East Bell Beakers, an in situ admixture of Yamna settlers and GAC-like groups in Hungary

I wanted to repeat what I said last week in two different posts (see on the new Caucasus and Yamna Hungary samples, and on local groups in contact with Yamna settlers).

We already knew that expanding East Bell Beakers had received influence from a population similar to the available Globular Amphorae culture samples.

  1. Without Yamna settlers, but with Yamna Ukraine and East Bell Beaker samples, including an admixed Yamna Bulgaria sample (from Olalde & Mathieson 2017, and then with their Nature 2018 papers), the most likely interpretation was that Yamna settlers had received GAC ancestry probably during their migration through the Balkans, before turning into East Bell Beakers. However, some comments still supported that it was Corded Ware migrants the ones behind the formation of East Bell Beakers. I couldn’t understand it.
  2. Now we have (with Wang et al. 2018) Yamna settlers (identical to other Yamna groups and Afanasevo migrants) and GAC-like peoples coexisting with them in Hungary, with a Late Chalcolithic Yamna sample from Hungary showing a greater contribution from GAC. However, I still read discussions on Yamna settlers receiving GAC admixture from Corded Ware in Eastern Europe, from GAC in the Dnieper-Dniester area, in Budzhak/Usatovo, etc. I can’t understand this, either.
  3. I will post here the data we have, with the simplest maps and images showing the simplest possible model. No more long paragraphs.

    NOTE. All this data does not mean that this model is certain, especially because we don’t have direct access to the samples. But it is the simplest and most likely one. Sometimes 2+2=4. Even if it turns out later to be false.

    EDIT (30 MAY 2018): In fact, as I commented in the first post about these samples, there is a Yamna LCA/EBA sample probably from Late Yamna (in the North Pontic steppe, west of the Catacomb culture), which shows GAC-like contribution. However, this admixture is lesser than that of Hungary LCA/EBA1 sample, and both Yamna groups (Hungary and steppe) were probably already more sedentary, which also supports different contributions from nearby local GAC-like groups to each region, rather than maintained long-range internal genetic contributions from a single source near the steppe…

    Yamna migrants ca. 3300-2600. Most likely site of admixture with GAC circled in red.
    Yamna – Bell Beaker migration according to Heyd (2007, 2012). Most likely site of admixture with GAC is marked by the evolution of Blue to Red color.
    PCA results. Samples from Yamna Hungary are surrounded by red circles, GAC-like Hungarian groups surrounded by light brown (see below for ADMIXTURE data) Notice the most likely Yamna Hungary sample with GAC admixture clustering closely to CWC Esperstedt outlier, and thus to some East Bell Beaker samples. (d) shows these projected onto a PCA of 84 modern-day West Eurasian populations (open symbols).
    Modified image, with red rectangles surrounding (unreleased) Hungarian samples from Yamna and GAC-like groups. (c) ADMIXTURE results of relevant prehistoric individuals mentioned in the text (filled symbols)
    Modified image, with red rectangles surrounding (unreleased) Yamna samples Notice greater GAC contribution to late Yamna Hungary sample. Modelling results for the Steppe and Caucasus cluster. Admixture proportions based on (temporally and geographically) distal and proximal models, showing additional Anatolian farmer-related ancestry in Steppe groups as well as additional gene flow from the south in some of the Steppe groups as well as the Caucasus groups
    Modified table from Wang et al. (2018) Supplementary materials (in bold, Yamna and related samples; in red, newly reported samples). Notice greater GAC contribution to late Yamna Hungary sample. “Supplementary Table 18. P values of rank=1 and admixture coefficients of modelling the Steppe ancestry populations as a two-way admixture of the Eneolithic_steppe and Globular_Amphora using 14 outgroups. Left populations: Steppe cluster, Eneolithic_steppe, Globular Amphora Right populations: Mbuti.DG, Ust_Ishim.DG, Kostenki14, MA1, Han.DG, Papuan.DG, Onge.DG, Villabruna, Vestonice16, ElMiron, Ethiopia_4500BP.SG, Karitiana.DG, Natufian, Iran_Ganj_Dareh_Neolithic.”

    The CWC outlier from Esperstedt

    I already said that my initial interpretation of the Esperstedt outlier, dated ca. 2430 BC, as due to a late contribution directly from the steppe (i.e. from long-range contacts between late Corded Ware groups from Europe and late groups from the steppe) was probably wrong, seeing how (in Olalde et al. 2017) early East Bell Beaker samples from Hungary and Central Europe clustered closely to this individual.

    Now we see that fully ‘Yamnaya-like’ Yamna settlers lived in Hungary probably for two or three centuries ca. 2900-2600 BC, and the absorption of known (or unknown) Yamna vanguard groups found up to Saxony-Anhalt before 2600 BC would be enough to justify the genomic findings of this individual.

    An outlier it is, then. But probably from admixture with nearby Yamna-like people.

    Image modified by me, from Olalde et al. (2017). PCA of 999 Eurasian individuals. Marked is the Espersted Outlier.