Monday, January 4, 2016

Irish Ancient DNA from Rathlin Island and Ballynahatty

Neolithic and Bronze Age migration to Ireland and establishment of the insular Atlantic genome.

PNAS
Edited by Montgomery Slatkin, University of California, Berkeley, CA, and approved November 18, 2015 (received for review September 18, 2015)
Lara M. Cassidy, Rui Martiniano, Eileen M. Murphy, James Mallory, Barrie Hartwell, Daniel G. Bradley
(Link)

Abstract
The Neolithic and Bronze Age transitions were profound cultural shifts catalyzed in parts of Europe by migrations, first of early farmers from the Near East and then Bronze Age herders from the Pontic Steppe. However, a decades-long, unresolved controversy is whether population change or cultural adoption occurred at the Atlantic edge, within the British Isles. We address this issue by using the first whole genome data from prehistoric Irish individuals. A Neolithic woman (3343–3020 cal BC) from a megalithic burial (10.3× coverage) possessed a genome of predominantly Near Eastern origin. She had some hunter–gatherer ancestry but belonged to a population of large effective size, suggesting a substantial influx of early farmers to the island. Three Bronze Age individuals from Rathlin Island (2026–1534 cal BC), including one high coverage (10.5×) genome, showed substantial Steppe genetic heritage indicating that the European population upheavals of the third millennium manifested all of the way from southern Siberia to the western ocean. This turnover invites the possibility of accompanying introduction of Indo-European, perhaps early Celtic, language. Irish Bronze Age haplotypic similarity is strongest within modern Irish, Scottish, and Welsh populations, and several important genetic variants that today show maximal or very high frequencies in Ireland appear at this horizon. These include those coding for lactase persistence, blue eye color, Y chromosome R1b haplotypes, and the hemochromatosis C282Y allele; to our knowledge, the first detection of a known Mendelian disease variant in prehistory. These findings together suggest the establishment of central attributes of the Irish genome 4,000 y ago.

Figure S12.1. Outgroup f3-Statistics for each ancient Irish Individual. Tests in the form f3(Mbuti; IA, X), where IA is an Irish ancient genome and X is any other ancient individual or population. Data points are coloured by archaeological context
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Some observations about this paper:
 
This paper introduces four new samples for Ireland, as follows: 
 
1. Rathlin Island (three samples)
2. Ballynahatty (one sample)
 
For the Rathlin Island samples, it is indeed interesting that their male Y-chromosome haplogroups are R1b-M529.  That establishes a predominate y-chromosome haplogroup in the British Isles today as dating from 2026–1534 cal BC (at a minimum).
 
Looking at Figure S12.1, (D statistics tables, above), you see that the Rathlin samples compare most strongly with the Yamnaya, Samara hunter gatherers, Sintashta hunter gatherers, German Bell Beaker, Halberstadt, Unetice, Alberstedt, Scandinavian hunter-gatherers, Hungarian Bronze Age and Neolithic samples, and Loschbour (western European hunter gatherer).
 
It's really a hodge podge that does not immediately suggest a simple Bronze Age Russian Steppe origin. Archaeology doesn't suggest this either, at least according to the work of Terberger, Zhilin and Hartz (http://www.quartaer.eu/pdfs/2010/2010_hartz.pdf).  Their paper, and the Rathlin Island DNA, suggest a complex prehistory for the ancestors of Rathlin Island in which their upstream ancestors possibly stem from Maglemosian, Ertebolle, Narva, German Bell Beaker, Scandinavian Hunter Gatherers and related cultures, Czech and Hungarian Bronze Age and Neolithic cultures, and/or from the Russian Steppe cultures (not necessarily in the Bronze Age.)  In fact, two closely related cultures to the Rathlin Islanders are from Samara and Sintashta in Russia.  These hunter-gatherers are from a much earlier context than Yamnaya.
 
The Mesolithic of Britain is not well understood, especially in Scotland. New sites are turning up all the time. For instance, a significant Hamburgian Havalte site was just excavated in the last five years (http://www.lithicresearch.co.uk/scotlands.html).  And there is some preliminary evidence for a Maglemosian in Scotland. Nothing definitive here, but there is certainly enough recent archaeological evidence for a longstanding Mesolithic in the UK and Northwestern Europe to beg for consideration of a more complex model than a two step model of Neolithic farmers followed by an invasion of Bronze Age Steppe herders from Russia.
 
Genetically speaking, Ertebolle, Maglemosian, Funnelbeaker and other cultures could look quite similar, so it could be difficult to disentangle the long and complex history of Western Europe.  The Funnelbeaker culture itself is a highly complex archaeological horizon that does not fit into neat classification.  It would be presumptuous to assume that the Funnelbeaker culture could be represented by a single sample (Thus far, Gok2 is the only ancient DNA from a Funnelbeaker context).

Similarly, the precursors to the Bell Beaker culture are not well understood.  It has been suggested recently by Wolfgang Haak et al (2015), that the precursor to the Bell Beaker culture is the Yamnaya culture.  However, others such as Allentoft et al (2015) are more measured in their predictions about the genetic prehistory of the Bell Beaker culture.

Regarding the Ballynahatty sample, it's exciting to see evidence for the origin of the Neolithic in Ireland.  The paper shows a clear relationship with modern populations in Iberia, Sardinia and Corsica and the Ballynahatty sample.  It certainly supports a long suspected relationship between the Megalithic of Ireland (think Knowth) and the Megalithic of Iberia and France:

Figure 3. Comparison of Irish and Hungarian genomes for haplotype-based affinity to modern populations.

 
 
Figure 3 also has an interesting plot for the relationship between a Neolithic sample from Hungary and modern populations:

It is unfortunate that this paper suggests, in the abstract, that the ultimate origin for the European Neolithic is in the "Near East".  Also unfortunate was the prominent Guardian article on this paper:  Irish DNA originated in Middle East and eastern Europe.  In fact, most evidence to date indicates that the origin for the early European Neolithic is in Greece, the Southern Balkans and Anatolia.   The terms "Near East" and "Middle East" are Western European terms used to refer to countries east of Greece.  These terms were not used in Greece, the Balkans, or Turkey before the 20th century, and were not used anywhere in the Ottoman or Byzantine world.  The last time I checked, Greece was in Europe.  In fact, the origin for the word Europe is Ευρώπη.
 
In an archaeological context, "Near East" and "Middle East" are meaningless terms.  Hopefully, genetic anthropologists and those publishing material on ancient DNA studies will in future avoid the use of these confusing terms when discussing the origin of the Neolithic.

In spite of the above reservations, this paper has a lot of detailed material with very good graphs and analysis.

It will be interesting to see what this group takes on next.  Maybe the precursors to Bell Beaker?

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