Published On: Sat, Oct 14th, 2017

Mystery NOT Solved: No Trace in DNA Between Ancient Easter Island People and South America 

Mystery and intrigue surrounds the life and times of people who created the famous Moai statues on Rapa Nui off the coast of Chile — and a new study suggests they were more isolated than previously thought

 

 

The Chilean Rapa Nui dubbed Easter Island by Dutch explorers, in the southeastern Pacific Ocean, has long been a source of intrigue and mystery.

How did such a small community of people build its famous 887 extant monumental statues, called moai?
And what happened to cause that community to collapse?
The island which was first settled by Polynesians between 700-1100 AD, left a hole of knowledge which needs to be filled.

Researchers have been curious about what kind of contact the island people, known as Rapanui, might have had with South Americans prior to the arrival of Europeans.

DNA study in 2014 of the people live on the island today and archaeological evidence from sweet potato crops support early mixed between the Rapa Nui people with native Americans before Europeans arrived in 1722 AD.

But a new study, published in the journal Current Biology, finds no genetic evidence that ancient inhabitants of Rapa Nui intermixed with South Americans.

The idea that there had been early contact between the two populations, or even Southern Pacific migration route contributed to the peopling of the Americas, has been a long-standing debate in the field.

While the results can’t exclude the possibility that cultural relationship took place, if long-distance journey across the ocean did happen, “they did not leave genetic traces among the individual samples,” said Lars Fehren-Schmitz of the University of California, Santa Cruz. “We were surprised that we didn’t find any Native American blend in our ancient Rapanui examples.”

 

The researchers sequenced DNA from five early Rapa Nui islanders representing both before and after European contact, using samples taken from the Ahu Nau Nau site close to five of the famous moai statues.

Dating suggested three of these islanders lived before European contact, between 1445 -1624 AD, while the other two were dated long after European arrival on the island between 1815- 1945.

 

The researchers report that the DNA, including both complete mitochondrial genomes and low-coverage autosomal genomes, indicates that the DNA of the sampled individuals falls within the genetic diversity of present-day and ancient Polynesians.

While the older samples contained no native American DNA, there were traces of European genetic influence in the two post-European islanders.

“We can reject the hypothesis that any of these individuals had substantial Native American ancestry,” Fehren-Schmitz said. “Our data thus suggest that the Native American ancestry in contemporary Easter Islanders was not present on the island prior to European contact and may thus be due to events in more recent history.”

According to Fehren-Schmitzne, one explanation for the earlier study’s finding of native American ancestry may relate to the mixed European and South American ethnicity of the crews that were on the ships that landed on Rapa Nui.

There was also a possibility that the three ancient islanders without native American DNA just happened to be Rapa Nui who did not mixed.

It’s clear from earlier evidence that living Rapanui do have a small proportion of Native American ancestry. But, the researchers in the new study say, “it is especially difficult to disentangle movements of people in the prehistoric period from more recent times.” The question remains: How and when did this population exchange happen?

The researchers say they’d now like to generate genome-wide data from additional ancient Oceania and western South American populations. The goal is to develop a more detailed picture of the populations that lived within each of these regions and potential interactions among them.

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