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Dec 18th 2020

Genome Analysis Confirms Ancient Cultural Connection

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Human history is complicated. Experts seeking to understand how, what, when and where we discovered tool use or lost our forebearers’ fur are continually constrained by limited evidence. While prehistoric preservation provides some parts of the puzzle, historians face the challenge of not knowing exactly how the pieces fit together — or what the whole picture looks like.

Recent genome analysis, however, has helped shed light on one contentious question: Did ancient Polynesians ever meet Native Americans? As it turns out, the evidence is clear: They connected in Colombia.

Po-ta-to, Pa-tah-to

The oceanic/South American meetup has been floated before, but reactions were consistently mixed. Why? Because the tale rested on a tuber technicality.

As noted by Science magazine, sweet potatoes were originally domesticated and grown in the Andes of South America, but also cropped up in one other place before Europeans arrived: Polynesia. This potato plurality plus a similar-sounding word for these veggies in Polynesian and Indigenous American languages gave rise to the idea that oceanic explorers could have made their way across the Pacific and found new friends on the shores or outlying islands of western South America.

The problem? These potato data points were largely circumstantial. Attempts to analyze their origins didn’t answer the question — as it turns out, potato genetics are too complicated to solve for their shared or separate spread across the Southern Hemisphere. This left scientists in an evidentiary bind: While one ancestral analysis of Rapa Nui residents (also called Easter Island) revealed Native American connections, another showed seemingly no connection, and DNA analysis of ancient bones also came up short.

With potatoes out of the picture and no definitive DNA determination, a new approach to human history was required: genome analysis.

Masters of Wind and Wave

According Smithsonian Magazine, one thing historians can agree on is that Polynesian explorers were skilled enough to find and settle islands spanning more than 16 million square miles of the Pacific Ocean. They made it all the way to Rapa Nui — 2,300 miles from the coast of Chile — meaning it’s certainly within the realm of possibility that they pushed on to South America. Studies have also suggested that Native Americans could have made the trek westward into the Pacific but this is less likely since most of their watercraft were designed for close coastal fishing and travel.

To solve this relational riddle, scientists from Stanford Medicine turned to big data, deep-genome analysis in their paper, “Native American gene flow into Polynesia predating Easter Island settlement.” As noted by the study’s co-lead author Alexander Ioannidis, “Genomics is at a stage where it can really make useful contributions to answering some of these open questions.” The team collected saliva samples from 807 participants from 15 Native American groups on the Pacific coast and across 17 Polynesian islands, and then went hunting for snippets of DNA that were “identical by descent” — inherited from the same common ancestor.

The technique paid off: Genome analysis found that Polynesian and South American peoples met around A.D. 1200, most likely in what’s now Colombia, and produced children that shared genetic heritage, giving rise to the long tail of DNA history. While it’s impossible to pinpoint the exact time and place of this cultural connection, the evidence is clear — before Europeans ever made their cross-Atlantic journey, the masters of wind and wave conquered the Pacific.

Navigating a New Narrative

Beyond the benefits of connecting the dots on circumstantial potato progenation to inter-cultural meet-and-greets, there’s a broader impact here: New perspectives on historical narratives.

Ioannidis puts it simply: “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.” Both South and North American exploration are typically couched in terms of European endeavors — with mentions of the Vikings tossed in occasionally for good measure — but there’s a deafening silence around the interaction of other Indigenous groups across the globe.

In effect, genome analysis is helping researchers broaden their understanding of human history by providing parallel stories of exploration and shedding new light on our deep-seated drive for discovery.

Check out Northrop Grumman career opportunities to see how you can participate in this fascinating time of discovery in science, technology, and engineering.

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