Comparing the World Zones ...........................................................

LECTURE

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 À at 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
À ora and fauna. No other large mammal made this crossing, so it provides
clear evidence of our ancestors’ unique ecological adaptability. Megafaunal