Largest-to-Date Genetic Study of Ancient Icelanders Completed

Scientists have completed the largest study of ancient DNA from a single population ever undertaken. Examining mitochondrial DNA, which is passed from mother to offspring, from 68 skeletal remains, the study provides a detailed look at how a modern population differs from that of its ancestors.

The researchers, from various institutions in Europe and Iceland, which include the University of Iceland (Reykjavik, Iceland); Institute of Evolutionary Biology (UPF-CSIC; Barcelona, Spain); Leiden University Medical Center (Leiden, The Netherlands); National Museum of Iceland (Reykjavik, Iceland); and the biotech company deCODE Genetics (Reykjavik, Iceland), reported that the study's results validate earlier deCODE research that used genetics to test the history of Iceland as recorded in the sagas. These studies demonstrated that the country seems to have been settled by men from Scandinavia--the Vikings--but that the majority of the original female inhabitants were from the coastal regions of Scotland and Ireland, areas that regularly suffered raids by Vikings in the years around the settlement of Iceland 1,100 years ago.

The current study additionally reveals that the gene pool of contemporary Icelanders appears to have evolved rapidly over the intervening thousand years. As a result, the original female settlers are genetically less closely related to present-day Icelanders, and instead more closely related to the present day populations of Scotland, Ireland, and Scandinavia, as well as those of northwestern and southwestern Europe.

This is a demonstration of a phenomenon known as "genetic drift.” In any population certain individuals will have more offspring, and by chance and in this case over the course of 35 generations, many more descendants than others. Moreover, as a result, specifically in a small population, the genetic variety of the original population can decrease and change over time. In this study only mitochondrial DNA was evaluated, but the same phenomenon applies to the Y chromosome, which is passed from fathers to sons, and to any other part of the genome.

"This study is a major contribution to the use of ancient DNA studies in tracing the history not just of single populations, but of our species and how we spread from Africa to every corner of the globe,” said Kari Stefansson, CEO of deCODE. "It is the first such study to be large enough to permit meaningful statistical methods to be applied to ancient DNA. We very much hope this will aid and encourage others to follow with large studies in other parts of the world.”

The study was published January 16, 2009, in the journal Plos Genetics.

Related Links:
University of Iceland
deCODE Genetics