Thaks for the explanation-- but now I am a bit confused. If humans were in Oz by 50,000 years ago how did they get there given that there is an objection to Melanesians inhabiting their area before 30,000 years ago because of "boating technology" not being advanced enough. Given that there is a visual resemblance to the (extinct?) Hoabinhian culture of SE Asia would it be reasonable to assume that the original inhabitants of Oz got here via a land bridge? If so, I thought that this theory had been discredited. How else do you suppose they may have reached Australia though? However it would, as you point out, explain the possibility of 2 waves of people.