Recently in Washington D.C. at the International Conference for Genetic Genealogy Spencer Wells ran through a survey of personal genomics, and asserted that over the past year we’ve nearly doubled the number of genotypes on dense marker arrays, from ~1 million to nearly ~2 million. Talking to people that seems about right, 23andMe is approaching the million mark itself alone. Combined with the databases of National Geographic, Ancestry and Family Tree DNA the 2 million mark is surely approaching us. But the presentation wasn’t simply about personal genomics today. He integrated the modern changes to events which occurred over the past generation to bring genetics to the people, and allow its widespread utilization among researchers to explore historical questions. Coming out of the Human Population Genetics Lab at Stanford in the 1990s Wells pointed out that the constituent populations of the HGDP were selected by L. L. Cavalli-Sforza consciously to be biased toward those which were more isolated and genetically less subject to globalization. The theory was to pick up stronger signals of ancient population structure which might be obscured by more recent movements of peoples across the earth.

MDS representation of Europeans, with a focus on Germans. Click to englage. Credit: Family Tree DNA

By and large Cavalli-Sforza’s intuition has been validated. The HGDP data set has yielded enormous insight, first with classical markers (see History and Geography of Human Genes), then during the Y and mtDNA era around 2000, as well as microsatellites and dense SNP arrays in the aughts. I’ve heard that the Sardinian samples that Cavalli-Sforza selected were somewhat less cosmopolitan than other Sardinians that have been collected later, indicative of his personal knowledge of Italian genetic variation on a personal level. But he also had the area knowledge to sample both the western and eastern Pygmy populations of the Congo. The evolutionary history separating these two groups is likely on the order of that dividing inter-continental populations outside of Africa, and the eastern Pygmies in particular are an invaluable reservoir of human genetic variation. To answer a few big questions a data set of 1,000 specially selected humans from across the world turns out to have been sufficient.

But there is a flip side. The answers to the many small questions are going to require much more sample coverage. Wells himself illustrates this reality, as he recounted a story from his Geno 2.0 database where a few percent of ethnic Hungarians exhibit Central Asian uniparental haplotypes. He points out that standard analyses don’t show anything special about Hungarians, but then again you are likely to miss admixtures on the order of a few percent here and there if you are working with sample sizes of less than 100, which is still typical for European nations. Even a large data set, such as the POPRES, is dwarfed by those of commercial firms and National Geographic.

Germany population density

Last week I reported that Afrikaners do seem admixed using the Family Tree DNA database. But that’s not the first strange thing that I saw. When devising myOrigins I had to attempt to tackle the problem of German ancestry and assigning individuals to a particular cluster. I was skeptical for a simple reason: the historical literature was clear that substantial numbers of Germans from the eastern zones of habitation were acculturated Slavs. But I was met with a surprise. Yes, the genetic variation showed substantial amount of admixture with Slavs. Using MDS/PCA you can see that there is an admixture cline with a Polish reference population for individuals who state that both their parents were born in Germany. But there is a second distinct cluster among Germans which overlaps with that of northern France. I don’t have data on the scale of specific geographic points, but my suspicion is that the region around Cologne is genetically distinct because of long-term gene flow with northern France. The scale of Hugenot migration to Germany in the 18th century seems unlikely to explain this.

On the scale of the “big questions” this is trivial and of minor note. But, to answer this sort of question about genetically close populations you need dense geographic coverage and large population sizes. Currently only the personal genomics firms have this, to my knowledge. POPRES and Framingham Heart Study both have sample sizes in the ~5,000 range total. 1000 Genomes is an improvement, but even its sample sizes and coverage is not sufficient. Where are we going? Spencer Wells talks a lot about citizen science. Many of the enthusiasts for scientific genealogy have done very deep analyses of their own genotypes. They certainly have skills to analyze bigger datasets. If computing power is needed then an Amazon cloud server could provide that. The problem though is that customer data can’t just be shared by the big companies themselves. In the short term the ultimate solution is to scale up projects, like Harappa DNA, and formalize their structure so that those who submit their genotype data are protected in some fashion (e.g., exposure of identity). Academic scholars are going to be focusing on whole genomes, more subtle methods, as well as exotic and obscure populations which can get at the big questions. To really see my point, see what Google Scholar returns when you type “genetic population structure germany”.

As a follow up to the previous post I’ve spent some of this weekend looking for the results which might shed some more light on the genetic impact of Germans on the British landscape between ~500-600 A.D. There are some problems here even assuming all other conditions are met: Northwest Europeans are already genetically rather close. This does not mean you can not distinguish an Irishmen from a German, but, once you take into account the clinal variation in gene frequencies due to isolation-by-distance models it becomes somewhat difficult to ascertain admixture in the spaces in between. After all, populations spatially between northern Germany and Ireland, the Brythonic Celts, are presumably going to be genetically between these two populations as well. That being said, space is not the only variable. Culture is another. The Celtic dialects spoken in Ireland and Britain are extremely distinctive, being of two branches of the broader language family, but there was still a clear resemblance between the two cultures (e.g., druids and other aspects of religion). In other words, the Celtiberians of Spain, the Galatians of Anatolia, the Gauls, and the various peoples of Britain in Ireland, all traded in a common cultural currency. Not only are they likely to have had some common ancestors, but there is going to be a dialect continuum across much of this cultural zone, facilitating continuous gene flow. And speaking of continuity, the fact that Britain is separated by water from the European mainland and Ireland is at least something that works in favor of genetic inferences, as that is a structural constant which mitigates in favor of distinctions and between group variation.

As I stated below, the ideal case would be a data set where you compare genetic variation as a function of geography within the British Isles (with linguistic information intact, so that Welsh speakers are labeled) against a north German reference. The problem with a pooled Northern European reference is that there’s also a “Finnic dimension,” which is pretty much irrelevant when you’re comparing Germans to British. And usually there isn’t the fine-grain that you’d want. Irish are not the ideal proxies for Brythonic Celts. Welsh, or perhaps Cornish or individuals from Devon, might be.

Quite often rather amusing articles which operate in the malleable zone between genetics and nationalism pop into my RSS feed (thanks to google query alerts). But this piece from Spiegel Online article, Britain Is More Germanic than It Thinks, actually appeals to some legitimate research in making a tongue-in-cheek nationalistic argument that the affinity between the Germans and the English is stronger than the latter would wish to admit. The article starts out with the interesting nationalist back story:

Until now, the so-called Minimalists have set the tone in British archeology. They believe in what they call an “elite transfer”, in which a small caste of Germanic noble warriors, perhaps a few thousand, placed themselves at the top of society in a coup of sorts, and eventually even displaced the Celtic language with their own. Many contemporary Britons, not overly keen on having such a close kinship with the Continent, like this scenario.

Thomas Sheppard, a museum curator, discovered this sentiment almost a century ago. In 1919, officers asked for his assistance after they accidentally discovered the roughly 1,500-year-old grave of an Anglo-Saxon woman while digging trenches in eastern England.

Sheppard concluded that the woman’s bleached bones came from “conquerors from Germany” and announced: “These are our ancestors!” But the soldiers were thunderstruck. At first they cursed and refused to believe that they were related to the “Huns.” But then the mood darkened. The trip back to the barracks “was like a funeral procession,” Sheppard wrote.

It is a coincidence which must be acknowledged that the vogue for Germanophilia amongst the English corresponds neatly to the decades when Irish nationalism waxed in the face of British imperial domination. And that Germanophilia naturally abated with the two World Wars. In lieu of the vision of Saxons, Angles, and Jutes, driving the Celtic British into the sea, Germanization was conceived as a process where an elite band of warriors imposed their culture atop a fundamentally pre-German substrate. This model is reflected in the historical scholarship, for example Norman Davies’ The Isles, as well as the genetics treatments, most prominently Bryan Sykes’ The Blood of the Isles.

In terms of the history, we have to make due with archaeology and the rather thin texts of the Celts. From what I can gather the archaeology does imply a rapid shift in material technology and symbolic aspects of culture such as burial customs on the Saxon Shore. Linguistically the modern English language owes very little to the Celtic dialects. Finally, the Christian Church seems to have disappeared across much of the zone of expanding German territory, only to be re-planted in the early 7th century by Irish & Scottish missionaries, followed up by those from the European mainland. In the Spiegel Online piece an archaeologist quotes a number of “200,000” for total migration for about a century, presumably inferring from the quantity of material remains, and what that implies about the numbers within the settlements which are indubitably German.

There are a few objections which crop up. Some scholars, such as Stephen Oppenheimer, argue that German speech was already common before the Roman conquest within the boundaries of England. Very few accept this position. A more mainstream argument is that like Gaul and Iberia much of Britain had been Latinized by the time of the German conquest. Because of their geographic isolation Cornwall, Scotland, and Wales, were the areas most insulated from both the German expansion and the dynamic of Latinization. Finally, some scholars have suggested that the outsiders get too much of the credit for the resurrection of the Christian Church in 7th century England, that an indigenous Christian culture persisted over the century of the British “Dark Ages” before the conversion of the Saxons.

The problem with each of these arguments is that they don’t cohere together very well. If Latin was the dominant language in Britain proper (i.e., outside of the “Celtic Fringe”) that begs the question why the Germans were not assimilated in Britain as they were in France and Iberia. Unlike the Saxons, Angles, and Jutes, the Frankish Empire was explicitly bicultural in that it spanned both Latinate Gaul and Germania. And yet the Franks who settled in Francia invariably adopted Latin and what later became French as their language. Additionally, Britain was one of only two regions of the Roman Empire where both the imperial languages (Latin and Greek) and the Christian Church disappeared with the barbarian invasion. The Balkans was the other zone.