The Spread Of People To Australia
Archaeological evidence shows that modern humans had reached South-east Asia by 70,000 years ago.
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The ‘Multiregional’ Model
Some scientists interpret the variation found in the fossil record of early Indigenous Australians as evidence that Australia was colonised by two separate genetic lineages of modern humans. One lineage was believed to have been the evolutionary descendants of Indonesian Homo erectus while the other lineage had evolved from Chinese Homo erectus. Modern Aboriginal people are the result of the assimilation of these two genetic lineages.
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I suppose that’s just a fancy way of saying that they came from the regions most accessible during the period that the sea levels were lower and the numerous islands of what we know as Indonesia, the Phillipines and the Malay Archipelago had footpaths...to Australia