Whole-genome genetic diversity in a sample of Australians with deep Aboriginal ancestry

Australia was probably settled soon after modern humans left Africa, but details of this ancient migration are not well understood. Debate centers on whether the Pleistocene Sahul continent (composed of New Guinea, Australia, and Tasmania) was first settled by a single wave followed by regional divergence into Aboriginal Australian and New Guinean populations (common origin) or whether different parts of the continent were initially populated independently. Australia has been the subject of relatively few DNA studies even though understanding regional variation in genomic structure and diversity will be important if disease-association mapping methods are to be successfully evaluated and applied across populations. We report on a genome-wide investigation of Australian Aboriginal SNP diversity in a sample of participants from the Riverine region. The phylogenetic relationship of these Aboriginal Australians to a range of other global populations demonstrates a deep common origin with Papuan New Guineans and Melanesians, with little evidence of substantial later migration until the very recent arrival of European colonists. The study provides valuable and robust insights into an early and important phase of human colonization of the globe. A broader survey of Australia, including diverse geographic sample populations, will be required to fully appreciate the continent's unique population history and consequent genetic heritage, as well as the importance of both to the understanding of health issues.

Modern human origins in Australasia: Testing the predictions of competing models

The evolutionary background to the emergence of modern humans remains controversial. Four models have been proposed to explain this process and each has clearly definable and testable predictions about the geographical origins of early Australians and their possible biological interaction with other Pleistocene populations. The present study considers the phenetic affinities of early Australians from Kow Swamp (KS 1 and KS 5) and Keilor to Pleistocene Africans and Asians from calvarial dimensions. The study includes analyses employing log-transformed and size-corrected (Mosimann variables) data. The strongest signals to emerge are as follows: (1) a phenetic pattern in which Australians are most like each other, (2) all three crania possess a mosaic of archaic and modern features, (3) Kow Swamp crania also show strong affinities to archaic remains, (4) Keilor is more modern than KS 1 and KS 5 and (5) Keilor shows affinities to Pleistocene East Asian modern crania (Liujiang and Upper Cave 101) providing evidence for a broad regional morphology. The results refute the predictions of multi-species replacement models for early Australians but are consistent with single-species models. Combined with published evidence from DNA, the present study indicates that the Assimilation model presently offers the best explanation for the origins of Pleistocene Australians.