Anthropologist Sunna Ebenesersdóttir, of the University of Iceland and the company deCODE Genetics in Reykjavik, analysed the genomes of 25 ancient Icelanders whose skeletal remains were found in burial sites across the island.
Sequencing using samples from teeth revealed the settlers had a roughly even split of Norse (from what are today Norway and Sweden) and Gaelic ancestry. It is the first in-depth investigation of how a new population is formed through a genetic process known as "admixture".
When the researchers compared the ancient genomes to those of modern people in Iceland and other European countries, they found contemporary Icelanders, on average, draw about 70 per cent of their genes from Norse ancestry.
This suggests that in the 1,100 years between settlement and today, the population underwent a surprisingly quick genetic shift in favour of Norse genes, the researchers report in the journal Science.