Lots of Sweet Potatoes Could’ve Made Easter Island a Bustling Place

When James Cook pulled ashore on a small island in the Pacific Ocean in 1774, he estimated the community of people there numbered about 600. Even to the uninformed eyes of this group of English voyagers, the isle, called Rapa Nui by natives and dubbed Paaseiland, or Easter Island by the Dutch​, appeared to be a place that had once been home to a population much greater in size. Besides its famous statues—some of which, even nearly 250 years ago, were already falling in disrepair—Cook's men also noticed that large parts of the island appeared to have once been cultivated, but now seemed to be abandoned.

For years, scientists have debated wildly on just how many people could've lived on Easter Island during its peak. Early accounts like Cook's are unreliable—just 12 years after his visit, explorer Jean-François de La Pérouse estimated the same island's population to be between 2,000 and 3,000 people, up to five times more than Cook's count. But in a book last year anthropologists George Gill and Thomas Furgeson place the scientific consensus for Easter Island's maximum population at somewhere between 6,000 and 9,000 people.

Now, new research suggests that this verdant island, only 63 square miles in size, could have supported a much larger population of indigenous people than previously thought. A recent study published in the journal Frontiers in Ecology and Evolution sheds light on how dramatic its population collapse could have been, suggesting this small island could have once supported a population of roughly 17,500 people. 

In the study, researchers examined soil samples and weather patterns to estimate the peak agricultural capacity for the island, especially its main crop of sweet potatoes, reports Daryl Worthington for New Historian. By their estimates, roughly 19 percent of the island could have been successfully cultivated for sweet potatoes, producing more food than previously thought.

"If we compare our agriculture estimates with other Polynesian Islands, a population of 17,500 people on this size of island is entirely reasonable," lead author Cedric Puleston said in a statement.

While Peter Dockrill of ScienceAlert notes that there's no evidence to suggest that many people ever actually lived on the island, researchers say their findings offer valuable insight into the ongoing mystery surrounding Easter Island. “We’ve tried to solve one piece of the puzzle – to figure out the maximum population size before it fell,” Puleston says.

That fall, somewhere between the populations's peak and the 18th century, is when the island's population seems to have plummeted for reasons still unknown. Some scientists have hypothesized that the island's people decimated each other through infighting, while others have drawn parallels to the current struggles of planet Earth by blaming overuse of the environment.

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Ben Panko is a staff writer for Smithsonian.com