In order to substantiate the southern route hypothesis of the settlement of Australia, a link between Australia and coastal populations of Asia is needed. Australian mtDNA belongs largely to the same Out-of-Africa subclades M and N, but it is not clearly a branch of a more derived clade that would allow us to pinpoint a specific Eurasian location as a place of origin.
This paper makes the case that Australian mtDNA haplogroup M42 shares two polymorphisms with a set of Indian M sequences, suggesting more recent common ancestry between these Indians and Australians than the generic "Out of Africa" M. The simplest explanation for this is that the M42 ancestors of Australians ultimately originated in India, and were thus part of the "southern route" dispersal of humans from Africa.
BMC Evolutionary Biology 2009, 9:173doi:10.1186/1471-2148-9-173
Reconstructing Indian-Australian phylogenetic link.
Satish Kumar et al.
An early dispersal of biologically and behaviorally modern humans from their African origins to Australia, by at least 45 thousand years via southern Asia has been suggested by studies based on morphology, archaeology and genetics. However, mtDNA lineages sampled so far from south Asia, eastern Asia and Australasia show non-overlapping distributions of haplogroups within pan Eurasian M and N macrohaplogroups. Likewise, support from the archaeology is still ambiguous.
In our completely sequenced 966-mitochondrial genomes from 26 relic tribes of India, we have identified seven genomes, which share two synonymous polymorphisms with the M42 haplogroup, which is specific to Australian Aborigines.
Our results showing a shared mtDNA lineage between Indians and Australian Aborigines provides direct genetic evidence of an early colonization of Australia through south Asia, following the "southern route".