From the paper:
From around 2800 BC, the LNE Bell Beaker culture emerged from the Iberian Peninsula to form one of the first pan-European archaeological complexes. This cultural phenomenon is recognised by a distinctive package of rich grave goods including the eponymous bell-shaped ceramic beakers. The genetic affinities between Central Europe’s Bell Beakers and present-day Iberian populations (Fig. 2) is striking and throws fresh light on long-disputed archaeological models3. We suggest these data indicate a considerable genetic influx from the West during the LNE. These far-Western genetic affinities of Mittelelbe-Saale’s Bell Beaker folk may also have intriguing linguistic implications, as the archaeologically-identified eastward movement of the Bell Beaker culture has recently been linked to the initial spread of the Celtic language family across Western Europe39. This hypothesis suggests that early members of the Celtic language family (for example, Tartessian)40 initially developed from Indo-European precursors in Iberia and subsequently spread throughout the Atlantic Zone; before a period of rapid mobility, reflected by the Beaker phenomenon, carried Celtic languages across much of Western Europe. This idea not only challenges traditional views of a linguistic spread of Celtic westwards from Central Europe during the Iron Age, but also implies that Indo-European languages arrived in Western Europe substantially earlier, presumably with the arrival of farming from the Near East41.It does seem increasingly likely that there was a major Out-of-Iberia episode which may very well have involved a population of relative newcomers (R1b males, undetected in Europe in the pre-5ka period) interacting with an "Iberian" matrilineal substratum and then exporting both R1b and the "Iberian" type of H into most of Western Europe with the Bell Beaker phenomenon. It's hard to think of the Bell Beakers as ultimately descended from the first farmers alone, both because of their distinctive physical type, and also because of the aforementioned absence of R1b in early farmers. More ancient DNA work will certainly help solve many of the remaining puzzles.
Also from the paper:
The demographic reconstruction, which is based on direct calibration points, has major implications for understanding post-glacial human history in Europe. Our new estimate is incompatible with traditional views that the majority of present-day hg H lineages were carried into Central, Northern and Eastern Europe via a post-glacial human population expansion before the Holocene (12 kya)13. Our data complement a recent study, based on present-day mt genomes, which describes a pronounced population increase at ~7000 BC (interpreted as a Neolithic expansion into Europe), but followed by a slow population growth until the present day26. By including ancient DNA data from across the critical time points in question, our skyride plot corrects for missing temporal data and suggests substantial growth of hg H from the beginning of the Neolithic and continuing throughout the entire Neolithic period. This emphasizes the role of farming practices and cultural developments in the demographic expansions inferred in subsequent time periods, which have not yet been explored genetically.Nature Communications 4, Article number: 1764 doi:10.1038/ncomms2656
Neolithic mitochondrial haplogroup H genomes and the genetic origins of Europeans
Paul Brotherton et al.
Haplogroup H dominates present-day Western European mitochondrial DNA variability (>40%), yet was less common (~19%) among Early Neolithic farmers (~5450 BC) and virtually absent in Mesolithic hunter-gatherers. Here we investigate this major component of the maternal population history of modern Europeans and sequence 39 complete haplogroup H mitochondrial genomes from ancient human remains. We then compare this ‘real-time’ genetic data with cultural changes taking place between the Early Neolithic (~5450 BC) and Bronze Age (~2200 BC) in Central Europe. Our results reveal that the current diversity and distribution of haplogroup H were largely established by the Mid Neolithic (~4000 BC), but with substantial genetic contributions from subsequent pan-European cultures such as the Bell Beakers expanding out of Iberia in the Late Neolithic (~2800 BC). Dated haplogroup H genomes allow us to reconstruct the recent evolutionary history of haplogroup H and reveal a mutation rate 45% higher than current estimates for human mitochondria.