The study offers some insight into the evolution of modern human populations in small geographic areas as well as their initial spread throughout the world. For instance, the researchers were able to tease apart the genetic ancestries of eight different European groups and four groups in the Middle East. Their data set also supports an “out of Africa” model for the spread of the first modern humans, who colonized the rest of the world in stepping-stone fashion after leaving Africa. Genetic variation within populations accounts for most of human genetic diversity, the researchers confirm, but they also suggest that there is enough between-population variation to delineate and compare human populations on a fine scale.