The role of recent admixture in formingthe Contemporary West Eurasian Genomic Landscape

Early Medieval Europeans were Migrants

Europe is inhabited by descendants of migrants, who moved around in the first millennium AC. Later people stopped mingling so much.

Europe is presently trying to cope with a wave of migrants from Africa, the Levant and East Asia. This is nothing new. Genetic studies are helping us to understand a corresponding mixing of people, which took place in the first millennium. It was massive.

Tracing our ancestry through genetic studies is not for the faint-hearted. To be quite honest: we have to take the published results of genetic scientists as the gospel truth as we (mere mortal historians and archaeologists) seldom have the technical capacity to critically review the exact scientific procedures or methods by which their conclusions are reached. On the other hand, there is no reason to seriously doubt their conclusions, when properly published in important peer-reviewed journals. As is the case with the latest paper published in Current Biology, which stems from an international group of scientists funded by amongst others the Wellcome Trust, the John Fell Fund and the British Academy.

In this article, the scientists have studied the traces of earlier admixture in the genetic profiles of 1235 modern Europeans. Genetic admixture occurs when individuals from two or more previously separated populations begin interbreeding. Admixture results in the introduction of new genetic lineages into a population.

The old-fashioned Historical way of depicting the migration of the Visigoths. Source. Wikipedia
The old-fashioned way of depicting the migration of the Visigoth as a narrow series of one-time events. Source: Wikipedia

By identifying and characterizing the exact mixture of the genetic chunks in a given individual and measuring and comparing the level of the decay between the different chunks, it seems to be possible not only to discover from where these chunks were originally sourced but also to date the exact time-frame inside which the admixture – popularly speaking coupling, love-making and mixing of gene-pools – took place.

It stands to reason that the results are only preliminary. Studies of much larger groups of people should be carried out in order to measure the exact character and impact of ancient copulating in any given modern population. This might also shed more precise information on the timeframe in which the admixture – or rather the series of events, which led to the current genetic make-up of a given population – took place. However, the present conclusions are rather illuminating:

1) In the paper the scientists attempt to quantify whether the genetic diversity of Europeans increased or decreased as a result of mixing. There is some evidence that suggests that admixture homogenises populations, and so makes them more similar. However, the scientists did not find this trend. In fact they saw instead a hint that admixture had increased differentiation between groups (or at least maintained differentiation). This is what they refer to as the impact of admixture, which they characterize as significant.

2) First of all an important admixture took place in Eastern Europe following an influx of people from primarily Mongolia, setting its distinct mark on Russia, Caucasus and Turkey. Looking at the population in South Western Europe this was defined by an influx of people from the Levant and Africa. Finally, North Siberians set their mark on Finland. Apart from this, North-Western Europe cannot be characterized by any admixture, sourced from the outside of present Europe. It appears that at this point in history people in North-Western Europe lived their own lives. These events took place early on – during the Bronze Age, but of course also later.

3) However, looking at the admixture which took place inside Europe – that is, sourced by different European people – and the timeframe, in which this took place, the snap-shot gets really complicated. Within Northern, Western, and Central Europe, complicated patterns of admixture tended to occur between local groups and swarms of migrants during the period 300 to 1200 CE, concludes the scientists.

4) Apparent is also that the admixture, which took place was probably not a one-time event. Admixture was the result of a long series of events, which took place inside long periods of time (up to a millennium).

5) After 1250 this moving around seemed to stop in Western Europe. However, in Central Europe people continued to move from the North to the South as did the Turks and the Armenians, which continued to arrive in South-Western Europe until post-reformation.

Thus looking at the population in North-Western Europe and more specifically Great Britain, the genetic profile of the population there is the result of a proportion of admixture between locals and German migrants measuring more than 50%. This admixture (coupling) took place from AD 241-1241 and reverberated into Norway and France (and back again). Thus it does not necessarily imply a large-scale (once-in-a millennium) type of event. Rather, it might very well be the result of a steady trickling of migrants into the British Isles and further on.

Looking at the maps provided by the scientists it becomes obvious that there were three regions in first millennium Europe through which people moved A) the Northern European Baltic/North Sea Region reaching from Ireland to Finland B) The Southern European/Mediterranean region with people moving from the East to the West and finally C) Central and Eastern Europe fed by a gene-pool situated in Lithuania.

“The date and composition of these events suggest a substantial amount of movement during the “Völkerwanderung”, providing persuasive evidence that this period had a visible effect on contemporary populations across Northern, Western, and Central Europe”, writes the scientists in their conclusion.

What is perhaps also important to note is that these movements of people seem to have generated a level of admixture measuring between 20 – 50% (or more) indicating that these movements had a size, which was able to generate a significant impact on the composition and character of the gene-pool of people living in different parts of Europe, even today.

It seems more and more evidence is piling up against the archaeologists, who have for so long argued that no significant migration did in fact take place in first millennium Europe. On the other hand evidence is also piling up against historians, who believe that migration was limited to specific large-scale events like the crossing of The Rhine in AD 406. It seems rather that migration of people was a fundamental feature of Early Medieval Europe until at least 1250. And continued longer in South Eastern Europe.

However, what also becomes obvious is that these events were not one-off stands. Through the Early Middle Ages people moved along specific vectors in the European landscape creating regional European gene-pools, which might then be “exported” further. In the later Middle ages this effectively stopped apart from the Turkish and Armenian migration into South-Eastern Europe and the Lithuanian migrationary movement to the South.


The Role of Recent Admixture in Forming the Contemporary West Eurasian Genomic Landscape
By George B.J. Busby et al.
In Current Biology (2015) Vol 25; pp. 1 -9 ,


The fine-scale genetic structure of the British population
By Stephen Leslieet al.
In: Nature 2015, vol. 519, 309–314


The map (4C) illustrates how specific chunks of DNA “moved” through time and space and created a European map, characterised by genetically diversified regions. These regions were marked out through the history of series of specific events of admixture. The regions – areas of intense contact – were initially peopled by humans moving back and forth, while breeding. Later the regions “froze” (people started “inbreading”). The arrows show the direction and intensity of these Early Medieval movements. The legend explains the time-frames in which this admixture took place. Published in: The Role of Recent Admixture in Forming the ContemporaryWest Eurasian Genomic Landscape and rendered here by kind permission. © The Authors.



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