What potential reason might there be for the prevalence of Neanderthal traits found so commonly amongst Australian Aboriginees? They often are found to have these distinguishing features that they share in common with Neanderthal man:

Recessed chins
Pronounced brow ridges
Occipital buns

However, as far as I know there was no Neanderthal man in Australia and the Aborigines were there fairly early, too. Could there have been fairly heavy interbreeding between the ancestors of the Aborigines and local Neanderthals when they passed through the Middle East c. 50,000 BC?