Of all species on the face of the earth, humans are the most disperse, in that they occupy the most diverse eco-systems present on all large land masses and most large islands.
In recent time, much work has been done using maternally inherited mitochondrial DNA, and non-recombinant Y (NRY) chromosome markers to map human migration and ancestry. In addition, large numbers of other DNA based markers have been used for similar purposes. However, anthropological geneticists have been looking at human migration and ancestry for as long as there have been genetic markers, starting with the ABO blood groups.