The results of a long term study of  human genetics into the nature of the evolutionary processes that have shaped the gene pools of modern populations has been revealed.

While examining the genetic origins of Icelandic families, researchers who include Carles Lalueza-Fox from IDEC-Universitat Pompeu Fabra in Spain, have claimed that the first Americans reached Europe a full five centuries before Christopher Columbus set off on his first voyage of discovery in 1492. Experts from the Centre for Scientific Research, are convinced that a woman from the Americas arrived in Iceland 1,100 years ago, leaving behind genes that are reflected in nearly 100 Icelanders today.
Although most mtDNA lineages observed in contemporary Icelanders can be traced to neighbouring populations in the British Isles and Scandinavia, one may have a more distant origin. This lineage belongs to haplogroup C1, one of a handful that was involved in the settlement of the Americas around 14,000 years ago. Contrary to an initial assumption that this lineage was a recent arrival, preliminary genealogical analyses revealed that the C1 lineage was present in the Icelandic mtDNA pool at least 300 years ago.

Experts from the Centre for Scientific Research, are convinced that a woman from the Americas arrived in Iceland 1,100 years ago

Due to a faster rate of genetic drift in the Icelandic mtDNA pool during the last 1,100 years, the sequences carried by the first settlers were better preserved in their ancestral gene pools than among their descendants in Iceland.
In the article published in the American Journal of Physical Anthropology it is stated that “This raised the intriguing possibility that the Icelandic C1 lineage could be traced to Viking voyages to the Americas that commenced in the 10th century. In an attempt to shed further light on the entry date of the C1 lineage into the Icelandic mtDNA pool and its geographical origin, we used the deCODE Genetics genealogical database to identify additional matrilineal ancestors that carry the C1 lineage and then sequenced the complete mtDNA genome of 11 contemporary C1 carriers from four different matrilines. Our results indicate a latest possible arrival date in Iceland of just prior to 1700 and a likely arrival date centuries earlier. Most surprisingly, we demonstrate that the Icelandic C1 lineage does not belong to any of the four known Native American (C1b, C1c, and C1d) or Asian (C1a) subclades of haplogroup C1. Rather, it is presently the only known member of a new subclade, C1e. While a Native American origin seems most likely for C1e, an Asian or European origin cannot be ruled out. “
They  discovered the genes could be traced to common ancestors in the south of Iceland, near the Vatnajökull glacier, in around 1710, ruling out initial theories that they may have arrived via Asia – as this was long before Asian genes appeared in Icelanders.
“As the island was practically isolated from the 10th century onwards, the most probable hypothesis is that these genes correspond to an Amerindian woman who was taken from America by the Vikings some time around the year 1000,” said Carles Lalueza-Fox, of the Pompeu Fabra university in Spain.
Norse sagas suggest Scandanavians discovered the Americas, and the latest data seems to support the hypothesis that they may have brought American Indians back with them to northern Europe.
A Norse settlement at L’Anse aux Meadows, in the Canadian province of Newfoundland and Labrador, is thought to date to the 11th century, which would match the approximate date of this rough wooing.
Researchers said they would keep trying to determine when the Amerindian genes first arrived in Iceland and would seek to link them to burial remains in the Americas.