Berkeley -- A new history of the Pacific islands before their discovery by European voyagers buries forever the myth that Tahitians and other peoples of Oceania were children of nature living in the Garden of Eden.

In the first major synthesis of Pacific prehistory in 20 years, an anthropologist at the University of California, Berkeley, shows that, before Magellan ever set sail in the Pacific, human settlement and, in some cases, overpopulation on many Pacific islands disrupted the ecological chain, sending some island societies into collapse.

"French philosophers of the Enlightenment saw these islands, especially Tahiti, as the original natural society where people lived in a state of innocence and food fell from the trees. How wrong they were," said Patrick Kirch, professor of anthropology and director of UC Berkeley's Phoebe Hearst Museum of Anthropology.

"Most islands of the Pacific were densely populated by the time of European contact, and the human impact on the natural ecosystem was often disastrous - with wholesale decimation of species and loss of vast tracts of indigenous forest."

Moreover, he pointed out, Tahitian society was engaged in endemic warfare, with ritual human sacrifice to a blood-thirsty god named Oro, when French explorer Louis de Bougainville came for a two-week trip in 1769 and thought he had arrived in paradise. Bougainville's description of Tahiti became the basis for Jean Jacques Rousseau's concept of l'homme naturel, the nobel savage.

Kirch's synthesis brings together archaeology, linguistics, biology and oral tradition to reach broad new insights about cultures than spanned 5,000 miles of ocean. "On the Road of the Winds: An Archaeological History of the Pacific Islands before European Contact," published this month, covers 40,000 years, from the first movement of Southeast Asian people into the Pacific to the consolidation of the Hawaiian Islands under King Kamehameha in the 18th century.

Kirch emphasized, however, that Pacific island peoples were no worse and no better than any other human beings. "All humans transform their environment. In the Pacific, there is no place that humans haven't modified," he said.

Kirch's recent research on islands from New Guinea to Hawaii establishes that settlement of the Pacific was one of the fastest human expansions of all time.

In two great leaps - the Lapita expansion around 1,500 B.C. to 1000 B.C. and the ancient Polynesian expansion about 1,000 years later - agricultural voyagers settled the Pacific islands in great sweeps outward from an original base, probably in Taiwan.

They carried with them a Noah's ark full of domesticated plants and animals - the coconut tree (found wild in only a few places), taro and other crop plants, chickens, pigs, dogs, and a mouse-sized rodent called the Pacific rat.

"They took their whole world with them," said Kirch. "It was an amazing expansion, one of the most rapid expansions in world history prior to European colonization."

The early Lapita expansion, from the Bismarck Archipelago near New Guinea to Samoa in the central South Pacific, was so fast it looks to the archaeological eye as if it happened instantly, said Kirch. Radiocarbon dates for settlement of different islands fall within the error range, which is about 300 years, for that technique.

By careful analysis, Kirch was able to tease out a small difference in settlement dates. He concludes that the Lapita culture, an antecedent of Polynesian society, settled numerous islands across 2,500 miles in about 250 to 300 years.

The later Polynesian expansion, from Samoa to Hawaii and Easter Island, occurred nearly as fast across much longer stretches of open ocean, said Kirch.

This movement could not have been driven by population pressures in such a short time, he said. Very likely, it was driven by the custom of primogeniture, the exclusive right of the eldest son to inherit all wealth and property.

"Junior sons seek out new lands where they can found their own house and lineage," said Kirch. He added that rivalry between older and younger brothers is a frequent theme in Polynesian mythology.

Linguistic evidence also backs up this theory. Construction of a Proto-Oceanic language from existing languages shows that in the ancient Lapita society, siblings were ranked and property passed to the first-born offspring.

New sailing technology also aided the expansion, said Kirch. Polynesians invented the catamaran, a two-hulled, two-masted ship capable of carrying up to 80 people plus plants and animals, before they undertook the voyage of 2,500 miles across open ocean from the Marquesan Islands to Hawaii at about 400-700 A.D.

In bringing together evidence from all of the subdisciplines of anthropology, Kirch has been able to reach new conclusions about the Pacific past, especially the impact of human settlement on the natural biota.

He shows in vivid detail the social and ecological collapse of Easter Island and Mangaia, plagued by overpopulation and depletion of resources. People took to living in subterranean caverns for protection from social terrorism, while the monumental statues on Easter Island are mute testimony to intergroup rivalry.

On Mangaia, a rock shelter was discovered filled with nothing but charred human bones and ovens. By contrast, the tiny island of Tikopia in the Solomon Islands created a marvel of sustainable agriculture on 4.6 square miles and for centuries maintained a large-for-its-size population of up to 1,700 people.

Tikopians, like the people of Mangaia and Easter Island, originally burned forests for crop planting. But around 900 A.D., they radically altered course, creating multistory orchard stands of fruits and nuts, among other ecologically-wise decisions, said Kirch.

They also believed strongly in zero population growth and used drastic means, including infanticide, to achieve it. The result, said Kirch, was a stable social system and a model of agriculture that "is perhaps unparalleled anywhere in the Pacific."

"This island experience poses critical lessons for the modern world," he said. "These two outcomes - one disastrous, one successful -teach us that we have choices. Nothing is inevitable or predetermined about the consequences of human impact on the earth we have inherited.

"These island environments are laboratories to show us how to achieve a sustainable relationship with our planet on a global basis."