That runoff slowly robbed the settlers of valuable pastureland. To make matters worse, says Danish archaeologist Jette Arneborg, the Black Death had decimated Norway, wiping out nearly two thirds of the population. The plague hit Iceland, too, killing some 30 percent. Although there is still no evidence the sickness reached Greenland, archaeologists believe it left its mark by curtailing the flourishing trade. The Greenlanders adapted.
Recent evidence shows that their diet shifted from land-based foods to marine products.
The count reveals variations in the way forms of carbon are deposited and metabolized in food chains in the ocean and on land. Like their kin in Norway, the Vikings in Greenland had always exploited marine life but, by the close of the fourteenth century, the proportion of their food taken from the sea had risen to 80 percent. Between 1100 and 1200 A.D., as the colder weather arrived, so did the Thules. These Native Americans, migrants from the area surrounding the Bering Strait began trickling eastward from Ellesmere Island, just northwest of Greenland. Some researchers have speculated that Greenland Vikings may have met and intermingled with them, but researchers examining skulls found at Viking sites have found no traces of Native American morphology.