Iceland’s 1000-Year Genetic Shift
The Icelandic population has seen a very rapid change in their genetic material over the last millennia, according to new research. The study, which was published at the beginning of this month by the University of Iceland and deCODE Genetics, analysed genomes from 27 ancient Icelanders and compared them to those of their modern descendants. They found that present-day Icelanders have a much greater frequency of Scandinavian genes than the founding fathers of the country.
Iceland is thought to have been settled between 870 and 930 AD by Vikings travelling west from Northern Europe, along with other Scandinavian and British people they had enslaved. From this small founding group, the population remained relatively small (below 50,000) for a thousand years before expanding; today, the Icelandic population is roughly 330,000. The small number of founders and the lack of significant population expansions have meant that much can be learned about the history of the country by studying Icelandic genomes.
Previous genomic studies of the relatively isolated Icelandic population have revealed a great deal of information about the genetic development of the country. A large proportion of this research has been driven by deCODE Genetics, a biopharmaceutical company in Reykjavik that was founded by Kári Stefánsson in 1996. These past studies have suggested that the genetic make-up of the population changed significantly over a short period of time, but this study has been able to determine just how fast this shift was.
The team, led by S. Sunna Ebenesersdóttir, carried out their study by analysing the whole genomes of the skeletal remains of 27 Icelanders found in burial sites across the country. Through archaeological and radiocarbon dating, they were able to ascertain that the bones were roughly 1000 years old, indicating that they were part of the early Icelandic generations. The 27 genomes revealed a combination of Norse (Norwegian and Swedish) and Gaelic (Scottish and Irish) heritage in roughly equal quantities. However, within the modern Iceland population, roughly 70% of genes present are the result of Norse ancestry. This shift indicates that the population underwent a significant genetic change within only 1100 years or so.
The research group also interrogated how this change may have occurred so rapidly. They found that it was likely the result of genetic drift over time, combined with recent migration from Scandinavian countries, particularly Denmark. The authors also suggested that societal pressure could have been a contributing factor; the majority of Gaelic founders were enslaved and thus might have demonstrated lower birth rates.
This study offers an interesting insight into how the Icelandic population may have developed, but there are some caveats to the research. For one, the authors have cautioned that because their sample size was so small, it may not be representative of the overall population. Further, as those of Gaelic descent are likely to have been slaves, they are less likely to have been buried in well-marked graves and thus could be underrepresented in this study. In order to draw firm conclusions, the authors of the paper have stated that analysis needs to be done with a greater sample of ancient Icelanders.