The puzzle of the early Corded Ware grave

In a recent paper and talk, archaeologist Kristian Kristiansen mentions a very early Corded Ware (CW) burial in Tiefbrunn, Germany; one of a few that contain a hammer-headed bone pin, like those found in Yamnaya and Catacomb graves on the steppe, particularly in the North Caucasus region.

Sr isotope ratios suggest that the older man was non-local, while the young man and the child may be locals. The skulls of all three individuals exhibited signs of severe trauma and they had probably suffered violent deaths. … The grave goods consisted of only a flint blade and a hammer-headed bone pin, laid down beside the older male. Such pins are rare in the CW of Central Europe, but common in the Pontic Steppe region where they occur in a variety of forms until they disappear around 2600 BC [38].

All three individuals from this grave had their genomes sequenced as part of The Rise project and were labeled RISE434, RISE435 and RISE436. This is how they cluster in my Principal Component Analysis (PCA) of ancient West Eurasia.

As far as I can tell, based on the Sr isotope ratios from Sjögren K-G, Price TD, Kristiansen K 2016, RISE436 is the older man with the pin and RISE434 the young man (see here). But if so, what is the likely non-local RISE436 doing as the most western of the Corded Ware samples sequenced to date? And why are the potentially local RISE434 and RISE435 so much more Yamnaya-like than him? My interpretation of these results is that RISE436 was the descendant of a proto-Corded Ware male migrant from the steppe, and that his mother may have been of pre-Corded Ware farmer stock from Central or East-Central Europe. Note that this individual belongs to the Eastern European Y-chromosome haplogroup R1a, Western European (?) mitochondrial haplogroup U5b1c2, and on the plot above clusters almost exactly half-way between Yamnaya and early European farmers (Europe_EN and Europe_MN). On the other hand, the young man and infant may derive from a more fully developed Corded Ware community in Central Europe, largely made up of second and third generation migrants from the steppe. Any other ideas? Citations… Sjögren K-G, Price TD, Kristiansen K (2016) Diet and Mobility in the Corded Ware of Central Europe. PLoS ONE 11(5): e0155083. doi:10.1371/journal.pone.0155083 Allentoft et al., Population genomics of Bronze Age Eurasia, Nature 522, 167–172 (11 June 2015) doi:10.1038/nature14507

Source Eurogenes Blog