Recent admixture in Altaic populations: a legacy of Empire?

Continuing my experiments with ALDER, I took every single Altaic population publicly available, i.e., the following 25 populations:

Altai, Balkars_Y, Buryat, Chuvashs_16, Daur, Dolgan, Evenk_15, Hezhen, Kumyks_Y, Kyrgyz_Bishkek_Ho, Mongol, Mongola, Nogais_Y, Oroqen, Tu, Turkish_Aydin_Ho, Turkish_Istanbul_Ho, Turkish_Kayseri_Ho, Turkmens_Y, Turks, Tuva, Uygur, Uzbeks, Xibo, Yakut

I also took three West Eurasian populations unlikely to have historical East Asian admixture (French, French_Basque, and Sardinians), and three East Eurasian populations unlikely to have historical West Eurasian admixture (Dai, She, Miaozu). I merged all of the above in PLINK with a --geno 0.03 flag, and extracting SNPs present in the Rutgers recombination map for Illumina chips (a total of 524,822 SNPs).

I then ran ALDER for all 25 Altaic populations using any of the 3*3 West/East Eurasian reference pairs, or a total of 25*3*3= 225 runs. I retained only those 2-ref admixture analyses for which ALDER reported "success" with no warnings.

I then converted reported times to calendar dates: a generation of 29 years was assumed; lacking information about the age of the sampled individuals, I assumed that the "present" is 1980; finally, I report the earliest and latest -/+ limits of any confidence interval, as well as the median of all estimates.

The results can be seen below; for 11 of the 25 populations there was at least one test which was successful with no warnings. This does not mean that the other populations are unadmixed, but the following cases appear to be most "well-behaved":

Now, these appear to make excellent sense.

Of the Dolgans:

There also existed a group of Russian settlers on the River Heta, who, by the end of the 19th century, had become Dolganized and had gradually adopted the way of life of nomadic reindeer breeders. ... The tribes forming the nucleus of the Dolgans migrated from the banks of the River Lena at the end of the 17th century. One of the reasons for migration was the fact that Russian goods, flour, for instance, were coming to the Taimyr Peninsula by the boats on the Lena.

The 1770-1860AD range for the admixture appears to coincide with the period where the Dolgans came under Russian influence.

Of the Evenks:

The history of the Evenks' habitation can be traced in detail from the 17th century on. At that time the Evenks left several of their previous territories, for instance, the River Angara, when the Yakut, the Buryat and the Russians appeared in the province. The Evenks had especially bad relations with the Yakuts, who had settled in the river basin of the Lena in the 13th century. In the 18th and 19th centuries the Evenks living there adopted the Yakut language. In the Baikal area the Evenks began to speak the Buryat and the Mongolian languages, and even converted to lamaism. The southern Evenk -- the Manegir, the Birar, the Solon -- were influenced by the Manchu, Daur and Chinese cultures. The arable lands in Siberia were occupied by Russian settlers, migrating there in the 17th century, and those Evenks, living in the vicinity on the upper reaches of the Lena and near Baikal, were russified.

Again, the  1630-1800AD admixture range seems consistent with the time when Evenks came into contact with Russians.

Of the Nogais:

 In the first half of the 17th century a number of Nogay tribes were nomadic on the steppes between the Danube and the Caspian. The invasion of the warlike Kalmyks forced several of the Nogay tribes to leave their home steppes and withdraw to the foothills of the North Caucasus. By the River Kuban they met with the Cherkess.  In the Moscow chronicles from the 16th and 17th centuries there are several mentions of the Nogay, including the two Nogay Hordes, the Great and the Small. The former roamed beyond the River Volga, the latter somewhat to the west. Both had numerous military encounters with the Russians. In the 17th century some of the Nogay chiefs entered into an alliance with Moscow and fought at times together with the Russians against the Kabardians, the Kalmyks and peoples of Dagestan. 

 The 1610-1730AD range intersects the period when the Nogais settled in the North Caucasus and interacted with North Caucasians and Russians.

Not much needs to be said for the admixture signal in the Uygur, Uzbek, Kyrgyz, and Mongols which collectively ranges from 1260-1500AD. This was a period of Mongol power when Mongolian and Turkic speaking peoples assumed control over Central Asia and replaced to a great degree the previous inhabitants of the area.

The origin of the Balkars is less certain, because they are an old Turkic group that settled in the Caucasus, but the admixture (830-1220AD) date seems plausible. So does, of course, that of the Turks from Caesaria (990-1260AD) which parallels those of my recent experiment, and can be associated with the takeover of Anatolia following the Battle of Manzikert. Finally, I don't have a read explanation for the 11-12th century signal of admixture in the Siberian Altai and Buryat, but presumably it has something to do with the expansions of Altaic peoples around that time that were also felt in the west during this period; presumably, this involved some type of mixture with Caucasoid groups in Siberia.

The admixture dates are quite helpful in helping us better interpret other signals of admixture such as those of ADMIXTURE analyses (e.g., globe13). For example, the Dolgan have 13.1% North_European in that experiment, and the Altai have 13.2%, but apparently this occurred centuries apart and may have involved different groups of West Eurasian people.

In conclusion, ALDER seems to find some quite plausible dates for major admixture episodes in the history of Altaic populations that are compatible with fairly recent historical events.