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]


References:

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.

Notes:

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.

References

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

Notes:

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.