New genetic studies of Autralian and New Guinean natives appear to confirm the two populations come from the same genetic heritage. Differences between them appear to be the result of divergent mutations caused by their respectively isolated populations and not secondary migrations,or interbreeding with other populations like homo erectus. This evidence supports the evolution "Out of Africa" theory of human evolution that holds that all humans share a common ancestry. The aboriginal populations of New Guinea and Australia, which migrated to these areas arounf 50,000 years ago, have been the primary evidence utilized by critics of this theory.
"Until now, one of the main reasons for doubting the “Out Of Africa” theory was the existence of inconsistent evidence in Australia. The skeletal and tool remains that have been found there are strikingly different from those elsewhere on the “coastal expressway” – the route through South Asia taken by the early settlers. Some scholars argue that these discrepancies exist either because the early colonists interbred with the local Homo erectus population, or because there was a subsequent, secondary migration from Africa. Both explanations would undermine the theory of a single, common origin for modern-day humans. But in the latest research there was no evidence of a genetic inheritance from Homo erectus, indicating that the settlers did not mix and that these people therefore share the same direct ancestry as the other Eurasian peoples."