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Genetics Point to Pre-European Contact Between Easter Islanders and Native Americans

NEW YORK (GenomeWeb News) – A genotyping study in Current Biology suggests individuals from Easter Island, or "Rapa Nui," had contact with Native American populations prior to Europeans arriving on the Pacific island in the 1700s.

Researchers from the Natural Museum of Denmark's Centre for GeoGenetics and other centers in Denmark, the US, and Norway used SNP profiles for individuals from Rapa Nui and other parts of the world to tease apart ancestry tracts in the genomes of Rapanui individuals — a search that uncovered signs of Native American admixture believed to have occurred hundreds of years before Dutch explorers arrived on the island on an Easter Sunday in 1722.

"[E]arly human populations extensively explored the planet," co-senior author Anna-Sapfo Malaspinas, a researcher with the Natural History Museum of Denmark's Centre for GeoGenetics, said in a statement.

Based on her team's findings, Malaspinas argued that "[t]extbook versions of human colonization events — the peopling of the Americas, for example — need to be re-evaluated utilizing genomic data."

Past research suggests Rap Nui was first settled in around 1200 when between 30 and 100 Polynesian settlers arrived in double-hulled canoes during Austronesian expansions to the east, the study's authors explained.

Since then, the island has become home to a wealth of archeological artifacts, including hundreds of stone platforms and imposing stone statues. But questions remain about the methods used to produce these impressive structures.

Likewise, there are gaps in researchers' understanding of the human migrations to or from the island prior to the arrival of Dutch sailors in 1722, though some proposed early contact between Polynesian and Native American populations based on everything from overlapping technologies and crop plants to some comparable human leukocyte antigen allele frequencies.

To further explore the genetics of Rapa Nui's population history, authors of the current study assessed profiles at more than 650,000 SNP markers of 27 Rapanui individuals.

Of those, eight unrelated individuals were included in a population analysis that included genotyping data for almost 200 Europeans, New Guinea Highlanders, Native Americans, Chinese, Borneans, or Polynesians.

When they broke down admixture patterns in the Rapanui genomes, the researchers found that the individuals carried 6 percent Native American ancestry and 16 percent European ancestry, on average, while the remaining sequences resembled those in Polynesian populations.

Much of the European admixture seems to have occurred during the 1800s, a period marked by frequent exposure to visiting populations from Europe and a decline in Rapanui individuals due to newly introduced diseases and forced labor recruitment during the Peruvian slave raids in the 1800s.

In contrast, the team's population models point to Native American admixture occurring hundreds of years earlier. That, in turn, has prompted speculation that members of the Rapanui population traveled to the Americas and back prior to European colonization or that Native Americans made their way to the Polynesian island during that time frame.

Those involved in the analysis emphasized that more research is needed to untangle the nature of that interaction and to tease apart the particulars of the Native American and Polynesian groups involved.

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