Rapa Nui’s dramatically improbable moai have attracted global attention, and deservedly so—their iconic appeal is undeniable, and to contemplate how such an isolated people could create them and, without benefit of the wheel or draft animals, transport them across rugged terrain and erect them on massive platforms excites the imagination. These matters, though, often distract visitors from even bigger but ultimately related questions—the regularity and direction of cultural contacts across the Pacific, how and when the first immigrants arrived at this remote speck of land, and how an apparent handful of people created a society with monuments that seem far likelier in empires with millions of inhabitants.

The peopling of the Pacific is a complex topic, and its relationship to the Americas even more complex. In the remote past, as humans spread out of Africa to inhabit Europe and Asia, they eventually reached North America via a land bridge across the Bering Strait before dispersing throughout the Caribbean and South America; by at least 12,000 years ago, when melting continental glaciers and rising seas closed the land bridge, humans had occupied the entire Western Hemisphere, even if their density was low. Over succeeding millennia, societies and civilizations in the Eastern and Western Hemispheres developed in geographical isolation.

Columbus’s voyages across the Atlantic ended this isolation forever, but it had never been complete. Vikings had reached Greenland and Labrador around the end of the first millennium A.D., but Polynesians may have reached South America even earlier. Or vice-versa, according to speculations by the likes of Norwegian adventurer Thor Heyerdahl, who claimed pre-Columbian South Americans sailed west to Polynesia.

In this larger context, Rapa Nui fits into the long-standing academic controversy between advocates of “independent invention,” who emphasize the parallel development of cultures separated by the oceans, and adherents of “diffusionism,” who argue the importance of pre-Columbian contacts. As in many academic debates, there are political overtones, as diffusionists often stand accused of disparaging the ostensibly derivative achievements of New World peoples.

In 1947, on his famous Kon-Tiki raft voyage, Heyerdahl proved it possible to sail west from South America to Polynesia with the help of prevailing currents. Still, he never really proved that was how it happened; the pre-Columbian sailing tradition in the Americas, although it covered distances as great as those from Peru to Mexico, was primarily coastal. Still, there is material evidence of movement in both directions—key economic plants, most notably the tropical coconut and sweet potato (the latter an American domesticate), were present in both hemispheres in pre-Columbian times.

It is likelier that, with their elaborate seafaring tradition, Polynesian islanders reached Rapa Nui first (though it’s conceivable they did so after crossing the Pacific to Peru). What seems clear is that voyages across the Pacific, in spacious double outriggers capable of carrying food, water, and domestic animals, took place on a basis of knowledge and skill. They were not fortuitous—trans-Pacific sailors were unlikely to have survived a long voyage for which they had not planned. By observing currents, winds, clouds, and the flight patterns of birds, they could often infer the existence of land at great distances.