Through most of Eurasia, societies became progressively less isolated over time. But in 1400 there still remained many isolated societies, especially in the islands east of modern Indonesia. As discussed in Chapter 1, Homo sapiens began settling the western Pacific islands very early, reaching Australia by 50,000 years ago and New Guinea by 35,000 years ago. The process did not stop there, however. The ancient Austronesians (speakers of Austronesian languages) were skilled mariners who settled numerous islands of the Pacific in subsequent centuries, generally following the coasts. Their descendants, the Polynesians, learned how to sail into the open ocean with only the stars, currents, wind patterns, paths of birds, and perhaps paths of whales and dolphins to help them navigate. They reached Tahiti and the Marquesas Islands in the central Pacific by about 200 C.E.

After reaching the central Pacific, Polynesians continued to fan out, in some cases traveling a thousand or more miles away. They reached the Hawaiian Islands in about 300 C.E., Easter Island in perhaps 1000, and New Zealand not until about 1000–1300. There even were groups who sailed west, eventually settling in Madagascar between 200 and 500.

In the more remote islands, such as Hawai‘i, Easter Island, and New Zealand, the societies that developed were limited by the small range of domesticated plants and animals that the settlers brought with them and those that were indigenous to the place. Easter Island is perhaps the most extreme case. Only 15 miles wide at its widest point (only 63 square miles in total area), it is 1,300 miles from the nearest inhabited island (Pitcairn) and 2,240 miles from the coast of South America. At some point there was communication with South America, as sweet potatoes originally from there made their way to Easter Island. The community that developed on the island raised chickens and cultivated sweet potatoes, taro, and sugarcane. The population is thought to have reached about fifteen thousand at Easter Island’s most prosperous period, which began about 1200 C.E. It was then that its people devoted remarkable efforts to fashioning and erecting the large stone statues that still dot the island.

What led the residents of such a small island to erect more than eight hundred statues, most weighing around ten tons and standing twenty to seventy feet tall? One common theory is that they were central to the islanders’ religion and that rival clans competed with each other to erect the most impressive statues. The effort they had to expend to carve them with stone tools, move them to the chosen site, and erect them would have been formidable.

After its heyday, Easter Island suffered severe environmental stress with the decline of its forests. The islanders could not make boats to fish in the ocean, and bird colonies shrank as nesting areas decreased, also reducing the food supply. Scholars still disagree on how much weight to give the many different elements that contributed to the decline in the prosperity of Easter Island from the age when the statues were erected.

Certainly, early settlers of an island could have a drastic impact on its ecology. When Polynesians first reached New Zealand, they found large birds up to ten feet tall. They hunted them so eagerly that within a century the birds had all but disappeared. Hunting seals and sea lions also led to their rapid depletion. But the islands of New Zealand were much larger than Easter Island, and in time the Maori (the indigenous people of New Zealand) found more sustainable ways to feed themselves, depending more and more on agriculture.