Native American gene flow into Polynesia predating Easter Island settlement:
The possibility of voyaging contact between prehistoric Polynesian and Native American populations has long intrigued researchers. Proponents have pointed to the existence of New World crops, such as the sweet potato and bottle gourd, in the Polynesian archaeological record, but nowhere else outside the pre-Columbian Americas…while critics have argued that these botanical dispersals need not have been human mediated…The Norwegian explorer Thor Heyerdahl controversially suggested that prehistoric South American populations had an important role in the settlement of east Polynesia and particularly of Easter Island (Rapa Nui)2. Several limited molecular genetic studies have reached opposing conclusions, and the possibility continues to be as hotly contested today as it was when first suggested…Here we analyse genome-wide variation in individuals from islands across Polynesia for signs of Native American admixture, analysing…individuals from 17 island populations and 15 Pacific coast Native American groups. We find conclusive evidence for prehistoric contact of Polynesian individuals with Native American individuals (around AD 1200) contemporaneous with the settlement of remote Oceania…Our analyses suggest strongly that a single contact event occurred in eastern Polynesia, before the settlement of Rapa Nui, between Polynesian individuals and a Native American group most closely related to the indigenous inhabitants of present-day Colombia.
I already recorded a podcast on The Insight with the first author that should post tonight. So I’m not going to put a long post, just subscribe to The Insight and listen to what the first author has to say.
The major finding using high density SNP chips and local ancestry deconvolution seems to be that a group of people from mainland South America, probably coastal Columbia, was admixed into the population of the Marquesas. It is from the Marquesas that this genetic ancestry propagated across the eastern fringe of Oceania, including Easter Island.
Update: The podcast has been pushed live. It should propagate in the next hour or so.
So the idea here is that a group of people from continental South America found themselves on a remote Pacific island where they intermixed with Polynesians — who are still predominantly descended from Asian stock.
What’s the most likely way that group got there? It would be no surprise if the great navigators of Polynesia landed a canoe or three on South America. But what’s the mechanism behind the converse?
I’ve read articles interpreting this as Polynesian colonizers meeting Amerinds in the Marquesas rather than the more logical Marquesan voyaging canoes picking up sweet potatos and brides in Columbia.
Folks really really want the Kon Tiki narrative to be real.
Given that they colonized every speck of long-term habitable land in the tropical Pacific, I’d be shocked if Polynesians hadn’t reached the American coastline at some point late in their expansion. As Spike Gomes pointed out, this probably means they either took brides or captives (or both) from coastal Colombia, but didn’t otherwise stick around or leave any of their own people on the mainland.
We know the Polynesians had the skills to explore vast sectors of the ocean. And not only that, they needed those skills to get to the Polynesian islands in the first place. That was their thing — jumping from island to island. We have no evidence that the Amerinds every had such skills, and given that they had an entire continent to themselves they had little to gain from developing them. So it seems pretty obvious that if Amerinds ended up in the Marquesas they must have traveled there on Polynesian boats.
I haven’t read the article, but I am assuming this amerindian ancestry is on the maternal side? As some other comments have said, this is a fascinating possibility of these sea faring Polynesians picking up brides while exploring the coast of south america. On top of their ability to traverse a whole ocean with their skills and bravery, this is such a amazing story!
It is 4,000 miles from the West Coast of South America to the Marquesas
Got out of town on a boat for the Southern Islands
Sailing to reach before a following sea
She was makin’ for the Trades on the outside
And the downhill run to Papeete
Off the wind on this heading lie the Marquesas
Wow! Wilmshurst et al. 2011 established that the remoter parts of Polynesia were discovered in a single pulse 1190-1290 so it lines up nicely. This is nearly twice the distance the Marquesas are from NZ and Hawaii.
Combining the extreme distance with the fact they didn’t find the Juan Fernandez Islands or the Galapagos, they likely didn’t range so far many times. In the Equatorial Pacific, sailing East is like going uphill. One theory is they waited for rare westerlies at a certain time of year and took off confident the wind would soon enough return them home if they found nothing. Perhaps one year it just went on much longer than usual.
Can the same method be used in Iceland, where a medieval Amerindian lineage has been detected? The Beothuk would be the number one candidate but they met a tragic end nearly 200 years ago.
I’ve read articles interpreting this as Polynesian colonizers meeting Amerinds in the Marquesas rather than the more logical Marquesan voyaging canoes picking up sweet potatos and brides in Columbia.
so the podcast isn’t posted, but i talked about this extensively. they don’t know which method is true genetically obv. though he really didn’t want to say it couldn’t have been shipwrecked people.
I am noticing a certain argument here I would like to debunk:
“Amerinds did not show such navigational technology, and therefore must have been brought to the islands by Polynesian navigators”
The primary evidence of Polynesian navigation is actually linguistic and anthropological, not material. We knew these migrations happened (before genetic studies) because we found the same language family and culture distributed across various islands. There were no remnants of the actual canoes, and after 14th century, no ocean going voyages to Rapa Nui, Hawaii, or Aotearoa.
In the case of the Amerinds, mainland cultures could have been entirely replaced. We know there was a genetic turnover in South America due to the survival of a Southern ENA population in isolated areas before they were subsumed elsewhere.
It is perfectly possible that there were Amerind groups that were capable of such navigation, but at some point ceased to exist with the same cultural and technological package on the continent, and were eventually absorbed or replaced on the islands by Polynesians.
swampr: Greenland was inhabited by Native Americans from the North American Arctic at the same time as it hosted Viking settlements which communicated with Iceland.
they don’t know which method is true genetically obv
would they be swayed more in one or another direction if they knew the sex-bias of the admixture? I am surprised that this was, apparently, not looked into.
I guess that this explains Araucana chickens.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1965514/
re: sex bias. the fraction is so low tho
I, for one, DO really want the Kon Tiki narrative to be true. If for no other reason than you had someone as cool as Knut Haugland on that voyage.
re: sex bias. the fraction is so low tho
if the original autosomal admixture ration was 10% and it all came from one sex, then hypothetically 20% of mtDNA or of Y Chromosomes could be of the American origin. They have enough samples to test it, I would think. Of course Y-chromosomes are notoriously susceptible to social dominance games, so if the authors see neither Y nor mt, then it may be because the autosomal admixture came with the socially disadvantaged males, and drifted out because of it?
Aditya:
“There were no remnants of the actual canoes”
Not at all surprising or difficult to explain. The canoes were made out of wood and fiber. Wooden sailing vessels have useful lives of years, not decades. When they are no longer seaworthy they are broken or sunk. In either event the wood and fiber will not last very long in tropical environments.
“In the case of the Amerinds, mainland cultures could have been entirely replaced.”
Yes, but not in the last couple of Millennia. Pre-Columbian natives produced true civilizations with elaborate architectural remains, and in Meso-America, writing. We have pretty good time lines for Meso-American and Andean Civilizations. Neither of them were ocean going. And, there is very little evidence of contact between the two regions, even though coasting is far easier than the long distance open ocean voyages of the Polynesians.
“It is perfectly possible that there were Amerind groups that were capable of such navigation”
Anything is possible, but there is no evidence for it. Given the paucity of contact between Andean and Meso-American civilizations, it seems to be most unlikely.
One element that might favour or disfavour the “Native Columbian seafarer” record is diffusion of Austronesian package in Southern America. Did the result with Polynesians chickens in the Americas really hold up? (I think it did not – https://www.nationalgeographic.com/news/2014/3/140318-polynesian-chickens-pacific-migration-america-science/). Though if that’s the case, strange that’s the only Austronesian package element that we’ve detected.
That said, don’t the Botocudos samples confirm there probably were Polynesians in the Americas anyway?
Kon-Tiki thing seems plausible enough, but not so sure about the idea not preceded by contact by Polynesians first. You might plausibly get out there and back with some pretty basic “watercraft” but seems like you wouldn’t do so for a lark unless you thought there was a reason to.
It does seem pretty strange to me to think of Polynesians landing in the Americas, sort of “grabbing” local women or getting gifted with them by local chiefs or whatever, along with some sweet spuds and then disappearing back to an isolated island chain, to leave no local impact visible by crops, dogs, domestic animals, sailing techniques, etc.
There are some interesting adna results from June showing ongoing sea contact among the Caribbean – https://science.sciencemag.org/content/early/2020/06/03/science.aba8697 “Genomic insights into the early peopling of the Caribbean”, and preprint https://www.biorxiv.org/content/10.1101/2020.06.01.126730v1 “A genetic history of the pre-contact Caribbean”. Kendra Sirak’s study suggests “a sudden movement by a largely homogeneous ceramic-using population most likely originating in northeastern South America and related to present-day Arawak-speaking groups moved throughout the Caribbean at least 1,800 years ago, spreading ancestry that is still detected in parts of the region today. “
But I have no idea if this has any connection to the matter here. Since this suggests that a group of people from mainland South America” may have made a voyage, an influx of people with similar ancestry into the Caribbean may be interesting. Or not.
re:sex bias
What direction was the sex bias?