Genetic snapshot of Icelandic population 1000 years ago published
21 January 2009
deCODE genetics has presented the results of the largest study of
ancient DNA from a single population ever undertaken. Analyzing
mitochondrial DNA, which is passed from mother to offspring, from 68
skeletal remains from approximately 1000 years ago, the study provides
the most detailed look to date at how a contemporary population differs
from that of its ancestors.
The results confirm previous deCODE work that used genetics to test
the history of Iceland as recorded in the sagas. These studies
demonstrated that the country seems indeed 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 1100 years ago.
Perhaps the most remarkable finding of the study is 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 more closely related to the present day populations of
Scotland, Ireland and Scandinavia, as well as those of northwestern
Europe and even southwestern Europe, than they are to present day
Icelanders.
This is an important demonstration of a phenomenon known as 'genetic
drift.' In essence, 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. And as a result,
particularly in a small population, the genetic variety of the original
population can decrease and change over time.
In this study only mitochondrial DNA was studied, but the same
phenomenon applies to the Y chromosome, which is passed from fathers to
sons, and to any other part of the genome. The paper, Sequences from
first settlers reveal rapid evolution in Icelandic mtDNA pool, is
published in the open-access journal PLOS Genetics.
Kari Stefansson, CEO of deCODE said, "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. 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. In this field, as
in the genetics of common diseases, we are pleased and proud to be able
to put the knowledge we gain in Iceland to work for the benefit of
people everywhere."
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