Ancient Polynesian builders rapidly evolved from small temples to big pyramid-shaped temples in only 140 years, rather than four or five centuries as previously believed, a team led by Hawaii-born anthropologist Patrick V. Kirch has found.

The anthropologists studied 22 temple sites made of coral on the island of Moorea, using a high-precision thorium/uranium process to date decorative veneers, large blocks and religious offerings.

Kirch, a University of California, Berkeley, anthropologist, said in a telephone interview that he first used the coral dating technique in a Kahikinui, Maui, archaeological project that began in 1994.

The early settlers there did not use coral as building blocks, but put a piece of branch coral on altars of offerings when they dedicated heiau and sometimes put them in walls, he said.

He said his team dated coral pieces on platforms at Kahikinui and got a tight date range around the end of the 16th century and beginning of the 17th century.

"They built temples larger and larger before Capt. Cook arrived," said Kirch, who was with the Bishop Museum’s anthropology department from 1975 to 1984. "The beauty of dating coral is it’s so precise, compared to radiocarbon dating. It’s really a breakthrough."

The best dates obtained with the radiocarbon method are plus or minus 45 or 50 years, while coral dates are plus or minus four or five years, he said.

The temples, or "marae," in the Society Islands are perfect for the technique because blocks of coral were used for construction, he said. Since coral used in temple construction was collected while it was alive and used quickly, he said, the date of final growth of the coral specimens provides the temple construction date.

The team, which included anthropologist Jennifer G. Kahn of the Bishop Museum, recently reported its findings in the print edition of the journal Proceedings of the National Academy of Sciences. The National Science Foundation funded the project.

The researchers said they found "a clear progression of architectural change and increasingly elaborate temples on Moorea from 1620 to 1760 A.D.," which they connected to political competition. Cook arrived in 1769.

"The construction of these massive temples, with their ahu (altar platforms) reaching ever higher toward the heavens, was clearly an important part of the strategy of chiefly elite to gain favor with the gods and to assert their power and prestige over their people," the researchers wrote.

They believe there was political competition between the chiefs of Tahiti and Moorea.

He said the largest temple built on Tahiti had 11 terraces and a big pyramid altar that was destroyed by missionaries. The ones on Moorea survived, he said, describing the largest as almost 350 feet long with stepped altars and four or five terraces.

"They’re massive constructions," he said, with coral blocks 3 to 4 feet long.

Kirch co-directed the Moorea fieldwork in 2007 with Warren Sharp of the nonprofit Berkeley Geochronology Center.

The researchers note in their paper that development of ritual architecture in Mexico’s Oaxaca Valley is estimated to have taken more than 1,300 years, while the temple development on Moorea occurred rapidly within 140 years, according to the coral dates.

Kirch, author of "On the Road of the Winds: An Archaeological History of the Pacific Islands Before European Contact," said the first settlement dates for the Society, Marquesan and Hawaiian islands are still being debated. He said the researchers may be able resolve the controversy by dating coral used by ancient Polynesians to make fishhooks.