"I have heard it said of the Australian Aborigines that their contribution to Australia is that after 10,000 years of living there, they left the land just as they found it. (No small achievement)"

Sorry to say, the statement is completely idiotic.

As soon as the Australian aborigines figured out how to start a fire, they burned entire forests, then walked into the smouldering mess and carried off dying roos and anything else the wanted to eat.

Estimates are the 70% of Australia was torched at least one in the last few hundred of years. As much as 30% was probably torched yearly.

As sombody pointed out, the damage native peoples did (and still do) was limited by their means, not noble intent.