Severe drought in Western Polynesia - Samoa and Tonga - may have led to the settlement of the East Polynesian islands - such as the Cook Islands - earlier than previously thought.
A newly released anthropological study also suggested that settlement of East Polynesia, rather than being a rapid, wave-like event, was a much more incremental process, possibly extending over several generations.
One of those involved in the study, Auckland University archaeology professor, Melinda Allen, said the study appeared to show the people may been probing the margins of east Polynesia.
"...doing some exploration, perhaps leaving some pigs on an island, and coming back later," she said.
"So it just suggested a process of building up some knowledge about the islands and maritime environment."
Professor Allen said the currently accepted date for East Polynesian settlement was 1100AD to 1200AD, but this study showed it may have occurred up to 200 to 300 years earlier, from about 800AD to 1000AD.
Core samples were taken from Atiu in the Cook Islands Photo: Cook Islands Tourism
The study, led by Professor David Sear from the University of Southampton, took sediment cores from Lake Te Roto on Atiu in the Cook Islands.
This gave a sedimentary record, telling the story of the island's last 6000 years.
It included rainfall patterns, natural (pre-human) lake conditions and, in the uppermost layers, people's activities around this important water source.
Professor Allen said deteriorating climate conditions - a prolonged, severe drought - may have prompted their likely ancestors, in Tonga and Samoa, to resume long-distance voyaging and once again search for unsettled islands, like "the southern Cooks."
She said the information was based on three separate lake cores from Vanuatu, Samoa and the Cook Island.
"They are all registering this drought and suggesting it was quite extended - somewhere between one or two centuries. It is hard to know just how arid it was."
Professor Allen said she thought the new study was "pretty 'significant".
"We have got several different kinds of evidence we are using to put together this reconstruction.
"We have got a nice record there of human arrival, human impact on the environment and now we know why they may have have moved out of the western islands and into the eastern Pacific," she said
Professor Melinda Allen Photo: ResearchGate