The stories of Ancient Polynesians and Native Americans have been intertwined for longer than previously thought. 

A recent genetic analysis shows that Ancient Polynesians and Native Americans likely came into contact through a series of voyages around 800 years ago, long before European colonizers were on the scene. Not only do the new insights connect "two of the most understudied regions of the world," but they also shed light on the mystery of how sweet potatoes migrated from the Americas to the islands of the South Pacific. 

Reported in the journal Nature today, scientists from Stanford University School of Medicine studied the genomes of over 800 people living in modern-day South America and French Polynesia using some of the latest computational methods to sift through vast vats of genetic data. This cohort included people from 17 Polynesian islands and 15 indigenous groups living along the Pacific coast of the Americas from Mexico to Chile.

Their results suggest that Native Americans and Polynesians started having children with one another between 1150 and 1230 CE. This intermingling appears to have occurred during a “single contact event" that most likely took place in eastern Polynesia between Polynesians and a Native American group closely related to the indigenous peoples of present-day coastal Colombia. Over the next few centuries, there were many more migrations from South America to Polynesia that skipped across the numerous islands of the South Pacific. 

The prehistoric links between Polynesians and Native Americans have been hotly debated for decades, and many questions about their ancient interminglings remain unanswered. The timing of this initial meeting around 800 years ago is also important as it occurred slightly before people settled on Rapa Nui, or Easter Island, famed for its giant human head monuments, which was long believed to be the point where the two cultures initially crossed paths because it's one of the closest Polynesian Islands to the Americas. However, it looks like the Native Americas actually met more eastward, most likely traveling further afield due to favorable sailing conditions. 

"If you think about how history is told for this time period, it's almost always a story of European conquest, and you never really hear about everybody else," Alexander Ioannidis, lead author and a postdoctoral scholar at Stanford, said in a statement. 

“Through this research, we wanted to reconstruct the ancestral roots that have shaped the diversity of these populations and answer deep, long-standing questions about the potential contact between Native Americans and Pacific Islanders, connecting two of the most understudied regions of the world," continued Andrés Moreno-Estrada, professor and head of genomic services at the National Laboratory of Genomics for Biodiversity in Mexico. 

Before this genetic study, the evidence that Native Americans and Polynesians had crossed paths before European colonization often came in the form of the sweet potato.

“The sweet potato is native to the Americas, yet it's also found on islands thousands of miles away," Ioannidis explained. "On top of that, the word for sweet potato in Polynesian languages appears to be related to the word used in Indigenous American languages in the Andes."

Some previously pondered whether the presence of sweet potatoes in both regions shows that Polynesians voyaged to South America, took a liking to the crop, and introduced the plant on their return to Polynesia. This new research, along with other recent studies, suggests the sweet potato actually originated along the northern coast of South America before being exported by Native Americans to the islands of Polynesia.