Norse habitation in Iceland may have begun nearly 70 years prior to current historical estimates, with initial arrivals potentially having a less detrimental environmental effect than commonly believed.
Traditional historical accounts place the first permanent settlement of Iceland in the 870s AD. This period of migration is frequently characterized as an ecological catastrophe attributed to Viking raiders or Norse settlers who cleared the island’s forests for fuel, construction materials, and agricultural land. Today, forests cover a mere 2 percent of the country.
Establishing a definitive timeframe for the earliest settlers has presented challenges. While archaeologists have discovered an ancient wooden longhouse near the eastern fjord of Stöðvarfjörður, dating to approximately 874 AD, the underlying structure points to an even older site. This older longhouse is thought to represent a summer settlement from the 800s rather than a permanent residence, though this discovery has yet to be formally published in a scientific journal.
Environmental DNA Analysis Uncovers Earlier Human Presence
In a significant development, Eske Willerslev at the University of Copenhagen and his research team have analyzed environmental DNA (eDNA) from sediment cores taken at Lake Tjörnin, located in central Reykjavík. This site is recognized as one of Iceland’s oldest and most continuously occupied settlements. The goal was to identify species present during different historical periods.
By meticulously examining layers of volcanic ash, employing radiocarbon dating, and conducting plutonium isotope analysis, the researchers constructed a detailed timeline. This timeline spans from approximately 200 AD to the present day, correlating with known historical events.
A critical marker utilized in their study was the Landnám tephra layer, composed of ash and fragments from a volcanic eruption occurring around 877 AD. Most documented evidence of human activity in Iceland is found above this layer, indicating it was deposited after the eruption.
“Signs below the tephra are like the smoking gun that there was earlier human activity,” notes Chris Callow from the University of Birmingham, who was not involved in the research. This statement underscores the significance of finding evidence predating this well-established marker.
Indications of Early Biomass Burning and Sewage
Willerslev and his colleagues propose that human presence in Iceland began closer to 810 AD, approximately 70 years before the Landnám tephra. Their analysis revealed an increase in levoglucosan, a compound indicating biomass burning, alongside a rise in viruses associated with sewage, around this earlier period.
Callow commented on the implications, stating, “If it had been 850, I wouldn’t have been so surprised, but 810 is early for Viking expansion in the North Atlantic.” He added, “Overall, this is a nice confirmation of what we might have suspected, but it’s still quite controversial to have a date as early as 810.”
Kathryn Catlin of Jacksonville State University offers a more cautious perspective. While acknowledging the comprehensive environmental history constructed by the team as remarkable, she views the evidence for the 810 AD date as not entirely conclusive. Catlin questioned the scarcity of other human-related indicators: “When it comes to sewage biomarkers, there is a little bump around 800 and then nothing until 1900. Where are all the indicators of humans in sewage biomarkers and the intervening time period?” She also pointed out that while biomass burning can suggest human activity, fires can originate from natural causes, such as lightning strikes.
Shifting Perspectives on Environmental Impact
The research team also observed that the arrival of settlers coincided with an increase in local biodiversity. The eDNA data suggest that early inhabitants brought grazing livestock, cultivated hay, and practiced small-scale barley farming for brewing beer.
Contrary to the widely held notion of rapid deforestation, eDNA analysis of pollen indicated an expansion of birch and willow trees during the settlement period. For instance, birch pollen counts increased fivefold between 900 and 1200 AD. The researchers theorize this could be the result of deliberate land management, where livestock were kept away from trees to ensure continued access to wood for timber and fuel.
Catlin remarked on this finding, stating, “This is the nail in the coffin for that old just-so story of the Vikings getting to Iceland and then, suddenly, ‘oh no, the environment is destroyed’.” This suggests the environmental narrative of early settlement may require revision.
Significant numbers of domestic animals like sheep, cattle, pigs, and horses only appear in the eDNA record several decades after the initial settlement. The researchers propose this delay is because it would have taken approximately twenty years to establish herds large enough to be detectable in the eDNA. Callow, however, suggests an alternative explanation: the first arrivals might have brought fewer animals, potentially visiting primarily for the summer season to hunt walrus for ivory. “They could have been killing a few walruses and then going home again,” he posited.
Late Biodiversity Loss Linked to Climate and Natural Events
The eDNA also indicates that a substantial decline in biodiversity, including the loss of birch and willow trees, did not occur until after 1200 AD. The research team attributes this decline not to the presence of settlers but to a combination of factors, including climate cooling associated with the Little Ice Age (approximately 1250 to 1860 AD), volcanic eruptions, and storm surges.