Africa, harboring the start of the migration, is at the top left and South America at the far right. Migration patterns are based on studies of mitochondrial (matrilinear) DNA. Dashed lines are hypothetical migrations.
The letters are the mitochondrial DNA haplogroups (pure motherly lineages); Haplogroups can be used to define genetic populations and are often geographically oriented. For example, the following are common divisions for mtDNA haplogroups:
The dashed path for X, stopping in Iceland, gestures at the "Solutrean hypothesis", an idea discussed in the popular media at the time the map was made but mostly discredited since.
