New Research Challenges Story of Collapse on Easter Island

Monumental statues on Easter Island.

Monumental statues on Easter Island. Arian Zwegers via Flickr

A new study casts doubt on the narrative often told about Easter Island, of an ancient society that plundered its forests to the point of collapse. Researchers have found fresh evidence for another, more hopeful story — that the islanders learned to live within the bounds set by nature.

When Europeans first arrived to the remote South Pacific island in 1722, they found hundreds of massive statues, evidence of considerable manpower, but only around 3,000 people, too few to easily explain the monuments. Historians inferred that the Polynesians who settled Easter Island must have seen their population grow to a large and unsustainable level, at which point they destroyed their forests, exhausted their soils, and hunted seabirds to oblivion before seeing their own numbers collapse.

But in recent years a competing narrative has taken hold. It posits that the population never exploded, but that instead a small number of people learned to sustain themselves on the arid and relatively barren island. Researchers found evidence for this view in the remains of “rock gardens,” where islanders grew sweet potatoes, their staple crop.

An Easter Island rock garden.

An Easter Island rock garden. Carl Lipo

To protect crops from sea winds and supply minerals to the soil, islanders grew potatoes among densely packed rocks. It has been difficult to determine, however, how much of the island was comprised of rock gardens, which would indicate how many people farming sustained. Prior research found that rock gardens potentially covered more than 12 percent of Easter Island, which, scientists estimate, could have supported as many as 25,000 people.

For the new study, researchers aimed to improve on previous inventories of rock gardens by studying gardens on the ground and then training artificial intelligence to identify them in satellite imagery. To better distinguish between rock gardens and rocky outcroppings, they also gathered satellite data on the levels of moisture and nitrogen in the soil, markers of cultivation.

With this additional data, researchers determined that rock gardens covered less that 0.5 percent of the island. Accounting for other potential sources of food, such as fish, bananas, taro, and sugar cane, they estimated that Easter Island would have supported around 3,000 people, the number first recorded by Europeans. The findings were published in Science Advances.

“The population could never have been as big as some of the previous estimates,” said lead author Dylan Davis, a postdoctoral researcher at Columbia University. “The lesson is the opposite of the collapse theory. People were able to be very resilient in the face of limited resources by modifying the environment in a way that helped.”

History will show that the islanders did ultimately face collapse, but after Europeans arrived. Traders brought smallpox and enslaved as many as half of the native people. By 1877, there were just 111 left.


Climate Clues from the Past Prompt a New Look at History