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Wednesday, October 20, 2021

Modern domestic horses came from the Eastern European steppe

Over at Nature at this LINK. I'm getting the impression that geneticists and the editors at Nature are really crap at geography. Obviously, this paper argues that modern domestic horses came from the Pontic-Caspian steppe, which is located very firmly in Eastern Europe. But, inexplicably, instead of actually saying this, the authors came up with the much more ambiguous term Western Eurasian steppes, and even put that in the title. I wonder why? Here's the paper abstract:

Domestication of horses fundamentally transformed long-range mobility and warfare 1. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling 2,3,4 at Botai, Central Asia around 3500 bc3. Other longstanding candidate regions for horse domestication, such as Iberia 5 and Anatolia 6, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes [my note: they actually mean the Pontic-Caspian steppe, which is located in Eastern Europe], especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 bc, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association 7 between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe [my note: the Yamnaya culture was located in Europe] around 3000 bc 8,9 driving the spread of Indo-European languages 10. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium bc Sintashta culture 11,12.

Librado, P., Khan, N., Fages, A. et al. The origins and spread of domestic horses from the Western Eurasian steppes. Nature (2021).

Update: I emailed one of the lead authors, Ludovic Orlando, asking him for a comment. Here it is:

Thanks for your interest in our research. We indeed struggled finding the term that would be most appropriate and this was discussed with our coauthors. The Pontic-Caspian steppe would seem the most obvious choice but my understanding is that this would include a large region, stretching from the most north-western side of the Black sea to the foothills of the Urals. This is larger than the signature recovered in our data. My understanding is that the Eastern European steppes would also stretch more northernly than the region that we narrowed down. Eastern European steppes was also not immediately clear, even for European scholars such as myself. Therefore, it did not seem that there were any terms that were ready-made for truly qualifying our findings. We thus went for Western Eurasian steppes in the main title, and sticked to more precise locations such as the Don-Volga region in the main text. I guess that this is one of those cases where the activities of past herders did not exactly follow some geographic terms that would only be defined thousands of years later.

However, the Pontic-Caspian steppe and the Eastern European steppe are in fact terms that describe the western end of the Eurasian steppe. So they should be totally interchangeable with the term Western Eurasian steppes. Except, at least to me, they seem less ambiguous.

Ergo, the Eastern European steppe can't be more northerly than the Western Eurasian steppes, because it's the same thing. Moreover, the Pontic-Caspian steppe can't stretch further west than the Western Eurasian steppes, because, again, it's the same thing.

Indeed, the land north of the Eastern European/Western Eurasian steppes is called the forest steppe.

See also...

Friday, October 15, 2021

Coming soon?

This ISBA9 abstract seems to be highly relevant to the ultimate origins of the Yamnaya and Corded Ware peoples. Emphasis is mine:

Genomic signals of continuity and admixture in the Caucasus

Ghalichi Ayshin et al.

Situated between the Black and Caspian Sea, the Caucasus is a key geographic region that connects the Near East and the Eurasian Steppe, with a great ecological diversity of ecotones and landscapes rich in natural resources. A recent archaeogenetic study has shown that the genetically diverse Eneolithic and Bronze Age groups of the steppe and mountains correspond to eco-geographic zones in the Caucasus. However, the formation, interactions and population dynamics warrant further investigation. In this study we explore new genome-wide data of 68 individuals from 20 archaeological cultures across the Caucasus mountains, the piedmont and the steppe extending our temporal transect to 6000 years, doubling the number of available genomes from the region. We present the first genomic data from a Mesolithic individual (6100 calBCE) from the Northwest Caucasus that shows Eastern hunter-gatherer ancestry, Neolithic individuals from Georgia, as well as new data from genetically unexplored regions/cultures in the northeastern highlands and the dry steppe. We observe a degree of genetic continuity through time within the main mountain and steppe genetic groups, but also identify various episodes of gene flow between these and the neighboring regions. In the Late Eneolithic period, we find evidence of admixture from the south into the steppe groups, detectable through the presence of Anatolian_Neolithic-like ancestry. During the Bronze Age, we found in Steppe Maykop individuals a genetic link to West Siberian hunter-gatherers, a component that is absent from Yamnaya, North Caucasus and Catacomb groups, but reappears in Bronze Age individuals associated with the Lola culture.

I'm not quite sure what it's saying though. Is the Mesolithc individual from the Northwest Caucasus actually an Eastern European hunter-gatherer, or, as I'm expecting, a mixture between Caucasus and Eastern European hunter-gatherers? If the latter, then it's game over for the Out-of-Iran and Out-of-Armenia Indo-European hypotheses that have been so popular among academics in recent years.

The authors also mention the spread of Anatolian-related ancestry into the Eastern European steppe during the Late Eneolithic. They're probably referring to the phenomenon that gave rise to the so called Steppe Maykop outliers. The ISBA9 abstract PDF book is freely available here.

See also...

Understanding the Eneolithic steppe

Ancient DNA vs Ex Oriente Lux

A note on Steppe Maykop

Monday, September 27, 2021

The genetic origin and legacy of the Etruscans (Posth et al. 2021)

Over at Science Advances at ths LINK. I'll take a closer look at this issue after I get the relevant genotype data. Anyone got the link? Here's the paper abstract:

The origin, development, and legacy of the enigmatic Etruscan civilization from the central region of the Italian peninsula known as Etruria have been debated for centuries. Here we report a genomic time transect of 82 individuals spanning almost two millennia (800 BCE to 1000 CE) across Etruria and southern Italy. During the Iron Age, we detect a component of Indo-European–associated steppe ancestry and the lack of recent Anatolian-related admixture among the putative non–Indo-European–speaking Etruscans. Despite comprising diverse individuals of central European, northern African, and Near Eastern ancestry, the local gene pool is largely maintained across the first millennium BCE. This drastically changes during the Roman Imperial period where we report an abrupt population-wide shift to ~50% admixture with eastern Mediterranean ancestry. Last, we identify northern European components appearing in central Italy during the Early Middle Ages, which thus formed the genetic landscape of present-day Italian populations.

Citation: C. Posth, V. Zaro, M. A. Spyrou, S. Vai, G. A. Gnecchi-Ruscone, A. Modi, A. Peltzer, A. Mötsch, K. Nägele, &. J. Vågene, E. A. Nelson, R. Radzevičiūtė, C. Freund, L. M. Bondioli, L. Cappuccini, H. Frenzel, E. Pacciani, F. Boschin, G. Capecchi, I. Martini, A. Moroni, S. Ricci, A. Sperduti, M. A. Turchetti, A. Riga, M. Zavattaro, A. Zifferero, H. O. Heyne, E. Fernández-Domínguez, G. J. Kroonen, M. McCormick, W. Haak, M. Lari, G. Barbujani, L. Bondioli, K. I. Bos, D. Caramelli, J. Krause, The origin and legacy of the Etruscans through a 2000-year archeogenomic time transect. Sci. Adv. 7, eabi7673 (2021).

See also...

Etruscans, Latins, Romans and others

Friday, September 17, 2021

Lizard Gorge

I was hiking through one of my favorite wilderness areas the other day. I call this place Lizard Gorge because it's full of monitor lizards that strut around like they own it.

Just a few minutes into my hike I noticed some birds going crazy atop a massive, hollow tree. They were calling loudly as if a predator was near, and, sure enough, when I peered into this tree I saw two monitors tearing apart the carcass of a large animal.

It was a gory but fascinating sight. Unfortunately, the stench made it difficult to bear, so I decided to move on.

As I backed away I was attacked by a swarm of insects. Initially, in my panic, I thought they were spiders, but on closer inspection they turned out to be gigantic ants.

I was bitten on the hand, arm and neck. It hurt like hell. The bite on the neck was especially painful. Were these ants venomous? Was I at risk of a dangerous allergic reaction? I didn't know, so I ran, seemingly for my life.

After a few minutes, however, the pain went away. I sat down beside a creek, looked all around for ants, and had a cool drink (from my hydration pack, not the creek). Despite my ordeal, it was an awesome hike, and I managed to get some great pics. Enjoy!

See also...

Eagle country

Wednesday, September 15, 2021

Yamnaya people drank horse milk (Wilkin et al. 2021)

Over at Nature at this LINK. I'm guessing the claim that Yamnaya pastoralists lived in Scandinavia is a huge typo. Obviously, the authors are referring to the people of the Corded Ware culture (CWC). From the paper:

During the Early Bronze Age, populations of the western Eurasian steppe expanded across an immense area of northern Eurasia. Combined archaeological and genetic evidence supports widespread Early Bronze Age population movements out of the Pontic–Caspian steppe that resulted in gene flow across vast distances, linking populations of Yamnaya pastoralists in Scandinavia with pastoral populations (known as the Afanasievo) far to the east in the Altai Mountains1,2 and Mongolia3. Although some models hold that this expansion was the outcome of a newly mobile pastoral economy characterized by horse traction, bulk wagon transport4,5,6 and regular dietary dependence on meat and milk5, hard evidence for these economic features has not been found. Here we draw on proteomic analysis of dental calculus from individuals from the western Eurasian steppe to demonstrate a major transition in dairying at the start of the Bronze Age. The rapid onset of ubiquitous dairying at a point in time when steppe populations are known to have begun dispersing offers critical insight into a key catalyst of steppe mobility. The identification of horse milk proteins also indicates horse domestication by the Early Bronze Age, which provides support for its role in steppe dispersals. Our results point to a potential epicentre for horse domestication in the Pontic–Caspian steppe by the third millennium bc, and offer strong support for the notion that the novel exploitation of secondary animal products was a key driver of the expansions of Eurasian steppe pastoralists by the Early Bronze Age.

Wilkin, S., Ventresca Miller, A., Fernandes, R. et al. Dairying enabled Early Bronze Age Yamnaya steppe expansions. Nature (2021).

See also...

On the origin of the Corded Ware people

Saturday, September 4, 2021

The genomic formation of modern Balkan peoples (Olalde et al. 2021 preprint)

Over at bioRxiv at this LINK. This preprint deals with some very complex issues, so I can't say much about it until I have a good look at the relevant genotype data. However, for now, my impression is that the authors have oversimplified the genetic origins of most Balkan peoples.

For instance, they model the present-day Greek population as a two way mixture between ancient Greeks from a Greek colony in Iberia and present-day Mordovians. The Mordovians are basically a proxy for the Slavs who moved into the Balkans during the Medieval period.

However, the problem is that, strictly speaking, this isn't a historically plausible model, because Mordovians are actually a Uralic-speaking group from the Volga region with significant Siberian ancestry. Needless to say, it's extremely unlikely that anyone like them had an appreciable impact on the present-day Greek gene pool.

So instead I'd like to see the authors try three-way and four-way models with ancients from Mycenae, Anatolia and some places (well to the west of the Volga River) likely to have been inhabited by early Slavs.

Feel free to let me know what you think about this preprint in the comments below. Here's the abstract:

The Roman Empire expanded through the Mediterranean shores and brought human mobility and cosmopolitanism across this inland sea to an unprecedented scale. However, if this was also common at the Empire frontiers remains undetermined. The Balkans and Danube River were of strategic importance for the Romans acting as an East-West connection and as a defense line against “barbarian” tribes. We generated genome-wide data from 70 ancient individuals from present-day Serbia dated to the first millennium CE; including Viminacium, capital of Moesia Superior province. Our analyses reveal large scale-movements from Anatolia during Imperial rule, similar to the pattern observed in Rome, and cases of individual mobility from as far as East Africa. Between ∼250-500 CE, we detect gene-flow from Central/Northern Europe harboring admixtures of Iron Age steppe groups. Tenth-century CE individuals harbored North-Eastern European-related ancestry likely associated to Slavic-speakers, which contributed >20% of the ancestry of today’s Balkan people.

Olalde et al., Cosmopolitanism at the Roman Danubian Frontier, Slavic Migrations, and the Genomic Formation of Modern Balkan Peoples, bioRxiv, posted August 31, 2021, doi:

See also...

A Greek tragedy

Friday, August 27, 2021

R1a vs R1b in third millennium BCE central Europe (Papac et al. 2021)

R1a-M417 and R1b-L51 are by far the most important Y-chromosome haplogroups in Europe today. More precisely, R1a-M417 dominates in Eastern Europe, while R1b-L51 in Western Europe.

It's been obvious for a while now, at least to me, that both of these Y-haplogroups are closely associated with the men of the Late Neolithic Corded Ware culture (CWC). Indeed, in my mind they're the main genetic signals of its massive expansion, probably from a homeland somewhere north of the Black Sea in what is now Ukraine.

I'm still not exactly sure how the east/west dichotomy between R1a and R1b emerged in Europe, but, thanks to a new paper by Papac et al. at Science Advances, at least now I have a working hypothesis about that. Below is a quote from the said paper, emphasis is mine:

In addition to autosomal genetic changes through time, we observe a sharp reduction in Y-chromosomal diversity going from five different lineages in early CW to a dominant (single) lineage in late CW (Fig. 4A). We used forward simulations to explore the demographic scenarios that could account for the observed reduction in Y-chromosomal diversity. Performing 1 million simulations of a population with a starting frequency of R1a-M417(xZ645) centered around the observed starting frequency in Bohemia_CW_Early (3 of 11, 0.27), we assessed the plausibility of this lineage reaching the observed frequency in Bohemia_CW_Late (10 of 11, 0.91) in the time frame of 500 years under a model of a closed population and random mating (Materials and Methods). We reject the “neutral” hypothesis, i.e., that this change in frequency occurred by chance, given a wide range of plausible population sizes. Instead, our results suggest that R1a-M417(xZ645) was subject to a nonrandom increase in frequency, resulting in these males having 15.79% (4.12 to 44.42%) more surviving offspring per generation relative to males of other Y-haplogroups. We also find that this change in Y chromosome frequency is extreme compared to the changes in allele frequencies at fully covered autosomal 1240k sites within the same males, suggesting a process that disproportionately affected Y-chromosomal compared to autosomal genetic diversity, ruling out a population bottleneck as the likely cause. Our results suggest that the Y-lineage diversity in early CW males was supplanted by a nonrandom process [selection, social structure, or influx of nonlocal R1a-M417(xZ645) lineages] that drove the collapse in Y-chromosomal diversity. A simultaneous decline of Y-chromosomal diversity dating to the Neolithic has been observed across most extant Y-haplogroups (64), possibly due to increased conflict between male-mediated patrilines (65). We view that changes in social structure (e.g., an isolated mating network with strictly exclusive social norms) could be an alternative cause but would be difficult to distinguish in the underlying model parameters.

Right, so even though the CWC was clearly a community of closely related groups, there must have been some competition between its different clans. And since these clans were highly patriarchal and patrilineal, this competition probably led to different paternal lineages dominating different parts of the CWC horizon, with M417 becoming especially common in the east and L51 in the west.

Of course, the expansions of post-Corded Ware groups, such as the M417-rich Slavs in Eastern Europe and L51-rich Celts in Western Europe, were also instrumental in creating Europe's R1a/R1b dichotomy, but obviously these groups were in large part the heirs of the CWC.

By the way, most of the samples from Papac et al. are already in the Global25 datasheets linked here. Look for the labels listed here. Below is a plot made from the Global25 data courtesy of regular commentator Matt.
Citation: L. Papac, M. Ernée, M. Dobeš, M. Langová, A. B. Rohrlach, F. Aron, G. U. Neumann, M. A. Spyrou, N. Rohland, P. Velemínský, M. Kuna, H. Brzobohatá, B. Culleton, D. Daněček, A. Danielisová, M. Dobisíková, J. Hložek, D. J. Kennett, J. Klementová, M. Kostka, P. Krištuf, M. Kuchařík, J. K. Hlavová, P. Limburský, D. Malyková, L. Mattiello, M. Pecinovská, K. Petriščáková, E. Průchová, P. Stránská, L. Smejtek, J. Špaček, R. Šumberová, O. Švejcar, M. Trefný, M. Vávra, J. Kolář, V. Heyd, J. Krause, R. Pinhasi, D. Reich, S. Schiffels, W. Haak, Dynamic changes in genomic and social structures in third millennium BCE central Europe. Sci. Adv. 7, eabi6941 (2021).

See also...

On the origin of the Corded Ware people

Understanding the Eneolithic steppe

Conan the Barbarian probably belonged to Y-haplogroup R1a

Tuesday, July 20, 2021

On the origin of the Corded Ware people

There's been a lot of talk lately about the finding that the peoples associated with the Corded Ware and Yamnaya archeological cultures were close cousins (for instance, see here). As I've already pointed out, this is an interesting discovery, but, at this stage, it's difficult to know what it means exactly.

It might mean that the Yamnayans were the direct predecessors of the Corded Ware people. Or it might just mean that, at some point, the Corded Ware and Yamnaya populations swapped women regularly (that is, they practiced female exogamy with each other).

In any case, I feel that several important facts aren't being taken into account by most of the interested parties. These facts include, in no particular order:

- despite being closely related, the Corded Ware and Yamnaya peoples were highly adapted to very different ecological zones - temperate forests and arid steppes, respectively - and this is surely not something that happened within a few years and probably not even within a couple of generations

- both the Corded Ware and Yamnaya populations expanded widely and rapidly at around the same time, but never got in each others way, probably because they occupied very different ecological niches

- despite sharing the R1b Y-chromosome haplogroup, their paternal origins were quite different, with Corded Ware males rich in R1a-M417 and R1b-L51 and Yamnaya males rich in R1b-Z2103 and I2a-L699

I suppose it's possible that the Corded Ware people were overwhelmingly and directly derived from the Yamnaya population. But right now my view is that, even if they were, then the Yamnaya population that they came from was quite different from the classic, R1b-Z2103-rich Yamnaya that spread rapidly across the steppes.

Indeed, perhaps what we're dealing with here is a very early (proto?) Yamnaya gene pool located somewhere in the border zone between the forests and the steppes, that then split into two main sub-populations, with one of these groups heading north and the other south?

I do wonder what David Anthony would say if he was made aware of the above mentioned facts? Then again, perhaps he's already aware of them, and simply chose to ignore them when formulating his latest theory about the origin of the Corded Ware people?

See also...

Monday, June 28, 2021

The PIE homeland controversy: June 2021 status report

Archeologist David Anthony has made several appearances online recently to promote his theories about the origins of the Corded Ware and Yamnaya cultures and peoples.

In a clip on Youtube he reiterated his theory that the so called Iranian-related ancestry in the Yamnaya people actually came from what is now Iran, and, more precisely, that it was carried by hunter-gatherers who travelled relatively rapidly from the South Caspian region into the Volga Delta in what is now Russia.

It's still a complete mystery to me as to why a group of hunter-gatherers from the South Caspian would undertake such a migration, instead of, say, expanding their range gradually over thousands of years, first into the Caucasus and eventually into Eastern Europe.

But there's a more serious problem with Anthony's theory: it contradicts the currently available ancient DNA. That's because the so called Iranian-related ancestry in the Yamnaya people is most closely related to the Kotias and Satsurblia hunter-gatherers from what is now Georgia, and these hunter-gatherers form a separate clade from the earliest samples from what is now Iran. For instance, see here and here.

Also, in a podcast on Razib's blog, Anthony doubled down on his theory that Y-chromosome haplogroup R1a was closely associated with Yamnaya plebs who were excluded from Kurgan burials, and, as a result, their remains haven't yet been sampled.

At least this theory isn't yet contradicted by ancient DNA, but it's more complicated and less parsimonious than my theory, which posits that R1a, or rather R1a-M417, was simply a very rare lineage in the Yamnaya population, and that it only became a common and widespread marker thanks to the Corded Ware expansion (see here).

Intriguingly, my understanding is that there are several unpublished R1a samples from the Caspian and Volga steppes at Harvard's David Reich Lab that have been classified by its scientists as Yamnaya outliers. Of course, Anthony is collaborating on at least one major paper with this lab (see here).

Ergo, I strongly suspect that Anthony's theory is in part based on these Yamnaya outliers. However, I also believe that these samples are wrongly dated and probably represent Scythians and/or Sarmatians. I'll be able to look into that if they're ever published.

Speaking of the David Reich Lab, its leading scientists, David Reich and Nick Patterson, have also made appearances online recently, on Youtube and Razib's blog, respectively, to reveal that the Corded Ware and Yamnaya peoples aren't just very similar genetically, but in fact close cousins.

This is a very interesting finding. Apparently it's based on a relatively high level of Identity-by-Descent (IBD) segment sharing between Corded Ware and Yamnaya samples, but that's all I know. I'm guessing that the relevant paper is coming soon (that is, within the next five years).

However, the long-standing question that the readers of this blog want to see answered is not whether the Corded Ware and Yamnaya peoples are close cousins, but whether Yamnaya migrants founded the Corded Ware culture. The obvious way to prove that they did is to find at least one ancient population unambiguously classified as part of the Yamnaya horizon that is rich in the typically Corded Ware Y-haplogroups R1a-M417 and R1b-L151.

See also...

On the origin of the Corded Ware people

The PIE homeland controversy: January 2019 status report

The PIE homeland controversy: August 2019 status report

Thursday, June 17, 2021

Balto-Slavic drift

A few years ago I began using the term "Balto-Slavic genetic drift" to describe the fine-scale genetic signal that is shared by the speakers of Baltic and Slavic languages to the exclusion of Europeans without significant Balto-Slavic ancestry.

As a result, nowadays, many people online use the term "Balto-Slavic drift" when referring to this phenomenon.

The easiest way to prove that Balto-Slavic drift exists is to run a fine-scale Principal Component Analysis (PCA) of European genetic variation with a lot of Balto-Slavic samples in the mix. Indeed, my Global25 PCA analysis does a great job of illustrating the impact of Balto-Slavic drift on the population structure of Europe both in PCA plots and mixture models (for instance, see here).

It's also possible to tease out Balto-Slavic drift with formal statistics. I showed this indirectly in a recent blog post about Greek population structure (see here). In this post I'm going to demonstrate how to explicitly and formally test for Balto-Slavic drift both in ancient and present-day samples.

To do this we need to find stats that basically split Baltic and Slavic speakers from other Europeans, such as f4(Outgroup,Test;Bell_Beaker_NDL,Baltic_LVA_BA). In this f4-stat, Baltic_LVA_BA is the ancient reference population with an unusually high level of Balto-Slavic drift, while Bell_Beaker_NDL is a fairly similar population overall in terms of ancient ancestry components, but with practically zero Balto-Slavic drift.

Note that the statistics with the most significant Z scores (>3) involve populations that speak Baltic or Slavic languages, or their neighbors who plausibly harbor significant Baltic and/or Slavic ancestry. Among the ancient, mostly Scandinavian, populations (from Margaryan et al. 2020 and marked with the VK2020 prefix), significant Balto-Slavic drift only appears in the more easterly and/or later groups from the Viking Age (VA).

Unfortunately, one of the problems with this analysis is that Baltic_LVA_BA and Bell_Beaker_NDL aren't identical in terms of their ancient ancestry proportions. For one, the latter has significantly more Neolithic farmer ancestry. No wonder then, that Greeks, who are mostly of early farmer stock, don't show a significant Z score, despite probably packing a significant amount of Balto-Slavic ancestry dating to the Middle Ages.

In the near future, as more ancient samples become available, it might be possible to find better reference populations for the job and create more accurate, finer-scaled tests.

See also...

Uralian genes

That old chestnut: Northeast vs Northwest Euros