Update 9/10/2014: Analysis of an ancient genome from Hinxton
This is arguably one of the most intriguing abstracts from next month's ASHG 2014 conference:
Insights into British and European population history from ancient DNA sequencing of Iron Age and Anglo-Saxon samples from Hinxton, England. S. Schiffels, W. Haak, B. Llamas, E. Popescu, L. Loe, R. Clarke, A. Lyons, P. Paajanen, D. Sayer, R. Mortimer, C. Tyler-Smith, A. Cooper, R. Durbin.
British population history is shaped by a complex series of repeated immigration periods and associated changes in population structure. It is an open question however, to what extent each of these changes is reflected in the genetic ancestry of the current British population. Here we use ancient DNA sequencing to help address that question. We present whole genome sequences generated from five individuals that were found in archaeological excavations at the Wellcome Trust Genome Campus near Cambridge (UK), two of which are dated to around 2,000 years before present (Iron Age), and three to around 1,300 years before present (Anglo-Saxon period). Good preservation status allowed us to generate one high coverage sequence (12x) from an Iron Age individual, and four low coverage sequences (1x-4x) from the other samples. By providing the first ancient whole genome sequences from Britain, we get a unique picture of the ancestral populations in Britain before and after the Anglo-Saxon immigrations. We use modern genetic reference panels such as the 1000 Genomes Project to examine the relationship of these ancient samples with present day population genetic data. Results from principal component analysis suggest that all samples fall consistently within the broader Northern European context, which is also consistent with mtDNA haplogroups. In addition, we obtain a finer structural genetic classification from rare genetic variants and haplotype based methods such as FineStructure. Reflecting more recent genetic ancestry, results from these methods suggest significant differences between the Iron Age and the Anglo-Saxon period samples when compared to other European samples. We find in particular that while the Anglo-Saxon samples resemble more closely the modern British population than the earlier samples, the Iron Age samples share more low frequency variation than the later ones with present day samples from southern Europe, in particular Spain (1000GP IBS). In addition the Anglo-Saxon period samples appear to share a stronger older component with Finnish (1000GP FIN) individuals. Our findings help characterize the ancestral European populations involved in major European migration movements into Britain in the last 2,000 years and thus provide more insights into the genetic history of people in northern Europe.
So in other words, the Iron Age Britons, presumably of Celtic origin, share inflated levels of rare (ie. low frequency) alleles with Spaniards. Assuming these are pre-Roman samples, and it does seem that way, then the results suggest there were direct genetic ties between the British Celts and Mediterranean populations even before the Romans crossed the channel. I wonder if this is the Bell Beaker pimp juice talking?
Conversely, the Anglo-Saxons are more Finnish-like. But I wouldn't read too much into this result, because Finns are the only northern European population from east of England in the 1000 Genomes project, so they're probably just acting as a proxy for gene flow from the far north of what is now Germany.
Interestingly, these signals aren't all that difficult to pick up in present-day English genomes. Below, for instance, are two sets of Eurogenes K15 ancestry proportions for English samples from Cornwall and Kent, respectively.
Note that both groups are typically Northwest European. However, the English from Cornwall are clearly more West Med, while those from Kent slightly more North Sea, Baltic and Eastern Euro. The West Med component peaks in Sardinia, but also occurs at relatively high frequencies in Iberia, while the North Sea, Baltic and Eastern Euro components are well represented among the Finns.
These differences aren't jaw dropping, but they're certainly noticeable. They also make prefect sense in the light of the ancient genomic data, because Cornwall is arguably one of the regions of the UK least affected by the Anglo-Saxon invasions. Kent, on the other hand, was settled by the Jutes during the 5th century. These people weren't Anglo-Saxons, but nonetheless a very similar Germanic tribe from the Jutland Peninsula.
English from CornwallSee also...
English from Kent
Corded Ware Culture linked to the spread of ANE across Europe