Shared maternal ancestry between Slavs and Germanics probably dates to the Metal Ages

Over at the Russian Journal of Genetics behind a paywall at this LINK. Emphasis is mine:

Abstract: The structure and diversity of mitochondrial DNA (mtDNA) macrohaplogroup U lineages in Russians from Eastern Europe are studied on the basis of analysis of variation of nucleotide sequences of complete mitochondrial genomes. In total, 132 mitochondrial genomes belonging to haplogroups U1, U2e, U3, U4, U5, U7, U8a, and K are characterized. Results of phylogeographic analysis show that the mitochondrial gene pool of Russians contains mtDNA haplotypes belonging to subhaplogroups that are characteristic only of Russians and other Eastern Slavs (13.7%), Slavs in general (11.4%), Slavs and Germans (17.4%), and Slavs, Germans, and Baltic Finns (9.8%). Results of molecular dating show that ages of mtDNA subhaplogroups to which Russian mtDNA haplotypes belong vary in a wide range, from 600 to 17000 years. However, molecular dating results for Slavic and Slavic-Germanic mtDNA subhaplogroups demonstrate that their formation mainly occurred in the Bronze and Iron Ages (1000–5000 years ago). Only some instances (for subhaplogroups U5b1a1 and U5b1e1a) are characterized by a good agreement between molecular dating results and the chronology of Slavic ethnic history based on historical and archaeological data.

Malyarchuk, B.A., Derenko, M.V. & Litvinov, The macrohaplogroup U structure in Russians, A.N. Russ J Genet (2017) 53: 498. doi:10.1134/S1022795417020053

Globular Amphora people were starkly different from Yamnaya people

The figure below is from the recent Mathieson et al. 2017 preprint; slightly edited to highlight the results of nine Globular Amphora Culture (GAC) samples from two burial sites in what are now Poland and Ukraine.

Despite living in East Central Europe at about the same time as the nearby Yamnaya people of the Pontic-Caspian Steppe, these GAC individuals show practically zero Yamnaya-related or steppe ancestry (note the almost total absence of the orange "Yamnaya" component in the Globular_Amphora results in the ADMIXTURE bar graph). Instead, they're very similar to Chalcolithic and Middle Neolithic Central and Western Europeans, with whom they overlap in the Principal Component Analysis (PCA).

During the tail end of the GAC period, East Central Europe was suddenly dominated by a new archaeological complex called the Corded Ware Culture (CWC). Although most CWC individuals sampled to date show minor GAC-related ancestry, they're overwhelmingly Yamnaya-like, which suggests that by and large the CWC population has its origins on the Pontic-Caspian Steppe. In fact, some of the earliest CWC examples from the Baltic States, such as Latvia_LN in the ADMIXTURE bar graph, are basically identical to Yamnaya people.

It was suggested not long ago that the presence of Yamnaya-related ancestry in modern-day Europeans could be mostly explained by the so called Isolation-by-Distance phenomenon (see here). But as I said at the time, this was a major faux pas, and thanks to these GAC samples I now have direct evidence from ancient DNA to back me up. So forget the idea of anything resembling a gentle cline in Yamnaya-like ancestry east to west across Europe before proto-CWC and Yamnaya exploded from the steppes.

By the way, in that critique I said that it's not possible to recapitulate ancient populations with ADMIXTURE components. I stand by that statement, although as we can see in Mathieson et al. 2017, it is possible to get close at times with enough of the right ancient samples; close enough to make some general observations anyway.

Interestingly, on the PCA plot, the European Bronze Age cluster is more or less half way between GAC and Latvia_LN. This is also where modern-day Poles and Ukrainians cluster on such plots when they're not significantly skewed by projection bias or shrinkage. Thus, I do wonder if the Slavs of East Central Europe are essentially a 50/50 mixture of early CWC and late GAC? I'll try and test this when the Mathieson et al. 2017 dataset goes online.

Reference...

Mathieson et al., The Genomic History Of Southeastern Europe, bioRxiv, Posted May 9, 2017, doi: https://doi.org/10.1101/135616

See also...

Late PIE ground zero now obvious; location of PIE homeland still uncertain, but...