The New York Times reports on research by Decode that has resulted in the sequencing of the genomes of 2,636 Icelanders, the largest collection ever analyzed in a single human population. Because of the completeness of Iceland‘s genealogical records, Decode‘s scientists were able to do something rather remarkable: work out the full genomes of another 100,000 Icelanders, a third of the entire country, without collecting any of their DNA.