Polynesians and Native Americans met 800 years ago
July 9, 2020 8:04 PM   Subscribe

Native South Americans were early inhabitants of Polynesia "DNA analysis of Polynesians and Native South Americans has revealed an ancient genetic signature that resolves a long-running debate over Polynesian origins and early contacts between the two populations."
posted by dhruva (42 comments total) 30 users marked this as a favorite
 
There is a useful accompanying Twitter thread from archaeologist Molle Guillaume; he...disagrees with some of the methodology and conclusions in this scholarship: https://mobile.twitter.com/molleguillaume/status/1280990641053302785

One of the authors of the Nature article, Andres Moreno-Estrada, defends the article in this Twitter thread: https://mobile.twitter.com/morestrada/status/1281363858310004736: "We cite Heyerdahl, along with others, but we do not support his broad theory. We describe 2 possibilities: Native Americans, whose coastal voyaging is little appreciated, but did exist, drifted west, or Polynesians, whose voyaging prowess we describe, sailed east & returned."

A central point of the current debate pivots around the legacy of Thor Heyerdahl (Previously on Metafilter).
posted by toast the knowing at 8:25 PM on July 9 [9 favorites]


An interesting and relevant aside:

The sweet potato is often brought up as a potential indicator of pre-European contact between Polynesians and indigenous people of South America. However, there *are* native Ipomoea species (Ipomoea is the genus of sweet potatoes) in the Pacific Islands (e.g. Hawai‘i has three indigenous and one endemic species) which would suggest it's not too difficult to imagine sweet potatoes colonizing Pacific islands on their own.

(other than the general biogeography stuff this is nowhere near my own expertise but I do think it's *extremely* probable that there was pre-European contact)
posted by deadbilly at 9:33 PM on July 9 [3 favorites]


“it's not too difficult to imagine sweet potatoes colonizing Pacific islands on their own.”

I admit that I haven’t read the links yet but this is an amazing sentence. I want to believe in this secret history of yam colonialism.
posted by mhoye at 9:42 PM on July 9 [34 favorites]


I find it extraordinary that anatomically modern humans have been around for hundreds of thousands of years, and yet this admixture took place less than a thousand years ago. The Polynesians and the Europeans were not in contact with each other and there was no flow of technology between them (as far as we know), yet the Polynesian completion of the first human circumnavigation of the globe was only around five hundred years before Magellan - less than a tenth of one percent of humanity's existence. How astonishing!
posted by Joe in Australia at 10:13 PM on July 9 [2 favorites]


yet the Polynesian completion of the first human circumnavigation of the globe was only around five hundred years before Magellan - less than a tenth of one percent of humanity's existence. How astonishing!

The Polynesians crossed the Pacific and part of the Indian Ocean. There is no evidence that they ever entered the Atlantic Ocean, so circumnavigation of the globe is a bit of a stretch here. It's honestly very likely that Magellan's crew were the first humans to complete that trip.
posted by jmauro at 10:18 PM on July 9 [1 favorite]


I'm imagining the Ship-Kings of the yams, most honored among vegetables.
posted by tavella at 11:04 PM on July 9 [8 favorites]


(okay, yes, the sweet potato is the name of the SA branch of the family, but yam is just inherently a funnier word.)
posted by tavella at 11:05 PM on July 9 [1 favorite]


I think the fact that the Polynesian word for sweet potato is obviously derived from the Quechua word is a pretty big hint that there was cross-cultural contact.
posted by Harvey Kilobit at 11:07 PM on July 9 [9 favorites]


I want to believe in this secret history of yam colonialism.

Interestingly, the sweet potato brought the Quechua word for themselves in their Pacific travels. Perhaps they had domesticated the Quechua into being their communication commensuals. (on preview, what Harvey Kilobit said)

This new paper is actually super interesting: it has been known for years that there was cultural contact between Polynesia and western South America: not just the sweet potato, but domestic chickens from the 15th century CE have been found in Chile, at least a century before Europeans would have arrived in the area, and these chickens share genetic signatures with Polynesian chickens (themselves as SE Asian domesticate). The transport of crops and language back from, and of living chickens to the Americas, strongly suggests more than transient knowledge and contact. A logical next step of this would be the physical movement of people back and forth as well, and this new paper is interesting in that it attempts to put a time frame on this.

The apparent genetic mixing between these populations, separated by at least 15,000 years of Pacific Rim human expansion, apparently takes place in Central Polynesia, before the Polynesian settlement of Rapa Nui. The margins for error in these kinds of estimates (both genetic chronologies and determining the "oldest" archaeological site on an island) are fairly loose, at least century scale, so the difference beteen 1200 and 1400 CE is very hard to distinguish, yet crucial to the story they are telling. However, it may be worth noting that the oldest evidence for sweet potato in Polynesia also comes from central Polynesia and predates the apparent discovery of Rapa Nui by a century or two.


While a little confounding, the study makes more sense in the context of the Polynesian strategy of "upwind exploration" in which, broadly speaking, exploration vectors were approximately East South East, meaning that central Polynesian expansion was more likely to strike Peru before before finding Rapa Nui, and Rapa Nui exploration was more likely to strike Chile. The sweet potato genetics and the distribution of the Quechua language strongly favour the NW South American initial landing point.

And four centuries after Polynesians discovered Rapa Nui then Europeans re-discovered it, and in the subsequent centuries Polynesians played a prominent role as hired sailors as well as involuntary or slave sailors in all dimensions of Pacific trade. No one knew the ocean as well as them until the 19th century. So untangling this complex genetic legacy is going to require a lot more study.

In contrast, there is zero evidence for Heyerdahl's model and the authors of this piece are incredibly naive in their assumptions underlying even taking it seriously. Remember Heyerdahl had to be towed offshore by the Navy even to leave South America, had effectively no directional control over the raft, survived a crash landing in Polynesia only with the aid of the local population, and, most importantly, knew in advance there was land 4,000 km away. If they want to take Heyerdahl seriously and have us take them seriously, they really need much more than the superficial hand-waving they do and to drill down into the weird world of hyperdiffusionism in archaeology and the unfortunate, if kind of exciting, series of experimental voyages of Heyerdahl and his ilk.
posted by Rumple at 11:19 PM on July 9 [24 favorites]


circumnavigation of the globe is a bit of a stretch here

Humanity's circumnavigation of the globe was completed by the Polynesians. At that time, apparently only about a thousand years ago, humans whose ancestors had been engaged in a slow dispersal eastwards first met their counterparts who had been slowly spreading towards the west. That's something worth noting, as is the fact that although European and Polynesian technology were so separated their abilities practically arrived at the same point simultaneously.
posted by Joe in Australia at 11:35 PM on July 9 [6 favorites]


Here in Aotearoa/New Zealand, this paper is being greeted with a mixture of "well DUH" from Māori and irritation from local historians and scientists at these researchers whose interpretation seems to completely ignore existing research.
posted by i_am_joe's_spleen at 12:25 AM on July 10 [14 favorites]


I'm not exactly following you Joe in Australia, as I believe the common theory about the settlement of South America comes across the Bering Straight and then down the continent, not across the Atlantic?
posted by Carillon at 12:39 AM on July 10 [2 favorites]


The disagreement with some archaeologists seems to be not the genetic analysis but the hypothesis around where the mixing occurred.

First the paper shows genetic evidence of mixing between South American populations and Polynesian populations.

Specifically:
-There are genetic signals associated with Northern South America and Mexico in the DNA of the people of Rapa Nui.
-There are also signals associated with Southern South America
-There are signals associated with Europe.
-The Southern South America but not the other signals are correlated with proportion of European signals.

This indicates that the Colombian/Mexican contact event was not associated with modern era contact while the Southern signal is associated with Chilean control of Rapa Nui. This signal also varies little between Rapa Nui individuals which indicates an older admixture event. Also, this signal but not the Southern signal is also found in the Marquesas and other Eastern Polynesian populations.

Further, the dating (although this is less certain) of the admixture is earliest in the Eastern Marquesas (AD 1150).

There are a few other things in the paper which do not rely purely on genetic evidence though.

First, the hypothesis that this happened before the settlement of Rapa Nui depends on the hypothesis that this island was settled once, that there were no return voyages, and that there were no trade links.

While there is some evidence for that, there is also some evidence that Central Polynesian voyagers did know that there was an island there. It is notably the only island located on the voyaging diagram produced by master navigator Tupaia when he voyaged with Cook that is way off. It is now thought that Tupaia was creating a whole new hybrid system of geographic referencing that attempted to express some of his navigational knowledge in a system that he thought would be comprehensible to European navigators (see: this fascinating paper). The evidence from that would indicate that:
-His understanding of the geography of central Polynesia was essentially complete
-He had voyaging directions to Hawai'i
-He did not know of Aotearoa / NZ, although certainly the Maori did know of their own ancestry and he was able to communicate with them.
-His voyaging diagram did include what may have been Rapa Nui but not quite in the right place

There are alternative explanations for that:
1) He genuinely didn't know exactly where it was because it had been too long since anyone had made that journey and returned
2) He did know but the fact that he was attempting to translate his navigational knowledge into a hybrid system that would be understood by Cook and the significant distance meant that an error crept in (in other words, he could have successfully navigated to Rapa Nui if he'd wanted to)
3) He genuinely didn't know, the island identified as most likely Rapa Nui is his diagram was actually something else and the journey to Rapa Nui was only ever one way.

Of course, if either 3 is true (or less strongly, there was contact but it was very weak and not enough to maintain a genetic link) then the admixture must have happened before Rapa Nui was settled.

The second thing is that the genetic evidence alone obviously cannot answer the question of how the contact happened.

The authors posit that a possible explanation for this is that there was an ancestrally South American population on Fatu Hiva in the Eastern Marquesas who arrived through a drifting trading raft (basically the Heyerdahl hypothesis). I find that a bit puzzling, and clearly the archaeologists do as well. That's because people have looked for that evidence (there is local oral history that their ancestors came from the East) and not found it.

What the authors put forward as the alternative, I would think actually the most likely:
a) Polynesian voyagers reached Central America / Northern South America by sailing East during the brief season when winds are in that direction. (n.b. we know that voyagers traditionally explored to the East during this season, knowing that the prevailing winds would soon return to let them return West, whether or not they had found any land to stay at) then returned to the Marquesas.

b) (another alternative) Polynesian voyagers reached South America by sailing way South and then South East to pick up the Westerlies, sailed North along the coast with the trade-winds, but only stopped and mixed with locals when they reached a part of the coast which was suited to resupply and repairing their boats. They then sailed back to the Marquesas. This would be a much longer voyage.

I actually think that these are better explanations of Marquesas oral histories about Eastern ancestry than the raft hypothesis.

The raft hypothesis would require the oral history to have picked up only the from the East element without any memory of the fact that some of their ancestors were already there on the island when another group arrived! I'm not sure that's credible because that's quite an important piece of history to just forget about and it would have been much more recent than the actual arrival from the East.

Is it not more likely that voyagers travelled to and from the coast of the Americas, bringing people back with them and that this is where the "ancestors from the East" oral history comes from?
posted by atrazine at 2:24 AM on July 10 [34 favorites]


Oh and the headline in the linked News and Views article is way, way stronger than the title of the actual paper which is Native American gene flow into Polynesia predating Easter Island settlement

The News and Views headline Native South Americans were early inhabitants of Polynesia

Implies greater certainty about the raft hypothesis than I think the paper justifies.
posted by atrazine at 2:30 AM on July 10 [2 favorites]


There is also the shared musical phenomenon of panpipes as constructed and played in the Andes and in Oceania. The practice of playing in hockets (single melodies played in fragments between two people)

This article (PDF) states "specialists have noted that panpipes in South America and Oceania display substantial similarities (e.g. the arrangement in two rows, dual instruments and the use of a cane splint to hold the
tubes together... Precolumbian contacts have been thoroughly debated ... Examples include the presence of Austronesian genes in some Amazonian Native American societies ... and
pre-European admixture of Polynesian and South American genes in Rapanui ... the patterns of diffusion of the sweet potato into Oceania ... and the introduction of Polynesian chickens into Chile.."

Another technology which is pretty specific and points to the advanced kntting and weaving arts of indigenous South America is the making of "knotless nets" in the Andes and Oceania. (PDF File)

Apparently the jury is still out on Aracaunian chickens.
posted by zaelic at 2:33 AM on July 10 [8 favorites]


Rumple: In contrast, there is zero evidence for Heyerdahl's model and the authors of this piece are incredibly naive in their assumptions underlying even taking it seriously.

There have been other high profile cases of geneticists working on archaeological questions drawing the conclusion from whichever weird racist theory had currency in the pop science of their youths.
posted by Kattullus at 2:44 AM on July 10 [2 favorites]


Heyerdahl was all over the Discovery Channel television empire in the 90s.
posted by Kattullus at 2:47 AM on July 10


“it's not too difficult to imagine sweet potatoes colonizing Pacific islands on their own.”


Are you suggesting sweet potatoes migrate?
posted by Ghostride The Whip at 2:59 AM on July 10 [10 favorites]



Are you suggesting sweet potatoes migrate?


i yam what i yam i'm popeye the sailin' tater
posted by lalochezia at 4:20 AM on July 10 [10 favorites]


There have been other high profile cases of geneticists working on archaeological questions drawing the conclusion from whichever weird racist theory had currency in the pop science of their youths.

This is indeed a very relevant example. Genetic research of this kind really needs to be cautious about what it does and does not prove but that is not, I think, a good example of "drawing the conclusion from whichever weird racist theory had currency in the pop science of their youth".

First, David Reich was born in 1974 and has essentially spent his career spearing most of theories which were popular in his youth and before.

Second, there is a quote in that article, blithely tossed off at the end, about his work leading to conclusions “indistinguishable from the racialized notions of the swashbuckling imperial era” which is frankly a completely outrageous comparison to make. It is particularly outrageous when one makes it about someone who wrote an entire book about how imperial era ideas about race and ancestry were complete nonsense merely on the basis of a purely coincidental resemblance between one particular imperial theory and the DNA evidence from a single paper.

What it is a good example of is the danger, especially in the porous boundary between academic science and pop science, of over-stating what the evidence shows. The population turnover theory in (that paper is based on an analysis of 11 individuals spread over three islands. Pretty good actually for data that old but still needing to be treated with some caution.

The main disagreement between academics in that case was between Reich's view that he was just doing genetics work and that it was up to archaeologists to use that to form a complete picture of how things actually happened and (some) archaeologists' view that to form a picture one needed to consider archaeological, linguistic, and genetic data side by side rather than take the genetic data for granted and then sketch in the details with the other data.

I can sympathise with both views, particularly because in that case the combination of the genetic data and the other data seems to lead to a rather strange situation where most of the population was replaced but the incoming population adopted most of the language and culture of the people they replaced. That seems unusual.

I do think that geneticists do a bit of Motte and Bailey arguing in cases like this. To get the attention of Nature, they need to make big claims but when challenged on whether the evidence really supports that, they can retreat to a more modest position of only analysing the genetics.
posted by atrazine at 4:36 AM on July 10 [12 favorites]


To second atrazine, I haven't read the NYT article, but I am both very familiar with racist ideas of population and I have read Reich's book, and his book does not support them whatsoever (and he addresses them at length).

Back to the FPP: this is absolutely fascinating, and yet not (too) surprising. Whether it was that Polynesians travelled to South America or the two populations met in Polynesia, it makes sense that they would have met. For too long, the racist attitude has been that the rest of the world was just out there sitting passively, waiting for Europeans to "discover" them - which is ridiculous. They were doing their own exploring and discovery.
posted by jb at 6:07 AM on July 10 [4 favorites]


The presence of kumara in Polynesia has been one of the huge question marks in this part of human history. The simplest explanation is Polynesia traders got as far as South America and returned. And if that happened, you have to believe there was some genetic mixing too. It certainly seems plausible, even likely. OTOH it's very important to do the science right and get the details. Pinning it down to 1150-1230 is a pretty remarkable result. So is mapping out the spread of those genes.

I didn't see this in the articles I read; is there any evidence for Polynesian DNA on the South American mainland? Everything I saw is all about South American DNA on Polynesian islands. If Polynesians did reach South America you'd expect their DNA to be there, too. Maybe not much though, maybe it got diluted to invisibility. Or maybe if there was only one or two contacts, no progeny survived. That's a grim thought.

Wanted to highlight one specific criticism in Molle Guillaume's tweet thread:
no context nor information on the 1980s sampling process on Polynesian populations who by that time were not required to give their consent. Let’s not forget that people who gave their blood samples have family and personal trajectories that matter.
I'm fuzzy on the details of this now, but Reich's book talks about it. Unethical collection of human tissue samples led to a very long standing distrust that taints all science done even now.
posted by Nelson at 7:02 AM on July 10 [3 favorites]


Humanity's circumnavigation of the globe was completed by the Polynesians. At that time, apparently only about a thousand years ago, humans whose ancestors had been engaged in a slow dispersal eastwards first met their counterparts who had been slowly spreading towards the west.

The Polynesians, whose ancestors came east from Southeast Asia, met the Native Americans, whose ancestors came east from Northeast Asia. For the first meeting of people whose ancestors traveled in a generally western direction out of Africa and people whose ancestors traveled in a generally eastern direction out of Africa, the candidate that comes to mind is the meeting of the residents of Newfoundland and Vikings, about 1000 years ago.

Of course, whether "circumnavigation" at near-polar latitudes is all that impressive is questionable, given the shorter distances up there - but it was the first time the eastern-moving peoples and western-moving peoples reconnected.
posted by timdiggerm at 7:03 AM on July 10 [3 favorites]


Unethical collection of human tissue samples led to a very long standing distrust

I skimmed back through Reich's book to pick up what I remembered from reading it. I don't think it includes Polynesians in the 1980s, and now I'm curious what that particular story is. Reich references several problems with informed consent for DNA collection. They include the Karitiana in 1987 and 1996 (Amazonia) and the Havasupai in 1989 (US Southwest). Navajo Nation passed a ban on genetic research back in 2002 in response to fear of abuses.

I think genetic research is super important for medicine and I think DNA anthropology is a fascinating and important tool. I hope that all peoples on the planet agree to let their DNA be sampled (with appropriate privacy safeguards). Some of those DNA samples will undoubtedly overturn long-cherished cultural beliefs. But that's scientific progress, and I think science should take precedence over cultural myths. (Which puts me at odds with many cultures.)

However, that work has to be done with respect for the people and cultures you're taking samples from. You can't lie to your subjects or steal their DNA. Thankfully the current generation of researchers has mostly agreed to that ethical code but it's caused some big holes in our current genetic records. Mostly because of the taint sewn by scientists in abusing the trust of people in the past.
posted by Nelson at 7:59 AM on July 10 [2 favorites]


no context nor information on the 1980s sampling process on Polynesian populations who by that time were not required to give their consent. Let’s not forget that people who gave their blood samples have family and personal trajectories that matter.

Apparently the results were shared first and in-person with the people of Rapa Nui who donated the samples, so while that is indeed a potentially serious issue I think they did it correctly here. (Note that to be fair to the original tweeter, that detail was not in the paper and not in Nature News and Views article about the paper)
posted by atrazine at 8:59 AM on July 10 [1 favorite]


but it was the first time the eastern-moving peoples and western-moving peoples reconnected.

The timing of Norse arrival in Newfoundland and of the sweet potato in central Polynesia is probably within the margin of error of absolute dating methods*. But it is a grand coincidence that you see the Americas rediscovered from opposite ends at the same time.

*The new 14C calibration curve may help a lot with this. For the Pacific the game changer may be the new Uranium Thorium applications to coral abrader stones where resolution may be to less than a single decade. This has helped determine the order of settlement of the various islands within Tonga, for example.
posted by Rumple at 9:17 AM on July 10 [6 favorites]


I also want to add, the exploration and settlement of the Pacific by Polynesians is one of the greatest, if not the greatest, accomplishments in the history of human beings. It is a combination of brains and guts comparable to the moon landings - if people had had to discover the moon from spaceships first. It is severely under-rated in Euro-centric histories. And as a case study in the present of the intersection of traditional knowledge, oral history, archaeology, genetics, paleoclimatology, conservation biology, the Anthropocene, and the politics of the present day it could be taught in depth in every high school in the world to great effect.
posted by Rumple at 9:33 AM on July 10 [25 favorites]


This is very true. One of the reasons it's always seemed so overwhelmingly likely that there was some contact is that it is hard to believe that the greatest navigators in all known history would not have reached the continent, given the places they did reach. It's true that they didn't settle the Galapagos, but wind and currents apparently make that hard to get to, while NA and SA are a wall -- you can't miss hitting something if you keep going east.
posted by tavella at 9:45 AM on July 10 [2 favorites]


The authors present two options, one that the Polynesians sailed to S. America and returned, the other that the S. Americans sailed to the mid-Pacific and the two cultures met in the middle (simplified).

My question is this. We know that the Polynesians were amazing sailors and navigators, so the the first option seems highly likely. What is the evidence that the native S. Americans explored a significant part of the Pacific?
posted by CheeseDigestsAll at 9:50 AM on July 10 [1 favorite]


It's true that they didn't settle the Galapagos, but wind and currents apparently make that hard to get to, while NA and SA are a wall -- you can't miss hitting something if you keep going east.

I had to look it up to confirm, but it seems that the Galapagos are lacking in fresh water. Maybe people visited them (whether from the Americas or from Polynesia) and decided just not to stay?

I also want to add, the exploration and settlement of the Pacific by Polynesians is one of the greatest, if not the greatest, accomplishments in the history of human beings. It is a combination of brains and guts comparable to the moon landings - if people had had to discover the moon from spaceships first.

I am in awe of their voyages.
posted by jb at 11:22 AM on July 10


Easter Island also doesn't have good sources of fresh water, they used seaside fresh water seeps, but Polynesians colonized it, and San Cristobel island in the Galapagos islands has a fresh water lake. But apparently it's a lot easier to reach the Galapagos going west rather than east, so it was probably a combination of not having a permanent colony on the SA coast as a base, being on the far eastern fringe of the expansion, and not being a particularly tempting bit of land.
posted by tavella at 11:48 AM on July 10 [1 favorite]


It's honestly very likely that Magellan's crew were the first humans to complete that trip.

It's possible that the first actual circumnavigator was a Malay, Enrique.

Magellan bought him as a slave in Malacca, in 1511. He accompanied Magellan to Spain, and then on the circumnavigation attempt in 1519–21. He made it at least as far as Cebu, where Magellan was killed, and Enrique took off. We don't know if he actually made it back to Malacca, but it certainly makes a better story if he did.
posted by zompist at 2:25 PM on July 10 [5 favorites]


So the best evidence I am aware of for South American travels into the Pacific are based on a posited voyage/s (Most likely either desperation voyaging or washed away) from Ecuador to Rapa Nui or another or the Pacific edge Islands, with Kumara transitioning in this manner.

-Ecuador has the much hyped balsa wood, alongside a boat building tradition applicable to this travel, in addition the voyage would be parsimonious considering general winds and currents.

-Building style; most obviously on Rapa Nui, one of the Marae has been built with pillow faced stonework and decorative inset corner blocks, the style is recognisably Incan and not present in the Pacific.

-The Birdman motif - the Birdman motif and facing/mirrored character representation in decorations does not have an evolutionary pathway from the Pacific, but it does from Ecuador and related areas of South America. This dual facing Birdman motif can be found in Ecuador, on at least one near coastal island to Ecuador, on Rapa Nui, and then with some dispersion in the Pacific with most characterisation as traded goods.
posted by fido~depravo at 1:47 AM on July 11 [3 favorites]


related AskMeFi post on seeking book recommendations
posted by dhruva at 1:33 PM on July 11


We can add coconut populations to the evidence of not necessarily Polynesian, but more likely Austronesian contact with South America:
Genetic studies of coconuts have also confirmed pre-Columbian populations of coconuts in Panama in South America. However, it is not native and display a genetic bottleneck resulting from a founder effect. A study in 2008 showed that the coconuts in the Americas are genetically closest related to coconuts in the Philippines, and not to any other nearby coconut populations (including Polynesia). Such an origin indicates that the coconuts were not introduced naturally, such as by sea currents. The researchers concluded that it was brought by early Austronesian sailors to the Americas from at least 2,250 BP, and may be proof of pre-Columbian contact between Austronesian cultures and South American cultures, albeit in the opposite direction than what early hypotheses like Heyerdahl's had proposed. It is further strengthened by other similar botanical evidence of contact, like the pre-colonial presence of sweet potato in Oceanian cultures.[25][22][32] During the colonial era, Pacific coconuts were further introduced to Mexico from the Spanish East Indies via the Manila galleons.[20]
. . .

In attempting to determine whether the species had originated in South America or Asia, a 2014 study proposed that it was neither, and that the species evolved on coral atolls in the Pacific. Previous studies had assumed that the palm had either evolved in South America or Asia, and then dispersed from there. The 2014 study hypothesized that instead the species evolved while on coral atolls in the Pacific, and then dispersed to the continents. It contended that this would have provided the necessary evolutionary pressures, and would account for morphological factors such as a thick husk to protect against ocean degradation and provide a moist medium in which to germinate on sparse atolls.[33]
Note that this contact is thought to have taken place more than 2000 years ago at the latest.
posted by jamjam at 4:42 PM on July 11 [4 favorites]


In a certain limited sense, having the encounter be in the Marquesas is more parsimonious since it only requires one long journey rather than two but in another sense it is actually less parsimonious since it requires the people of the Central and South American coast to have navigation and open water boating technology that they were not known to have. Given the geography of much that coast, it's not even that surprising that it was not developed since it's not that useful.
posted by atrazine at 10:10 AM on July 12 [1 favorite]


The west coast of South America is almost devoid of small, nearshore islands which create the optimal conditions for development of watercraft, in effect being a rewarding nursery for putting energy into this technology. Compare to SE Asia, where the earliest known sea-going cultures developed over 60,000 years ago: especially at Pleistocene lower sea levels there were innumerable small (and large) islands creating complex ecosystsems and stepping stones to maritime adaptation. For similar reasons, Madagascar was not discovered by people until about 2000 years ago, and the first arrivals were not from Africa, with its straight, relatively island free coastline, but from SE Asia (linguistically, closest known relatives would be Indigenous Austronesian peoples of Borneo, closely related to the Polynesians themselves).

Regarding the South American influence on Polynesia, which is what got Heyerdahl started, some of this may be the result of random drifting of rafts but I doubt it. If some South Americans voyaged back with the Polynesians, consistent with the genetics, then as "distantly exotic foreigners" with different knowledge it is entirely possible they brought some of their artistic styles etc with them. It is not the case that all cultures of all time have been suspicious of foreigners or xenophobic! It would be interesting if the genetic studies under way per OP's link could look into mtDNA (maternal) vs Y-chromosone (paternal) associations to see if it was mainly men or women coming from the Americas.

In any case, South America north of south-central Chile has an extremely rich marine ecosystem with deep water upwelling and the famous anchovy fisheries which are the largest single-species fisheries in the world. Being dependent on upwelling, this fisheries is a nearshore one and even manageable from shore in distant times (nets and anchovy remains found as early as 12,500 years ago in coastal Peruvian archaeological sites). The strong Humboldt current sweeps north along the sub-equatorial coast before bending to the west. This is what the Kon Tiki drifted on. However, the nearest shore elements of this current will carry you along up the Colombian and Panamanian coasts, and you will always be in sight of land. You need to get 10 to 20 km offshore before you will be carried off to sea (probably a feature, not a bug, given the unlikelihood of a successful drift). So it's a very one-dimensional marine environment in which sophisticated watercraft or marine skills are not required and for which there is no evidence they developed. This is not to say the marine resources were not used: see for example the "Maritime Origins of Andean Civilization" hypothesis.

(The southern cone of the Americas has a rich, long term seafaring tradition but the main boats used were made of elm bark and while seaworthy probably were not capable of multi-week ocean voyages, and, further there was only a nearshore strip of coastal islands and not a series of increasingly distant oceanic islands to encourage exploration. While Fuegians did venture south of Cape Horn to exploit sea lion rookeries, they never discovered the Falkland Islands, which are more of a Madagascar comparable in terms of winds, coastal configurations, and ocean currents (plus much colder waters).

Anyway, the point is, Polynesian ocean exploration was the result of 6,000 years of increasingly sophisticated watercraft, celestial navigation, "safe" strategies of exploration into more and more distant and scattered archipelagos, fine-tuning of a portable economy of domesticates, and a cultural ethos that rewarded successful navigation skills. It is very unlikely that this can develop in unfavourable circumstances, or develop quickly in any context, especially where there is not a "ladder of preadaptation", so to speak.
posted by Rumple at 6:23 PM on July 12 [9 favorites]


NZ geneticists Lisa Matisoo-Smith and Anna Gosling have an accessible piece in The Conversation, which unpacks some of the issues with the new paper.
posted by Rumple at 1:04 PM on July 13 [5 favorites]


That's a great article Rumple, thanks. I appreciate their detailed argument that some of the details of the genetic analysis could be wrong. That's a problem we're seeing with all this new genetics-driven anthropology work. The conclusions are presented so clearly, they hide the fact that all the data is relying on very subtle statistics teasing out very faint signals, often with limited and damaged DNA samples. As the genetics improve some of these results are going to change significantly.
posted by Nelson at 2:50 PM on July 13 [4 favorites]


I just want to thank everyone commenting, this is possibly the most fascinating thread I have ever read and I have like 14 tabs open now to read more!
posted by Eyebrows McGee at 8:39 PM on July 13 [2 favorites]


Yeah, when I read the paper Rumple linked with the point about Ioannidis et al. relying on SNP (single nucleotide polymorphisms) I was all "Ohhhh...."

I've used DNA matching services and come right up against the limits of SNPs. Everybody seems to start off thinking that they'll be able to find relatives with (e.g.) 23andMe, and sometimes they do, but many of us run into two fundamental problems:

1) You come from a group with a genetic bottleneck, so everybody from your ethnic group seems to be related to you; or
2) There aren't enough accumulated results from your ethnic group, so you don't get any useful matches.

To give an example of the first problem, I have an Ashkenazi Jewish relative whose ancestry I know, yea, unto the seventh generation, and yet their results show like twenty pages of third- and fourth-cousins who are actually unrelated. That's because the founding population of Western European Jews was pretty small and it had a high degree of endogamy. There are now lots and lots of Ashkenazi Jews who want to discover their family history because their families were disrupted or massacred and they've signed up with DNA matching services and found that they're Ashkenazi Jews thank you Sherlock.

For examples of the second problem, take pretty much any group poorly represented in the USA/Canadian Middle Class.

Anyway, you see where I'm going with this: Ioannidis' paper relies on weak data signals that may have been further obscured because of weird network signal boosting and founder effects. E.g., there has been a known admixture of Chilean colonist DNA, but only small parts of those genomes probably survive. When they do, though, they're going to be widely spread. So you end up with an unrepresentative collection of SNPs deriving from individuals who may themselves have been unrepresentative of the groups you sampled. I imagine you can get all sorts of weird results, depending purely on chance. It doesn't mean the paper is garbage but I suddenly feel very cautious about it. As the classic line goes,: "more research is needed".
posted by Joe in Australia at 9:13 PM on July 13 [3 favorites]


Particularly when you make strong statements which are derived from the genetic data. For instance, what I had not realised from the original paper but was brought out in Rumple's link was that the reason they speculated that the contact may have been in the Marquesas is that the genetic dating puts the contact at or before any evidence of settlement in the Marquesas so from the genetics you want that contact to happen almost immediately.

The problem with that assumption (that is it unlikely that the voyage to Colombia happened right after initial settlement of the Marquesas) is that we know that Polynesian voyaging was not a gradual process at all. Obviously the dates have uncertainties in them but the current evidence is that 80 to 180 years after settling the Society Islands an absolute explosion of voyaging happened. It is absolutely possible that within a single human lifetime, the Cook Islands, Aotearoa/NZ, Hawai'i, the Tuamotos, the Marquesas, and Rapa Nui were settled. Of course it's also possible that this extended a little longer, but is it possible that a single person would have known all of that to happen in their lifetimes? Just barely it is. It is even possible that a single, particularly well travelled navigator might in their lifetimes have made all those journeys! That's something we'll never know.

So knowing that, there is no particular reason to think that the people who did this would have stopped at the Marquesas for a long time before someone got the idea to go out much farther. In fact, isn't that the most logical time to do it? If no-one has travelled long distance to the West in hundreds of years, it might make sense that there's nothing out there but if you and your people have literally just made a long distance voyage from East to West (and if you know others have made long distance voyages in all kinds of directions within your own lifetime) then of course you're going to want to see what's a little further.
posted by atrazine at 6:23 AM on July 14 [5 favorites]


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