Tucson Standard

Some 800 years ago, a small band of Polynesians sailed across the Pacific to settle Rapa Nui, also known as Easter Island. There, they erected hundreds of "moai," or gigantic stone statues that now stand as emblems of a vanished civilization. The longstanding narrative has been that their numbers grew unsustainably, leading to environmental collapse and population decline by the time Europeans arrived in 1722.

A new study challenges this narrative, suggesting that Rapa Nui's population remained stable and sustainable for centuries. Researchers presented evidence from sophisticated inventories of "rock gardens" where islanders cultivated sweet potatoes. The study was published in the journal Science Advances.

Terry Hunt, a professor at the University of Arizona and co-author of the study, stated, "Our more than 20 years of archaeological field research on Rapa Nui continues to challenge long-held assumptions about the island's past." He added that ancient islanders found ingenious solutions to adapt sustainably.

Dylan Davis, lead author and postdoctoral researcher at Columbia Climate School, noted, "This shows that the population could never have been as big as some previous estimates. People were able to be very resilient in the face of limited resources."

Easter Island is one of the most remote inhabited places on Earth. To cope with its challenging environment, settlers used rock gardening or lithic mulching. This technique involved scattering rocks over low-lying surfaces and planting crops like sweet potatoes between them. The rocks helped manage soil nutrients and temperature fluctuations.

Hunt explained that rock mulch solved issues related to nutrient-poor soils and strong winds: "The use of rock mulch created sustainable agriculture for a relatively small population."

Despite earlier estimates suggesting much larger populations based on moai construction efforts, recent surveys using machine-learning models indicated that rock gardens occupied only about 188 acres—less than half a percent of the island. These findings support a stable population size around 3,000 people at European contact.

Carl Lipo from Binghamton University highlighted ongoing misconceptions: "People's lifestyle must have been incredibly laborious... Think about sitting around breaking up rocks all day." He emphasized accumulating evidence against large historical populations.

Today, Rapa Nui's population is nearly 8,000 with an additional influx of tourists annually. While some residents still use ancient gardening techniques revived during pandemic lockdowns when imports were restricted, modern farming practices may not be sustainable due to soil depletion risks.

The new study marks another milestone for UArizona professor Hunt in his decades-long research on Rapa Nui. Past studies by Hunt have explored various aspects such as statue transportation methods and disproving theories about crop decimation for moai construction.

Additional co-authors include Robert DiNapoli from Binghamton University and Gina Pakarati from Rapa Nui.

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