The remains of small sea creatures are providing fresh insights into one of the most important periods in the history of pre-contact Hawaii, archaeologists say.

A new study of indigenous temples, or heiau, on the island of Maui has set out to identify when the island’s native population — initially spread out over several small chiefdoms — first came together under a single ruler.

The island’s sacred sites range from small shrines dedicated to deities of fishing and agriculture, to “monumental” temples whose foundations are still identifiable today, said Dr. Patrick Kirch of the University of California at Berkeley.

“[Maui] is one of the few places in the Hawaiian islands where the archaeological landscape of an entire ancient district is still intact, not disturbed either by plantation agriculture or modern tourism or housing developments,” Kirch said.

“Heiau vary tremendously in size and form; there were different kinds of heiau for different gods,” he explained.

“When in use, they had thatched buildings to hold temple paraphernalia, wooden images, wooden oracle towers, et cetera, but all of those perishable superstructures are now gone.

“What we see as archaeologists are the stone foundations — generally platforms or terraces, or sometimes walled enclosures.” [See another find recently made in the islands: “Monster Surf Exposes Rare Petroglyphs in Hawaii“]

And with his colleagues, Kirch has been investigating these sites in search of a unique and durable artifact: pieces of a small, stony coral known as Pocillopora meandrina.

“The coral branches were placed as offerings on altars, and sometimes incorporated into the stone walls during construction,” Kirch explained.

“We do not know the exact ideology behind this, but there are hints in Hawaiian traditions that the corals may have represented the god Kane — the god of flowing waters, irrigation, and the taro plant — or possibly the god Lono, the god of dryland farming and the sweet potato.”

While their precise purpose remains unclear, the corals are nonetheless useful, because they can be scientifically dated. So although the heiau’s original structures have vanished, archaeologists can study the corals left there to determine when they were constructed and used.

And this can be a crucial clue in tracing the island’s political development, Kirch said.

Signs of a temple-building boom would likely indicate a period of political consolidation, as ancient Hawaiian rulers often ramped up their religious authority in order to also wield economic and political authority.

Often, this involved building shrines and temples near farmlands and other areas of food production. This strengthened the symbolic association between rulers and the gods who controlled nature’s bounty, and also made it easier for leaders to reap tributes from local growers.

“The Hawaiian polities were fundamentally based on agricultural production,” Kirch explained.

“The chiefs and kings extracted surplus production from the commoners and used this to underwrite their own interests, such as supporting craft specialists and warriors.”

But previous studies of this part of Maui have reached differing conclusions about when exactly its temple construction — and therefore its political consolidation — took place.

One study of charcoal from the heiau, for example, used radiocarbon dating to conclude that most of the temples were built between the years 1400 and 1650, a period that’s at least a century earlier and longer than traditional accounts of when Maui’s first island-wide kingdom was established.

But Kirch and his colleagues dated the sites using a different technique. Instead of analyzing carbon, they studied the corals’ levels of uranium, which decays into the element thorium at predictable rates.

Their analysis of 46 coral samples from 26 of the temple sites suggests that most of the heiau were built more recently and more rapidly, over a span of no more than 150 years, ending around the year 1700.

“First of all, the new dates are important just because of their high precision,” Kirch said.

“In the past we have had to use radiocarbon dating, which has much wider error ranges and calibration issues.

“With the uranium/thorium coral dating we are getting error ranges of about 2 to 10 years at two standard deviations. This is a huge advance in chronological precision.

“Second, the new results confirm … that the Maui temples were constructed in a relatively short period of time, with a duration of about 150 years at maximum, between circa 1550 to 1700.

“This is the same time during which the Hawaiian oral traditions indicate that Maui island was consolidated into a single kingdom, under the reigns of King Pi’ilani and his successors Kiha-a-Pi’ilani and Kamalalawalu.” [Learn about a discovery from another pivotal period: “1,500-Year-Old Village, A Sign of ‘Revolution’ in the Southwest, Excavated in Colorado”

What’s more, the team’s results suggest that a peak of temple construction occurred between about 1572 and 1603, when eight temples were built farther inland.

This is consistent with the known settlement patterns of the region, Kirch noted, when most people lived and farmed in the uplands, where there was enough rainfall to grow sweet potatoes and taro.

“Many of the temples in the upland zone seem to be associated with the two main gods of agriculture: Kane and Lono,” Kirch said.

Building monuments to these gods in these agricultural areas likely sent a clear message from King Pi’ilani and his successors to the people of Maui, Kirch said.

“We conclude that rapid temple construction was part of the overall political strategy used by these rulers to consolidate power, control agricultural production, and extract surplus,” he said.

Reporting their findings in the Journal of Archaeological Science, Kirch and his colleagues write that their study “underscores the importance of monumental ritual architecture in the emergence of archaic states in ancient Hawai’i.”

Kirch, P., Mertz-Kraus, R., & Sharp, W. (2015). Precise chronology of Polynesian temple construction and use for southeastern Maui, Hawaiian Islands determined by 230Th dating of corals Journal of Archaeological Science, 53, 166-177 DOI: 10.1016/j.jas.2014.09.025