Peopling of Sahul: mtDNA variation in aboriginal Australian and Papua New Guinean populations

Peopling of Sahul : mtDNA variation in aboriginal Australian and Papua New Guinean populations.
A J Redd and M Stoneking

We examined genetic affinities of Aboriginal Australian and New Guinean populations by using nucleotide variation in the two hypervariable segments of the mtDNA control region (CR). A total of 318 individuals from highland Papua New Guinea (PNG), coastal PNG, and Aboriginal Australian populations were typed with a panel of 29 sequence-specific oligonucleotide (SSO) probes. The SSO-probe panel included five new probes that were used to type an additional 1,037 individuals from several Asian populations. The SSO-type data guided the selection of 78 individuals from Australia and east Indonesia for CR sequencing. A gene tree of these CR sequences, combined with published sequences from worldwide populations, contains two previously identified highland PNG clusters that do not include any Aboriginal Australians; the highland PNG clusters have coalescent time estimates of approximately 80,000 and 122,000 years ago, suggesting ancient isolation and genetic drift. SSO-type data indicate that 84% of the sample of PNG highlander mtDNA belong to these two clusters. In contrast, the Aboriginal Australian sequences are intermingled throughout the tree and cluster with sequences from multiple populations. Phylogenetic and multidimensional-scaling analyses of CR sequences and SSO types split PNG highland and Aboriginal Australian populations and link Aboriginal Australian populations with populations from the subcontinent of India. These mtDNA results do not support a close relationship between Aboriginal Australian and PNG populations but instead suggest multiple migrations in the peopling of Sahul.

One of the other studies in this blog puts one of the M clades from SE Asia at about 87k old. The origin of Aborigines has been under debate for quite a while, with Southern India having some support as onepoint of immigration into Australia.along with PNG. This is going to be subject for a few posts. This stuff directly impacts on the OOA date, as genetic dating of Aborigines can set a lower limit to the migration date. 55k minimum for an entry into Northern Oz as a minimum now, so add about 15k for transit time and you are looking at about 70k absolute minimum (it’s probably a hell of a lot bit older). The changes in paleo-vegetation in Australia date it earlier, about 65k, so another 10k could be easily added to this.

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