Accepting that this is a preliminary investigation, it would still have been pleasing to see some raw data published. Aside from confirming that some/one Yaghnobi matched the Cambridge Reference Sequence (CRS, thus Haplogroup H2a2a which happened to be found in all the populations tested), there is no indication as to what the other mutations looked like. Or, for that matter, what mtDNA haplogroups were even present!

Correlation with Y-Chromosomal Data?

The Yaghnobi have been studied at least one other time through their inclusion in Dr. Spencer Wells et al.'s seminal piece The Eurasian heartland: a continental perspective on Y-chromosome diversity. The breakdown of their Y-Chromosomal SNP data (n=31) is as follows: [3]

3% C-M130(xC3a3-M48)

32% J2-M172

Y-SNP clustering reveals Yaghnobis sit near SE Europe and the Near-East

3% K-M9(xO-M175, O3-M122, O1a-M119, O2a1-M95, N1c1-M46) (possibly parahaplogroup such as K*-M9)
10% L-M20
3% P-M45 (xQ1a1-M120, Q1a3a1-M3, R2a-M124)
32% R1-M173 (likely R1b1a1-M73 or R1b1a2-M269)
16% R1a1a-M17(xR1a-M87, private marker)

Despite the double genetic drift undoubtedly affecting the frequencies, it is worth pointing out that the Yaghnobi presented with a broadly similar Y-DNA spectrum as Iran, where J2-M172, L-M20, R1-M173 and R1a1a-M17 (including subclades) comprise approximately 53% of the national average (refer to Grugni et al. analysis). 

This comparison should be taken with a grain of salt given the Iranian national average also comprises non-Iranic-speaking ethnic groups, the Wells Yaghnobi data does not present with thorough downstream Y-SNP evidence, the sample size is contentious and at least two contributors of a founder effect exist. However, that the Yaghnobi appear rich in J2, L and R is certainly reminiscent of Iranic-speaking populations in the region.


Conclusions

The Yaghnobi are an exceedingly interesting population whose overall parental markers seem to support a connection with populations further west than one would anticipate.

Despite the misgivings of all the data concerning them to date, the mtDNA similarity does corroborate specific linguistic features between the Yaghnobi language with those in the Iranian plateau, such as Kurdish or Persian.

If the data holds up in future investigations, it certainly calls to question whether the proposed model of linguistic inheritance exclusively down the parental line (as represented by Y-DNA data) is entirely correct given this connection.

How the Yaghnobi came to display the markers within them whilst speaking an East Iranic dialect with traits akin to those found in West Iranic languages is an intriguing question. One possible scenario is that the Yaghnobi are partly descended from ancient Iranians from the Iranian plateau during the Achaemanid era. This would also account for the linguistic commonalities noted in current literature.

Time (with the assistance of more mtDNA, Y-DNA and auDNA) will help us understand what happened in Central Asia during the formative period that was the Indo-Iranian migrations.



Reference

1. Cilli E, Delaini P, Costazza B, Giacomello L, Panaino A, Gruppioni G. Ethno-anthropological and genetic study of the Yaghnobis;an isolated community in Central Asia. A preliminary study. J Anthropol Sci. 2011;89:189-94.

2. Windfuhr, G. The Iranian Languages. 1st ed. Routledge Language Family Series. 2009.

3. Wells RS, Yuldasheva N, Ruzibakiev R, Underhill PA, Evseeva I, Blue-Smith J. The Eurasian heartland: a continental perspective on Y-chromosome diversity. Proc Natl Acad Sci U S A. 28;98:10244-9. 2001.

Interpreting New Iranian Y-Chromosomal Data (Grugni et al.) [Review]

Introduction

A new study on Iranian Y-Chromosomes released just yesterday has, to my satisfaction, adequately sampled every major ethno-linguistic group as well as determining inter-provincial variation between them. Grugni et al. sampled 938 unrelated Iranian men from 15 ethnic groups (including Assyrians, Zoroastrians and Turkmen) in 14 provinces across the country.


Abstract

"Knowledge of high resolution Y-chromosome haplogroup diversification within Iran provides important geographic context regarding the spread and compartmentalization of male lineages in the Middle East and southwestern Asia. At present, the Iranian population is characterized by an extraordinary mix of different ethnic groups speaking a variety of Indo-Iranian, Semitic and Turkic languages. Despite these features, only few studies have investigated the multiethnic components of the Iranian gene pool. In this survey 938 Iranian male DNAs belonging to 15 ethnic groups from 14 Iranian provinces were analyzed for 84 Y-chromosome biallelic markers and 10 STRs. The results show an autochthonous but non-homogeneous ancient background mainly composed by J2a sub-clades with different external contributions. The phylogeography of the main haplogroups allowed identifying post-glacial and Neolithic expansions toward western Eurasia but also recent movements towards the Iranian region from western Eurasia (R1b-L23), Central Asia (Q-M25), Asia Minor (J2a-M92) and southern Mesopotamia (J1-Page08). In spite of the presence of important geographic barriers (Zagros and Alborz mountain ranges, and the Dasht-e Kavir and Dash-e Lut deserts) which may have limited gene flow, AMOVA analysis revealed that language, in addition to geography, has played an important role in shaping the nowadays Iranian gene pool. Overall, this study provides a portrait of the Y-chromosomal variation in Iran, useful for depicting a more comprehensive history of the peoples of this area as well as for reconstructing ancient migration routes. In addition, our results evidence the important role of the Iranian plateau as source and recipient of gene flow between culturally and genetically distinct populations."

[PDF]


Interpretation of Results

Iranian Y-SNP Frequencies

Data from the original study can be found opposite. In addition, several contour maps showing the frequency of select Y-DNA Haplogroups found across the country are shown along the right. Armenians, Zoroastrians and Assyrians from Tehran, as well as Afro-Iranians from Hormozgan province, are excluded. Note that updated ISOGG nomenclature was applied wherever deemed appropriate (refer to SNP's for clarification of status). Frequency ranges shown on maps are from 0-100%. Please note the maps are only intended to depict general trends rather than specific figures. Refer to the figures from the study (above) for these.

- Consistent with anthropological data and historical records from South Iran, the Y-DNA Haplogroups with frequencies greater in Africa than Eurasia (B-M60 and E2-M75) peak in Hormozgan province. 

- Over half a dozen para-Haplogroups (C*-M216, F*-M89, H*-M69, IJ*-M429, J2*-M172, L*-M61, NO*-LLY22g, Q1*-P36.2 and R*-M207) were found scattered across Iran. Although the presence of para-Haplogroups within a region are often taken as an indicator of a lineage's antiquity there, both their consistency and correspondence with downstream younger clades must be considered before such a conclusion is made. As such, I do not consider H*-M69, NO*-LLY22g or C*-M216's presence in this cohort to indicate anything other than Iran's position as a geographic crossroad. The remaining ones (particularly J2*-M172, L*-M61 and R*-M207) require further investigation to elucidate whether Iran does stake the claim to the origins of each.

- Further to the above, it is likely that the R*-M207 reported in this paper is in fact R2*-M479 based on the dated SNP array used.

- C5-M356 makes a sporadic appearance across Iran. A mysterious clade with a spotty distribution across much of Eurasia. In the region, it is more commonly associated with the Indian Subcontinent.

Iranian J1c3-PAGE08

- Haplogroup G makes a strong appearance with, in my opinion, enough clade diversity to validate an origin in Iran or a close-by region. This is partially supported by its' presence in every ethnic group, albeit through different subclades.

- Although IJ*-M429 has finally been found, Grugni et al.'s decision not to publish STR data does not give us the means to determine if the two Mazandarani and Persian men are in fact related within a genealogical timeframe. The significance of this find in Iran will have to remain pending.

- The lacklustre SNP definition in the Y-DNA I found in Iran (Gilaki, Bandari, Kurdish and Armenian populations between I1-M253 and I2-M438) dissuades strong conclusions regarding the development of I-M170 relative to IJ*-M429's discovery. The lack of STR's prevents us from ascertaining whether these are recent contributions from Europe or not, or whether there is any European connection to begin with.

- Both the frequency and subclade diversity of Haplogroup J2-M172 (as well as the presence of J2*-M172 and J2a*-M410 across the country) makes Iran a strong candidate for the origin of this lineage.

- The strong presence of J1c3-PAGE08 is one of the surprising finds of this study. With an absence only amongst Assyrians from Azarbaijan province and a peak in Khuzestani Arabs (31.6%), I speculate this is an early Near-Eastern pastoralist nomad marker that is only accentuated in Khuzestani Arabs because the L147.1 marker (J1c3d), which is commonly associated with the expansion of Semitic languages (particularly Arabic in literature) was not tested here. Otherwise, it would be difficult to reconcile medieval Arabic admixture among Iran's Zoroastrians being comparable (and often greater) than Azeris, for instance, as Azerbaijan hosted Arab garrisons following the Sassanid collapse.

- Haplogroup Q presents with a very distorted picture. 42.6% of Turkmens belonging to Q1a2-M25 is not in agreement with Wells et al.'s The Eurasian Heartland: A continental perspective on Y-chromosome diversity, where Haplogroups J, N, R1a and R1b predominated, suggesting either an extensive Founder effect has taken place (i.e. regionalisation of certain branches from a common Oghuz Turk pool) or the Golestani Turkmen values have experienced a more generic form of genetic drift.
On the matter of Turkic affinities, Azeri's from Azarbaijan province have greater subclade variation than all other ethnic groups. However, the total frequency is either comparable (or less) than Persians nationwide. As it stands, if one were to presume Haplogroup Q in Iran was of Turkic origins, it would appear their contribution to the Persian and Azeri genepools is comparable despite linguistic differences. Although more data would certainly flesh this matter out, this diversity combined with the presence of N-M216 among Iran's Azeri population certainly gives a genetic basis for their linguistic heritage.

- Haplogroup R1a1a-M17 is regularly found at frequencies greater than 15% across Iran, contrary to the assertion made by Dr. Wells one decade ago regarding the limited samples he obtained, again from The Eurasian Heartland: A continental perspective on Y-chromosome diversity ;

Iranian G2a-P15

"Intriguingly, the population of present-day Iran, speaking a major Indo-European language (Farsi), appears to have had little genetic influence from the M17-carrying Indo-Iranians."

It is somewhat ironic, however, to note that the Persians from Fars province presented one of the lowest R1a1a-M17 frequencies observed in this study. Whether sampling chance is an issue here, or the sparsity of M17 is indeed a reality, is an open question.

- The presence of both R1a1-SRY1532.2 (shown as R1a* due to old nomenclature) and R1b*-M343 repeat the presence of these para-Haplogroups in the region, indicating West Asia was from whence Haplogroup R1-M173 began differentiating into the two primary subclades we see today in Eurasia.

- Haplogroup R1b1a2a-L23 is more frequent in the north and west of the country, which (together with its' presence in the furthest southern and eastern poles at ~3%) suggests it likely moved in an overall south-easterly direction via diffusion, probably during the Neolithic.

- The distribution of Haplogroup R2a-M124 is, much like C5-M356, irregular. Contrary to what is shown in Haber et al.'s research, R2a is not more common in the east of the country. Instead, it can be found amongst Esfahani Persians at a frequency of 9.1%. That Iran's R2a frequency achieves its' peak in the centre of the country is reminiscent of Sahoo et al.'s A prehistory of Indian Y chromosomes: Evaluating demic diffusion scenarios;

The sensationalist question of the hour; what accounts for the spike in R2a-M124 that has been picked up in Central Iran for the past half decade?

- Finally, Haplogroup T-M70 enjoys a frequency of 10.1% amongst Assyrians from Azarbaijan province, whilst also being more common among Persians across the country and Iranians from the western periphery of the country (Azeris and Kurds). This would suggest, therefore, an at least passive but deep association with ancient Near-Eastern cultures.

Criticisms of Paper

Despite the rich sampling pool, I have several immediate criticisms;

Iranian J1-M267

• There are some issues with the sampling strategy employed by this paper. For instance, the Assyrians (Christian non-Arab Semitic-speaking minority) are represented by 39 men, although Persians from Esfahan (a major Iranian city) are by 11 only. 
• Inadequate haplotype data has been released; the only offering is 8-STR's from select lineages (e.g. J1*-M267) which were used for variance analysis.
• Furthermore, a maximum of 10 Y-STR's were analysed, rendering some of their variance calculations questionable at such a low resolution. This also does away with the possibility of MRCA and intra-subclade age calculations.
• Grugni et al. have approached Haplogroup R1a1a-M17 in a similar vein to past studies (e.g. Haber et al., see Showcasing of Y-DNA Variation Among Afghan Ethnic Groups) by not referring to current data concerning the structure of R1a1a. As with Haber et al., R1a1a-M458 is taken as the "European" strain, despite research undertaken by the R1a1a and Subclades Y-DNA Project revealing the apparent schism between the upstream Z283 and Z93 SNP's being far more informative in this regard.
• Haplogroup R1b1a2*-L23 is considered as a "West Eurasian" paternal contribution to the Iranian plateau rather than the possibility it may have originated within or in proximity to the country's western zone. 
• As shown in Interpretation of Results, Grugni et al.'s use of dated nomenclature poses problems for those who may not be intimately familiar with recent Y-SNP Tree changes by ISOGG.

Acknowledgements

Map of Iran courtesy of D-Maps.com.