the similarity of their Austronesian languages, and the spread of a distinctive
type of pottery (Lapita ware), has shown that the Paci¿ c islands were settled
by people whose ancestors probably came from the mainland of Southeast
Asia. The islands of Melanesia (to the east of Papua New Guinea, reaching
as far as Fiji and Tonga) were settled over tens of thousands of years by
migrants traveling in huge, oceangoing double-hulled canoes, carrying taro,
yam, breadfruit, coconuts, and sugarcane as well as chickens, dogs, and pigs.
The remoter islands of eastern Polynesia were mostly settled during the 1st
millennium C.E. New Zealand, one of the last regions to be settled, was
probably colonized between 1000 and 1200 C.E.
How did the agricultural revolution play out in each of these zones? In the
Australasian zone, agriculture appeared early, but only in modern Papua New
Guinea. In Papua New Guinea, agriculture was based on root crops such
as taro that did not store well, which may be why no Agrarian civilizations
emerged here. However, there did emerge À ourishing and highly competitive
“early Agrarian” village communities, which have survived to the present
day. Agriculture À ourished because Papua New Guinea was at the leading
edge of the Australian tectonic plate as it plowed north so that, unlike other
parts of Australia, its landscapes were warped to form a great variety of
different soils and terrains. In Australia and Tasmania, landscapes were older
and À atter, and soils were poorer. Foraging technologies survived to modern
times. However, even in Australia there was signi¿ cant change within
recent millennia. Indeed, in some regions there appeared semi-sedentary
communities that are reminiscent of the afÀ uent Natu¿ an foragers of the
Fertile Crescent 12,000 years ago. By 500 years ago, when the world zones
would at last be joined, the population of Sahul cannot have been more than
about 2 million.
In the American zone, agriculture evolved later than in the Afro-Eurasian
zone, and in different ways. Though maize and squashes may have been
cultivated earlier, the earliest dated samples of domesticated maize were
grown about 3500 B.C.E., in the Tehuacán valley southeast of Mexico City.
In South America, guinea pigs, llamas, and alpacas were domesticated by
2000 B.C.E. The relatively late development of cultivation in the Americas
may reÀ ect the absence of “easy” domesticates. Crops such as maize had
to undergo signi¿ cant changes before they could support large populations,