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Friday, July 17, 2015

Iron Age and Anglo-Saxon genomes from eastern England (Schiffels et al. preprint)


I haven't read this properly yet, but the results appear to be very similar to those I obtained with some of the same ancient genomes (see here), which must be very heartening for the authors (j/k). By the way, it's interesting to note that the word Celtic doesn't appear anywhere in the paper. I wonder why?

British population history has been shaped by a series of immigrations and internal movements, including the early Anglo-Saxon migrations following the breakdown of the Roman administration after 410CE. It remains an open question how these events affected the genetic composition of the current British population. Here, we present whole-genome sequences generated from ten ancient individuals found in archaeological excavations close to Cambridge in the East of England, ranging from 2,300 until 1,200 years before present (Iron Age to Anglo-Saxon period). We use present-day genetic data to characterize the relationship of these ancient individuals to contemporary British and other European populations. By analyzing the distribution of shared rare variants across ancient and modern individuals, we find that today’s British are more similar to the Iron Age individuals than to most of the Anglo-Saxon individuals, and estimate that the contemporary East English population derives 30% of its ancestry from Anglo-Saxon migrations, with a lower fraction in Wales and Scotland. We gain further insight with a new method, rarecoal, which fits a demographic model to the distribution of shared rare variants across a large number of samples, enabling fine scale analysis of subtle genetic differences and yielding explicit estimates of population sizes and split times. Using rarecoal we find that the ancestors of the Anglo-Saxon samples are closest to modern Danish and Dutch populations, while the Iron Age samples share ancestors with multiple Northern European populations including Britain.

Schiffels et al., Iron Age and Anglo-Saxon genomes from East England reveal British migration history, bioRxiv, Posted July 17, 2015. doi: http://dx.doi.org/10.1101/022723

21 comments:

Mike Thomas said...

Excellent study. Certainly will help refine theories on the cultural change and migration in post-Roman England.


But that 'today’s British are more similar to the Iron Age individuals than to most of the Anglo-Saxon individuals," suggests that there was some 'revival' of 'Brittonic' ancestry, again (like in post-Neolithic Europe) by a completion of admixture between 'natives' and 'newcomers'.

But I wonder how fitting in the BB, Unetice & BA Scandinavian Samples we have will affect the conclusions. As they might serve better proxies for "Anglo-Saxons' than modern Norweigans, Dutch.

rozenfag said...

Regarding proxy for Anglo-Saxons, we have RISE174 from Allentoft. It's from Malmo, 427-611 AD.

Colin Welling said...

it's interesting to note that the word Celtic doesn't appear

Probably because the geneticists should stay out of cultural interpretations for the most part. Of course they use terms like iron age but that is pretty basic...

Colin Welling said...

from the abstract

Using rarecoal we find that the ancestors of the Anglo-Saxon samples are closest to modern Danish and Dutch populations

I wonder why the eastern English have an estimated 30 percent anglo saxon, a component which is closest to Danish and Dutch, but the recent fine scale study on only modern samples estimates that the danish contribution to enland was small.

Graham Little said...

So the Early Anglo-Saxons are closest to the modern ( North?) Dutch & the Mid Anglo Saxons in England are closer to the Danish.

The 3 Iron Aged Brythonics have a North European base. Probably something like WHG which shows on Hinxon4's Eurogenes K8.



Mike Thomas said...

My initial impression is that actual A-S migration was more in the order of 50% +.
Certainly, unless one falls back onto ken Dark's arguements of "archaeological invisibility", a case of mass migration from Nth Europe cannot be denied, more so by the contemporous abandonement of setlements in coastal Netherlands, and the north Sea littoral generally.

I suspect, only direct comparison of ROman and post-Roman aDNA from both England and north Europe will aproximate true figures. Why ? Becuase modern Dutch & Danes might bare some ancestry of more southern arrivals in the post-400 AD period

Simon_W said...

Agreed, excellent paper.

This should answer the questions Apostatesimpressions was longing for: The British are predominantly of Insular Celtic descent, with the Germanic contribution being in the minority, though still substantial in certain places and individuals (up to 40% in East English individuals).

To me it's surprising that the Anglo-Saxon ancestry is quite evenly distributed in Britain, around 30% in eastern England, but still around 20% in Wales and Scotland. This certainly suggests a high amount of internal migration and mixture after the Anglo-Saxon incursions. Perhaps this occured rather recently, after the industrialisation.

The different affiliations of Anglo-Saxon individuals, with some being closer to the Dutch and others to the Danes, might perhaps reflect different tribal affiliations, the former Saxon, the latter Angles.

Simon_W said...

@ Rozenfag

RISE174 as a proxy for Anglo-Saxons? I don't think so. He's too eastern! The Angles and Saxons were from Jutland and the North Sea area of Germany. RISE174 may rather serve as a proxy for the early ethnic Danes who moved to Jutland after part of the Angles had left for England.

Indeed, this is what the Eurogenes K15 oracle suggests: Judging from the oracle, the Hinxton Anglo-Saxons resemble Orcadians, West Norwegians and the Northern Dutch. While RISE174 resembles modern Danes, or a West Scottish + Swedish/Estonian mix, clearly bearing testimony to its more eastern origin. On the other hand, RISE71, who is from Late Neolithic Jutland, resembles a mix of 67% West Norwegian + 33% Orcadian, exactly like some of the Anglo-Saxons at Hinxton. So, concluding from this, there was an east-west structure among these Germanics, and Jutland was already Anglo-Saxon-like in the Late Neolithic.

But anyway, we don't need a proxy for Anglo-Saxons, because according to this new paper it's possible to spot the Anglo-Saxons with local British ancestry and to tell them apart from the pure ones.

Simon_W said...

BTW, North Germans have not been included in the comparisons in the paper, but I've noticed before that the Northern Dutch and the Danes are better proxies for my East Prussian grandmother's Medieval Northwest German ancestry than the Eurogenes North German sample, while Hinxton Anglo-Saxons make the best fit. With 4mix, using K15 data:

0% North_German + 71% North_Dutch + 6% Polish + 23% Lithuanian @ D = 5.6414

0% North_Dutch + 74% Danish + 0% Polish + 26% Lithuanian @ D = 5.0612

27% Hinxton2 + 42% Hinxton5 + 12% Polish + 19% Lithuanian @ D = 4.0359

rozenfag said...

@Simon_W

Ok, I should have said differently. Basically RISE174 is closest in time and space to Iron Age Britons and Anglo-Saxons. Here is the map with available samples from Iron Age Europe:

https://img-fotki.yandex.ru/get/11/54029168.5b/0_9b486_1418807a_orig.png

As you can see RISE174 is closest geographically to Britain.

Graham Little said...

A larger proportion of the Anglo Saxon in the Scots 20% may have actually came from the Norse.. Whereas the 30% in Eastern England literally is Anglo Saxon.

Chad Rohlfsen said...

Some good news. Y-full is updating their tree in the next 1-3 days. 468 new SNPs, 97 new subclades. 72 and 35 respectively, for R1b.

Tobus said...

@Chad: (psst... that adds up to 107 :P)

Average Joe said...

I am surprised they didn't use any Irish samples.

Rokus said...

I wonder how the widely insinuated post-Roman Dutch or Frisian 'extinction' could hold against this new evidence brought forward of an effective
population being 'highest in the Netherlands (~210,000).' Indicates a pretty solid local continuity to me. Actually, I am not surprised at all that especially the earliest Anglo-Saxons seem to relate to the Dutch - whatever happened next, this order must have been critical to the linguistic direction of Anglo-Saxon.

Mike Thomas said...

Rokus
-Coastal Netherlands has near total abandonment of the landscape. More continuity further inland

Rokus said...

@Mike,

'Coastal Netherlands has near total abandonment of the landscape. More continuity further inland'
In that case the inland Dutch were attested in the Anglo-Saxon genes rather than the coastal Dutch? This doesnot make sense.
According to absence of evidence, for a landscape where rivers often changed their courses and floods and subduction changed sedimentation patterns. Some natural 'donks' or river dunes in the middle of flood plains show habitation back to the Beaker times. In other words: I think archeologists should restrain from hasty conclusions.

Mike Thomas said...

Of course they should
But the region has been extensively investigated. The "absence of evidence ..." arguement, in this case, is a non one.
But that's not my point. My pojnt was that the coastal Dutch "disappear " because they all ended up in England !

Nick T said...

@Mike,

Actually the current archaeological evidence suggests that the depopulation of parts (but not all) of the Netherlands (e.g. many terp sites)occurs too early to relate to post-Roman population movements into Britain. Referring to Nieuwhof's recent article in the Journal of the Archaeology of the Low Countries, for example, that refers to sites being abandoned by 300 AD, and re-occupation occurring in the 5th century AD, with Anglo-Saxon pottery. So Anglo-Saxons, if one can use a pots=people equation, are moving into the coastal area of the Netherlands in the C5 AD, not out of it.

Mike Thomas said...


Nick you're right about the earlier commencement of depopulation, but I thought the max flux was in late 4th. And I think AS type pottery in the 5th was still small in amount. Also *continental* Saxon pottery begins to appear. But I certainly take your points. Perhaps I need to revisit the latest datings, and see what they've come up with dendrodates..

weure said...

@rozenfag, I guess you've got a point here with the reference to RISE174
I'am of North Dutch stock, and a polish guy plotted me very well: "You plot on my PCA very close to "Germanic" average as well as to RISE174 (Iron Age Sweden), RISE61 (Early Bronze Denmark) and RISE94 (Early Bronze Sweden). In fact you plot closer to Early Bronze Age Swedes, than that modern Southern Swede."

@Simon W and here are my K13 and K15 results:

K13
Using 1 population approximation:
1 Danish @ 1.742467
2 North_Dutch @ 2.503399
3 Norwegian @ 2.936815
4 North_German @ 4.368844
5 Orcadian @ 4.697951
6 Swedish @ 4.926437
7 Irish @ 5.600447
8 West_Scottish @ 6.118611
9 Southeast_English @ 6.190817
10 Southwest_English @ 7.859173

Using 2 populations approximation:
1 50% Danish +50% Norwegian @ 1.723689

Using 3 populations approximation:
1 50% Danish +25% Danish +25% Norwegian @ 1.494796

K15

Using 1 population approximation:
1 North_Dutch @ 2.662666
2 Danish @ 3.078913
3 West_Scottish @ 4.199471
4 Orcadian @ 4.770091
5 Norwegian @ 4.771307
6 Irish @ 4.923634
7 West_Norwegian @ 5.078017
8 Southeast_English @ 6.210367
9 Swedish @ 6.318136
10 North_German @ 6.876086
Using 2 populations approximation:
1 50% Norwegian +50% West_Scottish @ 1.545855


Using 3 populations approximation:
1 50% Irish +25% Norwegian +25% West_Norwegian @ 1.528969

Using 4 populations approximation:
1 Swedish + West_Norwegian + West_Scottish + West_Scottish @ 1.415054