Wow, this is amazing timing. Today I just read a chapter in Guns, Germs, and Steel that talked about the expansion of humans to Australia and North America. Humans expanded out of Africa and into Asia by 1,000,000 BC. They reached the Pacific Islands by traveling by watercraft and expanding to any islands that were visible from from other islands. They were ahead of their time, in a way, when they invented watercraft; only 30,000 years later did watercraft come into use anywhere else in the world. They slowly expanded through indonesia. After a while, they eventually dicovered islands that were otherwise out of sight from any inhabited islands. At this time, New Guinea and Australia are connected by a land bridge (the ice age lowered sea levels). Once they discovered New Guinea, they were able to walk to Australia by 40,000 BC.