The Greenland Norse colonized North America 500 years before Christopher Columbus "discovered" it, establishing farms in the sheltered fjords of southern Greenland, exploring Labrador and the Canadian Arctic, and setting up a short-lived outpost in Newfoundland.
But by 1450, they were gone, posing one of history's most intriguing mysteries: What happened to the Greenland Norse?
There are many theories: They were starved off by a cooling climate, wiped out by pirates or Inuit hunters, or perhaps blended into Inuit society as their own came unglued.
Now scientists are pretty sure they have the answer: They simply up and left.
"When the climate deteriorated, and their way of life became more difficult, they did what people have done throughout the ages: They looked for a more opportune place to live," says Niels Lynnerup, a forensic anthropologist at the University of Copenhagen in Denmark who studies the Norse.
I didn't think there were any real competing hypotheses.