Research upends the timing of Easter Island's societal collapse

Ahu Nau Nau site at Anakena beach on Easter Island

Samuel Clemens, aka Mark Twain, would smile at the conclusion of a new study led by University of Oregon doctoral candidate Robert DiNapoli. Easter Island’s prehistoric societal collapse did not occur as researchers have long thought.

DiNapoli’s team has developed a chronology of monument-building and reexamined written observations of early European visitors. With the help of statistics, the research clarifies variable radiocarbon dates pulled from soil under the island’s massive stone platforms topped with megalithic statues and large, cylindrical stone hats.

Like Twain’s famous quote, “The report of my death was an exaggeration,” the new findings indicate that descendants of Polynesian seafarers who settled Rapa Nui, aka Easter Island, in the 13th century continued to build, maintain and use the monuments for at least 150 years beyond 1600, the date long hailed as the start of societal decline.

“The general thinking has been that the society that Europeans saw when they first showed up was one that had collapsed,” said DiNapoli, who is completing doctoral work in the Department of Anthropology. “Our conclusion is that monument-building and investment were still important parts of their lives when these visitors arrived.”

DiNapoli worked with researchers from three other institutions on the study, which published online Feb. 6 in the Journal of Archaeological Science.

Easter Island, a Chilean territory, is 1,900 miles from South America and 1,250 miles from other inhabited islands.

By closely examining data from 11 of the sites, DiNapoli’s team connected radiocarbon dates from previous research to the order of assembly required to build the monuments. A central platform came first. Other sections — crematoriums, burial sites, plazas, statues and hats — were gradually added. Bayesian statistics were then used to refine the radiocarbon dates and estimate the timing of each these construction events.

Knowing the ordering of dates at a site can help refine radiocarbon dating, which often has a lot of uncertainty, such as large date ranges, DiNapoli said.

“Imagine building something with Lego bricks. You have to do it in a certain order, building over time,” he said. “These monuments also have a necessary order of assembly, and radiocarbon dates from earlier building stages must come before later ones. This information is useful because it allows us to deal with the variability in radiocarbon dates that came from the excavation in a more precise way.”

Monument building, he said, began soon after settlement and increased rapidly, with a steady period of construction continuing beyond the hypothesized collapse and European arrival.

Dutch travelers in 1722 noted the monuments were in use for rituals and showed no evidence for societal decay. The same was reported in 1770, when Spanish seafarers landed. However, when British explorer James Cook arrived in 1774, he and his crew described an island in crisis, with overturned monuments.

“Once Europeans arrive on the island, there are many documented tragic events due to disease, murder, slave raiding and other conflicts,” said co-author Carl Lipo, an anthropologist at Binghamton University. “These events are entirely extrinsic to the islanders and have, undoubtedly, devastating effects. Yet, the Rapa Nui people — following practices that provided them great stability and success over hundreds of years — continue their traditions in the face of tremendous odds.”

The approach developed for the research, which was funded by the National Science Foundation, may be useful for testing hypotheses of societal collapse at other sites around the world where similar debates on timing exist, the researchers noted.

DiNapoli has been to Rapa Nui several times as a graduate student.

“I’ve wanted to be an archaeologist since I was a little kid,” he said. “Rapa Nui was a place I was always interested in. It’s this amazing mystery, of these people who live on a small, isolated island. As an undergraduate archaeology student at UCLA, I knew that I was interested in Pacific Island archaeology.”

DiNapoli began his Rapa Nui journey as a master’s degree student at the University of Hawaii under co-author Terry Hunt, who he followed to the UO for doctoral work after Hunt joined the UO in 2013. Hunt became the dean of the University of Arizona’s Honors College in 2017.

The study’s fourth co-author was Timothy M. Rieth of the International Archaeological Research Institute in Hawaii.

—By Jim Barlow, University Communications