Friday, June 26, 2015
I may have discovered an interesting pattern in the Allentoft et al. data. It seems that during the Late Neolithic/Bronze Age, Scandinavia was populated by two somewhat different populations; one characterized by Y-Chromosome haplogroup R1b and a genome-wide genetic structure typical of present-day Northwestern Europeans, and another by Y-Chromosome haplogroup R1a and a relatively more eastern genome-wide genetic profile.
Below are two Principal Component Analyses (PCA), both featuring ancient Swedish genomes classified as part of the Late Neolithic Battle-Axe archeological culture. However, the first sample clusters near present-day Norwegians and belongs to Y-haplogroup R1b-U106, which is nowadays typically known as a Germanic paternal marker. On the other hand, the second sample clusters among present-day Russians and Mordovians, from all the way near the Volga, and belongs to Y-haplogroup R1a-Z645, which very likely expanded from Eastern Europe during the Late Neolithic.
Here's another example of basically the same thing, but this time with two ancient genomes from Denmark. If you're having trouble finding the ancient samples, download the PDF files and type their IDs in the PDF search field.
Coincidence? Probably not, but we obviously need more samples to confirm these results and establish that there is indeed a pattern.
Allentoft et al., Bronze Age population dynamics, selection, and the formation of Eurasian genetic structure, Nature 522, 167–172 (11 June 2015) doi:10.1038/nature14507
Monday, June 22, 2015
Felix at GGT is in the process of uploading the genomes from the recent Pinhasi et al. paper. The file for the early Neolithic sample from Barcin, Turkey, is basically ready. I analyzed it with my K8 model and got these results (click on the image to enlarge).
I was only able to use a couple hundred SNPs for the test, so the outcome can't be taken too seriously. But it does make sense. The lack of Ancient North Eurasian (ANE) ancestry isn't surprising, because it mirrors the results of early European farmers we've seen to date.
Moreover, the relatively high level of Western European Hunter-Gatherer (WHG) ancestry, or at least something very similar, is also in line with expectations, considering that the sample was dug up in far western Anatolia, almost on the European border.
I also ran an Identical-by-State (IBS) affinity test using the Human Origins dataset and around 1800 SNPs. The results broadly back up the K8 analysis, with southern Europeans topping the list.
Pinhasi R, Fernandes D, Sirak K, Novak M, Connell S, Alpaslan-Roodenberg S, et al. (2015) Optimal Ancient DNA Yields from the Inner Ear Part of the Human Petrous Bone. PLoS ONE 10(6): e0129102. doi:10.1371/journal.pone.0129102
The Near East ain't what it used to be
Wednesday, June 10, 2015
It'll take me a while to digest all of the information in this massive new Allentoft et al. paper. But I've already noticed that, just like in Haak et al. 2015, the Yamnaya samples are again from the eastern half of the Yamnaya horizon. This time, however, not all of the Yamnaya individuals carry Y-haplogroup R1b; one of the five samples belongs to Y-haplogroup I2a (see here).
So I'm wondering what more westerly Yamnaya sites will reveal in the future, considering the predominance of Y-haplogroup R1a among the Corded Ware individuals sampled to date, and the close genome-wide relationship between the Yamnaya and Corded Ware?
Abstract: The Bronze Age of Eurasia (around 3000–1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.
Allentoft et al., Population genomics of Bronze Age Eurasia, Nature 522, 167–172 (11 June 2015) doi:10.1038/nature14507
R1a-M417 from Eneolithic Ukraine!!!11