An Iranian from 1800 BCE

While scourging through the Narasimhan supple, I found a sample that caught my eye. It clustered on a PCA with modern Iranians and on G25 distances, it had the lowest distances to modern Iranians; however, it was from the post-BMAC site of Sappali Tepe in Uzbekistan and dated to ~1800 BCE cal. 

The supplementary describes it as such.

BMAC_o2 (n=1): This individual has a significantly elevated proportion of ancestry related to

Central_Steppe_MLBA. We call this individual by the BMAC_o2 analysis label and the

Sappali_Tepe_BA_o split label.

• UZ-ST-010, Sappali Tepe (ST) 1975, 6, Grave 02-05 (I7493): Context date of 2000-1600

BCE. Genetically male.

Distance to: UZB_Sappali_Tepe_BA_o

0.03315719 Iranian_Zoroastrian
0.03528786 Iranian_Fars
0.04027134 Iranian_Persian_Shiraz
0.04254455 Azerbaijani_Dagestan
0.04405072 Ezid
0.04435116 Iranian_Mazandarani
0.04586352 Iranian_Lor

On a PCA, Sappali Tepe clusters with other Iranians as well, shifted a bit to the extreme end of the West Iranian Steppe % The rest of the Sappali Tepe site is regular post-BMAC and accordingly clusters with other BMAC (Gonur1) and post BMAC (Bustan BA) sites. So it's obvious this outlier has BMAC + Steppe ancestry. Not that out of the ordinary, right? Even TKM_IA has this mixture.

Target: UZB_Sappali_Tepe_BA_o:I7493
Distance: 4.9056% / 0.04905551
65.2 UZB_Sappali_Tepe_BA
34.8 RUS_Sintashta_MLBA

Poor distance, but where it gets interesting is when you add West Iranian farmer ancestry.  

Target: UZB_Sappali_Tepe_BA_o:I7493
Distance: 3.0157% / 0.03015733
48.2 IRN_Seh_Gabi_C
33.2 RUS_Sintashta_MLBA
18.6 UZB_Sappali_Tepe_BA

This is great, the distance improves a lot. This must mean this individual is a mix of West Iranian type farmers + early East Iranian (TKM_IA) type ancestry. Now, interestingly enough, this must mirror the actual process by which modern West Iranians came to be. Steppe pastoralists mix with Turan_BA (BMAC) type people and form a hybrid 50:50 ish population in the region surrounding modern Tajikistan. This population eventually comes down to the Iranian plateau and mixes with the native Elamite farmers to form modern West Iranians. 

So, let's model it with TKM_IA too, but first add in Indus Valley. 

Target: UZB_Sappali_Tepe_BA_o:I7493
Distance: 2.3048% / 0.02304809
57.2 IRN_Seh_Gabi_C
32.8 RUS_Sintashta_MLBA
10.0 IRN_Shahr_I_Sokhta_BA2

Modern Iranians likely received an additional wave of Levant_C or Anatolia_C that mixed with their Sehi_Gabi type pop, so might as well as try it with that too.

Target: UZB_Sappali_Tepe_BA_o
Distance: 2.1811% / 0.02181055
52.2 TKM_IA
26.6 IRN_Seh_Gabi_C
12.4 Levant_ISR_C
8.8 Indus(Sis2+Gonur)

Yep, way better fits. TKM_IA likely also absorbs nearby WSHG/ANE type ancestry.

Can we replicate this on qpAdm? Let's try. 

Uzbekistan_SappaliTepe_BA_o

Turkmenistan_IA.SG 49.2% ± 9.4

Iran_C_SehGabi 19.8% ± 9.5

Israel_C 20.1% ± 5.6

Indus 10.9% ± 7.3

p-value:  0.300

(Outgroups: Mbuti, EEHG, WEHG (Iron Gates), WSHG, ESHG, Han, Tianyuan, TurkeyN, IranN, Levant PPN, Iberomaurusian/Natufian (optional), CHG, MA1 (optional), Kostenki14 (optional))

This is pretty close to our G25 results. This would mean Sappali Tepe has around ~25% Sintashta ancestry, thus being a perfect fit to model modern Iranians with (who have quite a bit lower Sintashta).

By the way, I tried Anatolia_C and Rus_Maykop_Nosovko as sources too. Former gives quite decent fits on qpAdm and works equally well as a source, but drops TKM_IA to 40% ish. Latter is a poor source, but I decided to try it anyways as some outliers in Bronze Age Turan carry Caucasus ancestry (like the Dzharkutan outliers from Uzbekistan which are Caucasus + Steppe). 

I also tried out other IranN rich profiles such as Sarazm, Geokysur, Parkhai, Namazga as well. They give much poorer fits on G25 and qpAdm. Anyway, let's just do a Dstats run to see if there is indeed allele sharing b/w the two, and to what extent.

result:  Chimp.REF Uzbekistan_SappaliTepe_BA_o Anatolia_C   Israel_C     -0.0235    -4.133     -    7424   7781 153314 

Significant negative Z score, so it looks like Anatolia_C is actually preferred as the Chalcolithic source over Israel_C.  G25 shows the same, the fit improves when we use Anatolia_C. 

Regardless of the exact Chalco source, let's try and model Modern Iranians with the Sappali outlier.

Target	Distance		IRN_Seh_Gabi_C	IRN_Shahr_I_Sokhta_BA2	Levant_ISR_C	MNG_Slab_Grave_EIA_1	UZB_Sappali_Tepe_BA_o	Yoruba
Iranian_Bandari	0.02025044	•	26.6	20.8	0.8	0.0	48.8	3.0
Iranian_Fars	0.01639102	•	27.2	0.8	7.0	2.2	62.8	0.0
Parsi_India	0.01486118	•	10.8	29.2	13.4	0.8	45.8	0.0
Parsi_Pakistan	0.01436086	•	9.6	27.4	12.8	0.8	49.4	0.0
Iranian_Lor	0.01120472	•	35.8	0.0	10.8	1.2	52.2	0.0
Iranian_Mazandarani	0.01877939	•	44.8	3.4	0.0	0.0	51.8	0.0
Iranian_Persian_Shiraz	0.01724956	•	29.0	3.6	9.4	2.6	55.0	0.4
Iranian_Zoroastrian	0.01704363	•	22.4	0.0	6.6	0.0	71.0	0.0
Average	0.01626760	•	25.8	10.7	7.6	0.9	54.6	0.4

Very good fits. If Sappali is around 24-27% ish Steppe, then this gives Iranian Zoroastrians around 18-19% Steppe, which sounds just about right. So this individual from 1800 BCE Uzbekistan is indeed quite close to a modern West Iranian. 

His haplogroup is Q1b2, which is an India specific branch of Q1 (found in the Swat Valley Loebanr samples) and this kinda gives more evidence for the 10-11% Indus Valley ancestry in him. 

This individual is remarkably similar to another outlier from 1500 BCE Uzbekistan, who I discussed in my substack here. However, this outlier clusters with modern Indo-Aryans and contains the 3 way Steppe + Indus + Onge admix that characterizes modern Indians. The Sappali Tepe outlier contains the 3 way mix that characterizes modern Iranians: Steppe + BMAC + Iranian chalcolithic farmer. 

Now, we cannot be possibly sure what language this outlier spoke, but my bet is it was likely some form of early Iranian, thereby meaning the genepool that characterizes modern Indians and Iranians had already formed in Central Asia by 1600-1800 BCE.