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Wednesday, September 16, 2020

Domestic horses were introduced into Anatolia and Transcaucasia during the Bronze Age (Guimaraes et al. 2020)


Over at Science Advances at this LINK. This is a very important paper because it basically eliminates West Asia as the source of the modern domestic horse lineage, which leaves the Pontic-Caspian steppe in Eastern Europe as the only viable option.

It also corroborates the linguistic theory that the Proto-Indo-European homeland was located on the Pontic-Caspian steppe. That's because the horse is a key animal in the Proto-Indo-European pantheon, and it appears in Indo-European mythology in intricate roles. This suggests that the speakers of Proto-Indo-European weren't just familiar with the horse but also managed to domesticate it. From the paper:

Abstract: Despite the important roles that horses have played in human history, particularly in the spread of languages and cultures, and correspondingly intensive research on this topic, the origin of domestic horses remains elusive. Several domestication centers have been hypothesized, but most of these have been invalidated through recent paleogenetic studies. Anatolia is a region with an extended history of horse exploitation that has been considered a candidate for the origins of domestic horses but has never been subject to detailed investigation. Our paleogenetic study of pre- and protohistoric horses in Anatolia and the Caucasus, based on a diachronic sample from the early Neolithic to the Iron Age (~8000 to ~1000 BCE) that encompasses the presumed transition from wild to domestic horses (4000 to 3000 BCE), shows the rapid and large-scale introduction of domestic horses at the end of the third millennium BCE. Thus, our results argue strongly against autochthonous independent domestication of horses in Anatolia.
Guimaraes et al., Ancient DNA shows domestic horses were introduced in the southern Caucasus and Anatolia during the Bronze Age, Science Advances 16 Sep 2020: Vol. 6, no. 38, eabb0030, DOI: 10.1126/sciadv.abb0030

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Tuesday, September 8, 2020

Warriors from at least two different populations fought in the Tollense Valley battle


I can't get the genotype data from the Burger et al. paper. The lead authors, Joachim Burger and Daniel Wegmann, aren't replying to my emails.

But they were gracious enough to release the BAM files for each of their samples, and these files can be converted to genotype data. So I've included ten of the Tollense Valley warriors (DEU_Tollense_BA) in the Global25 datasheets (see here).

The claim in the paper that these warriors "represent an unstructured population" is absolutely false and extremely naive.

Below are a couple of Principal Component Analysis (PCA) plots produced with Vahaduo Global25 views. The samples are labeled according to their Y-chromosome haplogroups. To see interactive versions of the same plots, paste the Global25 coordinates from the text file here into the relevant fields here.


These warriors are not a single unstructured population, because they cover too much ground in the above plots for that to be possible. It's clear to me that they represent at least two different groups from Central Europe and surrounds.

Of course, this would be a lot easier to work out if Burger et al. cared to supply more information about each of the warriors, such as their attire, weapons, circumstances of death, and so on. It's a complete mystery to me why this wasn't included in the paper, and the authors are refusing to talk to me, so it's unlikely that I'll ever be able to get it from them.

In the absence of such crucial archeological and anthropological data, I don't want to speculate too much, and get overly creative, but here are a couple of possible scenarios to explain the ancient DNA results:
- this may have been a battle between two Central European armies, one rich in Y-haplogroup R1b and the other rich in Y-haplogroup I2a, as well as their allies or hired help, including warriors from Eastern Europe belonging to Y-haplogroup R1a

- or perhaps it was an invasion from the east by warriors rich in Y-haplogroup R1a, and it was a success, with the local armies, rich in Y-haplogroups R1b and I2a, losing the battle and suffering most of the casualties.

I'm sure that one day someone will attempt to undertake a decent multidisciplinary study of this epic battle, and we'll at least have a rough idea about what happened. Or not.

Citation...

Burger et al., Low Prevalence of Lactase Persistence in Bronze Age Europe Indicates Ongoing Strong Selection over the Last 3,000 Years, Current Biology, Available online 3 September 2020, https://doi.org/10.1016/j.cub.2020.08.033

See also...

Genetic and linguistic structure across space and time in Northern Europe

Sunday, September 6, 2020

Low prevalence of lactase persistence in Bronze Age Europe (Burger et al. 2020)


Over at Current Biology at this LINK. Unfortunately, this is the long-awaited Tollense Valley battle paper. Despite the obvious presence of some very interesting genetic substructures among the Tollense Valley warriors (see here), the authors have the audacity to claim that these individuals represent a "single unstructured Central/Northern European population".

One of the warriors, labeled WEZ56, belongs to Y-haplogroup R1a and shows an exceedingly Balto-Slavic-like genome-wide genetic structure. But none of this is even mentioned in passing in the paper. Indeed, according to Burger at al., WEZ56 is best classified as belonging to R1, even though the R1a classification is quite secure based on the raw data that the authors posted online.

Be extremely wary of what you read in this paper, and anything else that these scientists have published in the past and will publish in the future. Below is the paper summary:

Lactase persistence (LP), the continued expression of lactase into adulthood, is the most strongly selected single gene trait over the last 10,000 years in multiple human populations. It has been posited that the primary allele causing LP among Eurasians, rs4988235-A [1], only rose to appreciable frequencies during the Bronze and Iron Ages [2, 3], long after humans started consuming milk from domesticated animals. This rapid rise has been attributed to an influx of people from the Pontic-Caspian steppe that began around 5,000 years ago [4, 5]. We investigate the spatiotemporal spread of LP through an analysis of 14 warriors from the Tollense Bronze Age battlefield in northern Germany (∼3,200 before present, BP), the oldest large-scale conflict site north of the Alps. Genetic data indicate that these individuals represent a single unstructured Central/Northern European population. We complemented these data with genotypes of 18 individuals from the Bronze Age site Mokrin in Serbia (∼4,100 to ∼3,700 BP) and 37 individuals from Eastern Europe and the Pontic-Caspian Steppe region, predating both Bronze Age sites (∼5,980 to ∼3,980 BP). We infer low LP in all three regions, i.e., in northern Germany and South-eastern and Eastern Europe, suggesting that the surge of rs4988235 in Central and Northern Europe was unlikely caused by Steppe expansions. We estimate a selection coefficient of 0.06 and conclude that the selection was ongoing in various parts of Europe over the last 3,000 years.

Burger et al., Low Prevalence of Lactase Persistence in Bronze Age Europe Indicates Ongoing Strong Selection over the Last 3,000 Years, Current Biology, Available online 3 September 2020, https://doi.org/10.1016/j.cub.2020.08.033

See also...

Warriors from at least two different populations fought in the Tollense Valley battle