A recent study finds that the rock gardens of Easter Island challenge the traditional 'ecocide' theory about the collapse of its civilization.

When British explorer James Cook visited Rapa Nui, or Easter Island, in 1774, he observed small groups of malnourished inhabitants struggling to survive on a barren, treeless landmass in the Pacific. 'Nature has been exceedingly sparing of her favours to this spot,' he noted. However, Cook had come to acquire supplies and to see the famed moai stone statues with oversized heads, marvels noted by earlier European expeditions.

Rapa Nui posed an archeological puzzle: The moai statues, towering up to 33 feet tall and weighing around 14 tons each, were transported across the island for display. How could a people on such a remote, harsh island, struggling for survival, create over 900 of these statues? The challenge seemed nearly impossible, considering the island’s isolation, being 2300 kilometers from the nearest continent and lacking global technological advances.

Some scholars have proposed an 'ecocide' narrative: Before European contact, Rapa Nui's once-thriving civilization allegedly depleted the island’s finite natural resources—such as the trees—to sustain the effort of building the moai. This resource depletion, scholars argue, contributed to a societal collapse that left the island depopulated long before the devastating impact of European diseases and raids by Peruvian enslavers in the 19th century.

New findings from Binghamton University, Lamont-Doherty Earth Observatory at Columbia University, and other institutions challenge the ecocide theory. Their study of ancient rock gardens using satellite imagery suggests that Rapa Nui's population never exceeded the numbers observed by the Dutch explorers who first arrived in 1722.

Less Agriculture, Smaller Population

To fully grasp their conclusion, one might need an overview of farming practices on volcanic islands. The first settlers of Rapa Nui arrived before 800 CE, facing harsh agricultural conditions. They cultivated root vegetables using a mix of plant waste and rock mulch as their 'soil.'

Rapa Nui covers about 40,500 acres, slightly smaller than Washington, D.C. By analyzing the extent of rock gardens on the island, researchers can estimate its maximum population. Previous studies offered estimates, such as a 2012 study by the University of Auckland, which used less precise satellite data to estimate that between 2.5 and 12.7 percent of the island was dedicated to rock gardens. This earlier research proposed the possibility of a peak population as high as 17,000, which supported the theory that ecocide led to a population collapse to the 3,000 inhabitants found when Europeans first arrived.

The authors of a new study published in Science Advances used advanced satellite data that could detect moisture and soil composition. They found that only 180 acres—just 0.4 percent of the island—were used for rock gardens, which would have supported only around 3,000 people at most, and only on a continual basis.

Challenging the Collapse Theory

The 'ecocide' theory was introduced in the early 1990s and popularized by historian Jared Diamond in his 2004 book Collapse: How Societies Choose to Fail or Succeed [PDF]. This narrative of environmental destruction seemed a fitting warning in an age grappling with climate change: A once-flourishing society, capable of producing art and engineering marvels, destroys its environment and succumbs to scarcity and conflict. As Diamond wrote, 'What did the Easter Islander who cut down the last palm tree say while he was doing it? Like modern loggers, did he shout, 'Jobs, not trees!'?

Several archaeologists and researchers have contested the ecocide theory, using radiocarbon dating and other methods to track human activity. Their findings suggest that Rapa Nui’s population either grew or remained stable until first contact. Some evidence also points to the island’s deforestation dating back to the earliest human settlers, with one theory proposing that a species of rat brought by the first settlers contributed to the destruction of the island’s forests and native fauna.

Some critics argue that the ecocide theory unfairly portrays the Rapanui people as ignorant, overshadowing the role colonialism played in their history. A notable anthropologist wrote that this narrative 'turned the victims of cultural and physical extermination into the perpetrators of their own demise.' However, with new scientific findings, this perspective is now evolving.