The precursor of the Trojans

Who remembers kum4 from Omrak et al. 2016? I'm pretty sure now that this individual packs a lot of ancestry from the Pontic-Caspian (PC) steppe.

If so, that's a big deal, because her Chalcolithic (or Late Neolithic?) burial was located at Kumtepe. That is, in the same part of Anatolia as the later settlement of Troy, which may have been founded by early Anatolian speakers from Eastern Europe (see here).

The qpAdm mixture models below, featuring kum4 and the likely older kum6, also from Kumtepe, are based on qpfstats output. qpfstats is a new program from the David Reich Lab specifically designed to help analyze low coverage ancients (see here). And kum4 is certainly that.

TUR_Kumtepe_N_kum4
RUS_Progress_En 0.383±0.114
TUR_Barcin_N 0.617±0.114
chisq 7.868
tail prob 0.247957
Full output

TUR_Kumtepe_N_kum4
IRN_Seh_Gabi_C 0.325±0.150
TUR_Barcin_N 0.675±0.150
chisq 14.736
tail prob 0.0224096
Full output

TUR_Kumtepe_N_kum6
RUS_Progress_En 0.121±0.042
TUR_Barcin_N 0.879±0.042
chisq 21.790
tail prob 0.00132149
Full output

TUR_Kumtepe_N_kum6
IRN_Seh_Gabi_C 0.283±0.059
TUR_Barcin_N 0.717±0.059
chisq 6.289
tail prob 0.391566
Full output

Indeed, kum4 and kum6 offer just ~10,000 and ~100,000 "valid SNPs", respectively (see here). However, if nothing else, the results are clearly not random.

For one, because they fit the expected pattern, with the likely older individual lacking ancestry from the PC steppe (her model with RUS_Progress_En shows a weak statistical fit). Moreover, the qpAdm mixture ratios align almost perfectly with the results in my Principal Component Analysis (PCA) of ancient West Eurasian genetic variation. Coincidence?

See also...

Perhaps a hint of things to come

Perhaps a hint of things to come

It's still a mystery how the Hittites and other Anatolian speakers ended up in the Near East. However, the leading theory is that their ancestors migrated from the steppes of Eastern Europe to western Anatolia via the Balkans sometime during the Copper Age.

Consider the qpAdm mixture models below, made possible thanks to some of the ancient samples published recently along with Skourtanioti et al. 2020. The key ancients are described in a text file available here.

TUR_Barcin_C
AZE_Caucasus_lowlands_LN 0.471±0.094
RUS_Vonyuchka_En 0.148±0.040
TUR_Barcin_N 0.381±0.069
chisq 12.874
tail prob 0.116261
Full output

TUR_Barcin_C
RUS_Vonyuchka_En 0.107±0.029
TUR_Buyukkaya_EC 0.893±0.029
chisq 12.107
tail prob 0.207331
Full output

I'd say it's quite clear now that TUR_Barcin_C harbors minor ancestry from the Pontic-Caspian (PC) steppe. The reason this isn't widely accepted yet is because demonstrating it convincingly hasn't been possible without a proximate Anatolian ancestry source for TUR_Barcin_C, precisely like TUR_Buyukkaya_EC.

Admittedly, though, the statistical fits in my models aren't all that great. I suspect the problem lies with RUS_Vonyuchka_En, which is likely to be a rather poor stand in for the people who brought steppe ancestry, and possibly early Anatolian speech, to western Anatolia.

So let's see what happens when I try a more proximate reference for the steppe ancestry in TUR_Barcin_C. How about Yamnaya_BGR, an individual of mixed Balkan and steppe origin from what is now Bulgaria?

TUR_Barcin_C
AZE_Caucasus_lowlands_LN 0.518±0.075
TUR_Barcin_N 0.203±0.056
Yamnaya_BGR 0.279±0.067
chisq 10.602
tail prob 0.225269
Full output

TUR_Barcin_C
TUR_Buyukkaya_EC 0.749±0.058
Yamnaya_BGR 0.251±0.058
chisq 9.687
tail prob 0.376414
Full output

That's a little better. Unfortunately, the problem now is that the models are anachronistic, because TUR_Barcin_C is about a thousand years older than Yamnaya_BGR. Clearly, we need more Copper Age samples from the western edge of the PC steppe, the eastern Balkans, and especially northwestern Anatolia.

The Principal Component Analysis (PCA) below effectively illustrates why my qpAdm models work. It was produced with Global25 data using the Vahaduo PCA tools freely available here. Note that TUR_Barcin_C is shifted away from the essentially perfect cline formed by AZE_Caucasus_lowlands_LN, TUR_Barcin_N and TUR_Buyukkaya_EC towards samples from ancient Eastern Europe, including Yamnaya_BGR.

See also...

Steppe invaders in the Bronze Age Balkans