Hawaiian genealogies and oral histories hold that sometime around 1600 A.D. a ruler named Pi'ilani united two opposing chiefdoms on Maui into a peaceful kingdom, marking the emergence of a religious state on the island. Archaeologists had been unable to confirm that sequence of events, however, in part because of the limitations of carbon dating.
In the new work, Patrick V. Kirch and Warren D. Sharp of the University of California and Berkeley used another kind of radiometric technique involving thorium-230, rather than carbon-14, to date bits of branch coral that were collected from living reefs and left as divine offerings at seven different temples during construction. Dates for these corals, which had been incorporated into walls and platform fill, all fell in a narrow range of 1565 to 1638 A.D., give or take a few years on either end. Moreover, dates on the samples that best reflect the time they were harvested from the sea--those from the coral branch tips--ranged from 1608 to 1638 A.D., an interval of just 30 years. These findings thus point to intensive temple-building during that time. Because temples served as centers for control of production and the collection of surplus goods, the team contends, it seems likely that the construction boom accompanied a profound shift in sociopolitical structure.
Kirch and Sharp observe that the conquests described by local oral traditions coincide with these new dates, and would have more than doubled the size of the Maui polity to upwards of 2,360 square kilometers--the magnitude of expansion expected with the formation of an archaic state. "The temples provide tangible archaeological evidence of the speed with which a fundamental sociopolitical transition occurred in proto-historic Hawaii," the authors conclude. Indeed, they note, it may have happened in the span of a single generation of Hawaiians.