Judy Skatssoon ABC Science Online. Aug 30, 2006
he Polynesians had trouble reaching remote South Pacific islands, according to a new study that dents their reputation as great seafarers.
An archaeological study shows they settled Rapa, an island southeast of Tahiti, more recently than anyone thought.
Professor Atholl Anderson, of the Australian National University (http://www.anu.edu.au/), and international colleagues publish their research in the current issue of the journal Antiquity (http://antiquity.ac.uk/).
Dating of charcoal from archaeological sites on the 20 square kilometre island suggests the first settlers arrived at Rapa as late as around 1200 AD, Anderson says.
The findings come after dates for the settlement of nearby Easter Island were recently revised to around the same time.
"What these pieces of archaeological research show is that the more isolated islands were reached very late in the history of the settlement of the Pacific, indicating that probably the seafaring technology was not as good as we once thought," Anderson says.
"The Polynesians were once regarded as almost superhuman seafarers who could go anywhere that they wanted. But now it doesn't look like that at all.
"It looks like they actually had great difficulty finding these remote and isolated places."
Anderson says the Polynesians are believed to have radiated out from islands like Fiji, Tonga and Samoa to more remote islands like Rapa after a 1500 year migratory lull, driven further afield by population pressure and food shortages.
After Rapa was settled, the population rapidly increased and spread across the island, Anderson says.
Archaeological analysis of swamps shows signs of rapid deforestation and erosion along the coast, suggesting the population was running out of land to plant taro crops.
The population apparently splintered into competing groups that set up formidable stone forts, consisting of a central tower surrounded by domestic terraces.
"It's always been a bit of a mystery as to why this very isolated island should have such a huge number of massive forts on it," Anderson says.
"The forts represent the time ... that it becomes a highly competitive society and ... they were simply fighting all the time."
Radiocarbon dating suggests they relocated from their coastal rock shelters to inland fortresses about 300 years after arriving and about 150 years before the first contact with Europeans in 1790.
The conclusions are based on 48 radiocarbon dates from a variety of sites, including five of the 16 known coastal shelters and four of the 15 fortifications.
The University of Oregon's Assistant Professor Douglas Kennett, who co-authored the paper, says Rapa tells a compelling story of population expansion, environmental degradation and increasing warfare.
"Rapa is a little microcosm of our planet. There are lessons about the consequences of population growth to be learned there," he says.
Anderson says time has recorded a classic pattern at Rapa.
"The argument is if any population is confined it overuses its resources [and] the result of that is almost always competition between units, groups, families, and ultimately war."