Friday, August 19, 2016

How things are looking so far

As David's recently pointed out, it does seem as though the old fateful triangle still remains:

Most West Eurasian populations still look like they're mostly, on a basal level, divvied up between a Basal Eurasian rich component (rather similar to the old "ENF" cluster), Ancient North Eurasian-related ancestry and Western European Hunter-Gatherer/Villabruna-cluster-related ancestry.

It seems that, in this set-up, the main distinction between groups such as Neolithic Iranians (alongside Caucasus Hunter-Gatherers) & Neolithic Levantines is that one is "Basal-rich + ANE"  and the other is "Basal-rich + Villabruna":

The first PCA where the triangle is clearly visible is directly based on David's new Basal-rich K=7 ADMIXTURE run but it's data is still in line with what we see in a PCA directly based on autosomal SNPs like the one below:

Here, you can see relatively the same population structure. The more north a population pulls correlates with how much ANE-related ancestry they have, the more east a population pulls correlates with how much "Basal-rich" type ancestry they have and, finally, the more west a population pulls correlates with how much Villabruna-related ancestry they have.

So it seems David's indeed come up with a decent model here. What we really need now is to figure out exactly what "Basal Eurasian" is and to understand some of the earlier pre-history of West Asia to a point where we can grasp how the substantial Ancient North Eurasian-related and Villabruna-related ancestry, found in its Neolithic and Epipaleolithic inhabitants, got there. [note]


1. The genetic structure of the world's first farmers, Lazaridis et al. 2016

2. The Demographic Development of the First Farmers in Anatolia, Kılınç et al.


1. The "Basal-rich" cluster itself is likely to be a mixture between something related to European Hunter-Gatherers like those of the "Villabruna/WHG" cluster and Basal Eurasian ancestry. Even the new Lazaridis pre-print implies as much via this figure when demonstrating what makes up the Natufian samples.

Some new Neolithic Anatolians

Well, thanks to a new study, we now have some new Neolithic Anatolian samples. This time they're from South-Central Anatolia and date to between 8300 and 5800 BCE.

Seems the Boncuklu samples (~8300-7500 BCE) are nearly identical to the Barcın (Northwestern) Neolithic Anatolians in terms of WHG/Villabruna-related ancestry and "ENF-like/Basal-rich"-related ancestry whilst the Tepcek samples (~7500-5800 BCE) are less Villabruna-shifted and thus pull a bit more toward Neolithic Levantines and Natufians. You can see this in David's PCA (Principal Component Analysis based on autosomal SNPs) below:

The more left a population pulls; the greater the affinity for Villabruna-type Hunter-Gatherers whilst the more right the pull indicates how ENF-like/Basal-rich they are. Finally, the more north a population pulls indicates how "ANE" shifted they are. Neolithic Anatolians, Neolithic Levantines and Natufians pull the absolute least toward the north as they seem to lack ANE-related admixture.


1. The Demographic Development of the First Farmers in Anatolia, Kılınç et al.


1. The mtDNA diversity among these samples is rather interesting to me as someone from the Horn of Africa, to be honest. N1a1a1, N1b, K1a, K1a12a, U3: these are quite close to or directly overlap with the mtDNA Haplogroups you can find among Somalis and other Horn African populations.