Comparing the World Zones Lecture 36
The ice age continent of Sahul included modern Australia, Papua New Guinea, and Tasmania. It was uni¿ed because lower sea levels at the height of the last ice age ¿lled the bridges between these areas—so, it was a single landmass.
H
ow typical was Afro-Eurasia of the sort of historical changes that occurred in other parts of the world? To answer this question, the next two lectures survey developments in the American, Australasian, and Paci¿c world zones. At ¿rst sight, what stand out are the huge differences between these different worlds. But as we look more carefully, we will also begin to see some surprising and important similarities. Comparisons between world zones are important for two main reasons. First, the differences mattered. They shaped the diverse histories of each region; but they also shaped the history of the world as a whole in the last 500 years, since the coming together of the world zones. Second, if we ¿nd important similarities between the zones despite the lack of signi¿cant contact between them, this may hint at some deep patterns in human history as a whole. Here, I will summarize information on the early history of the various world zones. During the ice ages, modern Australia, Papua New Guinea, and Tasmania were united within the continent of Sahul. The Australasian zone was smaller in area than the Afro-Eurasian or American zones, and less diverse, with relatively arid climates and Àat landscapes (except in modern Papua New Guinea). Its soils were old and relatively infertile. Sahul inherited the marsupial fauna of the supercontinent of Gondwanaland, of which it was a fragment, but it had separated from Gondwanaland almost 100 million years ago, so its plant life and animal life were quite distinctive. The human history of Sahul began 40,000 to 50,000 years ago, during the last ice, when it still formed a single continent. To reach Sahul from Outer Eurasia, humans had to cross at least 60 kilometers of open sea and adapt to entirely new Àora and fauna. No other large mammal made this crossing, so it provides clear evidence of our ancestors’ unique ecological adaptability. Megafaunal 165
