12 October 2017
Andrew Masterson
Andrew Masterson is a former editor of Cosmos.
The people of Easter Island did not fraternise with South Americans before the arrival of Europeans in 1722, a new paleogenetic analysis has established.
The surprising finding, reported in the journal Current Biology, helps to further illustrate the mysterious culture of the Polynesian people who left the remote island dotted with instantly recognisable towering “moai” figures.
A team led by anthropologist Lars Fehren-Schmitz from the University of California, Santa Cruz, in the US, analysed fragments from five human skeletons excavated from the island in 1980 and held in the Kon-Tiki Museum in Oslo, Norway.
Three of the skeletons date to before European arrival, and two after.
The scientists aimed to further examine evidence uncovered in 2012 that the Polynesian Easter Islanders had mixed with Amerindians before Europeans arrived on the scene.
The 2012 research, conducted Erik Thorsby of the Institute of Clinical Medicine in Norway, used blood samples from living Easter Islanders and analysed antigens, mitochondrial DNA and Y-chromosome markers.
Thorsby reported that all the individuals carried distinctive Polynesian markers, but that some also carried particular antigen markers that had previously only been found in Amerindian populations.
The research suggested that the Amerindian markers had entered the Easter Islanders’ genome before known contact between the two cultures – arising from the Peruvian slave trade around 1860 – and that the additions had possibly occurred in “prehistoric time”.
Another study narrowed the margin for contact between the islanders and the Amerindians, finding that it most likely occurred between 1280 and 1425.
These results were not considered controversial. Evidence suggests that Polynesians arrived on the island perhaps as early as 700CE, and that, for a seafaring culture, the 3680 kilometres of ocean separating them from the South American mainland would not have been unconquerable.
The latest analysis, however, throws the intermixing theory into doubt.
“We found no evidence of gene flow between the inhabitants of Easter Island and South America,” says Fehren-Schmitz.
“We were really surprised we didn’t find anything. There’s a lot of evidence that seems plausible, so we were convinced we would find direct evidence of pre-European contact with South America, but it wasn’t there.”
The results for the moment raise more questions about Easter Island, or Rapa Nui, as their modern day descendants prefer to call it. For Fehren-Schmitz, they serve as a strong prompt for further investigation.
“We want to do more work to determine more precisely when this gene flow between Native Americans and the people of Rapa Nui occurred, and where in the Americas it originated,” he says.
“The population dynamics of these regions are fascinating. We need to study the ancient populations of other islands — if remains exist.”