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Culture & Groups Some Polynesians Carry DNA of Ancient Native Americans, New Study Finds

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Children play in the ocean behind Ahu Tongariki on Easter Island.
Credit...Josh Haner/The New York Times
 
Children play in the ocean behind Ahu Tongariki on Easter Island.

July 8, 2020
Sign up for Science Times  Get stories that capture the wonders of nature, the cosmos and the human body. 

About 3,000 years ago, people on the eastern edge of Asia began sailing east, crossing thousands of miles of ocean to reach uninhabited islands. Their descendants, some 2,000 years later, invented the double-hulled canoe to travel even farther east, reaching places like Hawaii and Rapa Nui.

Archaeologists and anthropologists have long debated: Just how far did the Polynesians’ canoes take them? Did they make it all the way to the Americas?

The results of a new study suggest that they did. Today, people on Rapa Nui, also known as Easter Island, and four other Polynesian islands carry small amounts of DNA inherited from people who lived in Colombia about 800 years ago. One explanation: Polynesians came to South America, and then took South Americans onto their boats to voyage back out to sea.

Crossing the Pacific

A genetic study suggests that South Americans from present-day Colombia somehow reached the Marquesas Islands in the 12th century. Traces of their DNA were eventually passed down to people living on Rapa Nui and nearby Polynesian islands.

 

ONE POSSIBLE EXPLANATION

Hawaii

Polynesians reach

South America

before 1150

Marquesas

Islands

SOUTH

AMERICA

Migration from Asia

1500–800 B.C.

Polynesians return

with South Americans

from Colombia

before 1150

Migration into

eastern Polynesia

from 800 B.C.

AUSTRALIA

South American

DNA in Rapa Nui

(Easter Island)

from 1380–present

New

Zealand

Mocha

Island

PACIFIC OCEAN

AN ALTERNATE EXPLANATION

Interbreeding in the

Marquesas Islands

by 1150–1200

SOUTH

AMERICA

Migration from Asia

1500–800 B.C.

South Americans

from Colombia reach

the Marquesas Islands

before 1150

Migration into

eastern Polynesia

from 800 B.C.

Rapa Nui

AUSTRALIA

By Jonathan Corum | Source: Nature

This new report bolsters work that archaeologists and anthropologists have been doing for years. Previous genetic studies had also hinted that people on Rapa Nui had some ancient South American ancestry. But the new study offers a more compelling case because the researchers looked at more than 800 people using a number of sophisticated new statistical tools.

 
“This is the most convincing evidence I’ve seen,” said Lars Fehren-Schmitz, an anthropological geneticist at the University of California, Santa Cruz, who was not involved in the study.
 

The new study emerged from a decade-long project to create a map of the genetic diversity in modern Latin Americans. After Asians crossed the Bering Land Bridge 16,000 years ago, they spread across the Americas, reaching the southern tip of South America by 14,000 years ago.

Since then, the populations of Latin America have gained unique genetic mutations, which have gotten mixed as they interbred. When European colonists brought enslaved Africans to the region, the genetic landscape of Latin America changed yet again.

Andrés Moreno Estrada, a geneticist, and his wife, Karla Sandoval, an anthropologist, have worked with Indigenous populations in Latin America to understand their genetic make-up. Because most genetic studies are based on people of European ancestry, variants that could be medically important to other populations are often overlooked.

Last year, for example, Dr. Estrada, Dr. Sandoval and their colleagues published a study on asthma. They discovered mutations in a gene that put certain groups of Latin Americans at greater risk of developing the disease.

In 2013, Dr. Estrada and Dr. Sandoval started collaborating with Chilean scientists to study Rapa Nui. The island, which lies more than 2,100 miles west of Chile, was annexed by the country in 1888.

Dr. Estrada and Dr. Sandoval traveled to Rapa Nui and met with residents to describe their project. Eighty islanders eventually joined the research, curious to learn about their ancestry.

“They were interested to know if they really belonged to the Polynesian islands,” said Dr. Sandoval, who now works with Dr. Estrada at the National Laboratory of Genomics for Biodiversity in Irapuato, Mexico.

 

In an earlier study on Rapa Nui, led by Anna-Sapfo Malaspinas of the University of Lausanne, researchers analyzed DNA from 27 islanders. They found evidence that the participants had a mixture of Polynesian and Native American ancestry.

Some of their Native American DNA appeared to have been inherited from recent immigrants from Chile. But other pieces were different, suggesting they originated from Native Americans many generations earlier.

To test that finding, Dr. Estrada, Dr. Sandoval and their colleagues compared the DNA of 809 people from Rapa Nui and other Polynesian islands, as well as in countries along the Pacific coast from Mexico to Chile.

The researchers found that most of the people on Rapa Nui had some recent Chilean forebears. From them, they inherited both Native American and European DNA.

But six people had no European ancestry at all. Their Native American ancestry had a different source: the Zenu population of Colombia. The scientists then found some of the same pieces of DNA in people on four other islands in eastern Polynesia.

“When I first saw that, I thought there was something going wrong and we needed to fix what we were doing,” said Alexander Ioannidis, a postdoctoral researcher at Stanford University and a co-author of the study. “So then we dove in deeper. It took awhile to really realize that this was real.”

 

The researchers were then able to estimate how long ago these Native American ancestors lived by measuring the size of the DNA fragments. Stretches of shared DNA get smaller with each passing generation.

The researchers found that all of the Zenu-like stretches of DNA in the Polynesians were roughly the same size. They estimated that they came from Zenu relatives who lived about eight centuries ago.

“It’s quite amazing that they can come up with this evidence for contact between these populations,” Dr. Malaspinas said.

Lisa Matisoo-Smith, a biological anthropologist at the University of Otago in New Zealand who was not involved in the new study, cautioned that the history of Polynesia is so complex that the new results might not reflect it accurately.

“Is it possible? Yes, it certainly is,” she said. But, she added, “I’m not convinced.”

 
Image

Rocks filled with petroglyphs perch dangerously close to an eroding cliff at Orongo.
Credit...Josh Haner/The New York Times
 
Rocks filled with petroglyphs perch dangerously close to an eroding cliff at Orongo.

 

Dr. Matisoo-Smith said the study would have been stronger had the researchers compared the Polynesians with other populations, such as people in mainland China. That would help rule out the possibility that what looks like Native American ancestry in Polynesia is actually just DNA inherited from the common ancestors of the two groups in Asia.

If the research holds up to further scrutiny, many experts said the best explanation would be that Polynesians came to South America and then took South Americans onto their boats to voyage back out to sea.

Dr. Malaspinas said that since Polynesians had already traveled so far across the Pacific, there was no reason to think they couldn’t go to South America. “This last step would have been easy for them,” she said.

Patrick Kirch, a University of Hawaii archaeologist, said that this scenario fit with other lines of evidence, including the food that Polynesians eat.

One important staple across Polynesia is the sweet potato, which originated in South America. Dr. Kirch and his colleagues have found remains of sweet potatoes centuries before Europeans arrived in the Pacific.

 

But the authors of the new paper emphasize another possibility: South Americans traveled on their own to a Polynesian island, where Polynesians sailing from the east encountered them.

Dr. Estrada argued the South Equatorial Current could easily carry boats away from the Pacific Coast of Colombia.

“It happens today,” he said. “We have many stories of fishermen in Mexico who have to get rescued by Japanese fishing boats.”

In their paper, Dr. Estrada and his colleagues draw parallels between this scenario and the claims of Thor Heyerdahl, the Norwegian explorer who sailed on a raft in 1947 from South America to Polynesia. Mr. Heyerdahl championed the idea that Polynesia was settled by South Americans.

In an email, Haunani Kane, a postdoctoral research fellow at the University of Hawaii, criticized the scientists for championing such “outdated” ideas.

 

Dr. Kane has sailed thousands of miles in double-hulled canoes as the scientific coordinator of the Polynesian Navigation Society. She took issue with “the author’s assumption of the capabilities or lack thereof, of Pacific Island peoples to purposely migrate across the Pacific.”

Dr. Kirch also dismissed the castaway scenario. If South Americans wound up on the Marquesas Islands, they would have brought some things with them that archaeologists could have later uncovered. “There’s no evidence of that,” he said.

One way to settle this dispute might be to find DNA in the earliest human remains on islands in eastern Polynesia. A child of Polynesian and South American parents would have a clear genetic signature.

Ancient DNA from South America might help, too. Dr. Fehren-Schmitz has looked for Polynesian DNA in the ancient human remains in the Andes he has studied. “But I’ve never seen any trace,” he said.

It’s possible, Dr. Fehren-Schmitz said, that other places in South America would be better to look for lost Polynesians. It’s conceivable, for example, that some Polynesians who reached South America may have opted to live on the islands just off the coast.

 

One such place is Mocha Island, just off the coast of Chile. In 2010, Dr. Matisoo-Smith and Jose-Miguel Ramirez of the University of Valparaíso published a study on skulls that were unearthed on the island.

The skulls, she said, “looked very Polynesian in shape and form.”

Some Polynesians Carry Native American DNA, Study Finds - The New York Times (nytimes.com)

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South American or Central American Native Americans could have possibly made it to Rapa Nui (Easter Island) on their own during precolonial times or even before the Polynesians arrived to Rapa Nui, but it's just less likely.  The idea that some lost group of Native Americans were swept to Rapa Nui is possible, but very improbable given the distance and size of Rapa Nui which is small at 63.2 square miles (163.6 square kilometers).  Rapa Nui is 2,182 miles to the closes point in Chile (and the closest point to the Americas in general).  Have you ever heard of a land or island especially of this distance and size being settled this way?  The distance not only makes it less probable to accidentally stumble upon Rapa Nui, but surviving for that long is very improbable.  These hypothetical lost survivors did not likely have the original intention of being out on sea for a long time as they were likely fishermen carrying a very small amount of food rations and fresh water.  Also, most fishing expeditions from the Americas would likely have consisted of males.  Native Americans were not transoceanic seafarers from what I know.  They did colonize the islands very near the continent and the Caribbean Sea.  But many islands beyond a hundred miles outside the continent were uninhabited such as the Galapagos Islands in the Pacific (the closest point from the Galapagos Islands to the Americas is in Ecuador with a distance of 575 miles or 926 kilometers).  The Juan Fernandez Islands (an island chain consisting of 3 islands in the Pacific about 416 miles (669.4 kilometers) from the nearest point of the Americas which is in Chile were also uninhabited prior to colonial times.  They all have a subtropical climate with a precolonial seal population in excess of 4 million, so there was a good climate and a lot of food for anyone wanting to settle there.  Alejandro Selkirk Island is the largest of them at 19.1 square miles (49.5 square kilometers).  Robinson Crusoe Island has an area of 18.51 square miles (47.94 square kilometers).  Santa Clara Island is very small at 0.85 square miles (2.2 square kilometers) and is uninhabited today.  Both Alejandro Selkirk Island and Robinson Crusoe Island are good size islands that could have easily supported human populations.  Guadalupe Island in the Pacific is about 248.5 miles (400 kilometers) from Mexico was also uninhabited during precolonial times.  It has an area of 94.2 square miles (243.9 square kilometers) with a warm climate that could easily support human population.  The Revillagigedo Islands in the Pacific are a group of four islands about 285 miles (458 kilometers) from Mexico, and they are all in the tropical zone with a total area of 60.93 square miles (157.81 square kilometers).  Socorro Island is by far the largest of this island group at 51 square miles (132 square kilometers); Clarion Island comes in at second at 7.6 square miles (19.8 square kilometers); San Benedicto Island comes in at third at 2.29 square miles (5.94 square kilometers).  Roca Partida is a very small islet.  The Revillagigedo Islands could have supported human population fairly easily. 

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A couple more Eastern Pacific islands in the tropical zone that are of significant size are Cocos Island at 9.21 sq mi (23.85 sq km) and at a distance of 342 mi (550 km) from Costa Rica, and Clipperton Island at 3.4 sq mi (8.9 sq mi) and at a distance of 671.08 mi (1,080 km) from Mexico.  Both these islands could have supported human populations during precolonial times but are thought to be uninhabited until the colonial period. 

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The Aleutian Islands were the only islands in the Pacific that protruded well into the Pacific (as they are a string of islands) from the Americas that Native American Indians, namely Aleuts, colonized although the islands might be considered part of the continental shelf, and are probably not true oceanic islands.  It should be mentioned that probably 10,000 to 20,000 years ago or more, the Aleutian Islands were a land bridge for the earliest humans migrating from Asia into the Americas when the sea levels were far lower.  The Aleuts may have arrived much later, and possibly when the sea levels were close to its present level thus the migration of the Aleuts onto the islands required a seafaring tradition that continues to this day.  

 

 

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Most likely Native Americans traveled by sea within the North and South American continental shelves with the exception of the Caribbean Sea and nearby islands.  Despite these limitations Native Americans have a great watercraft tradition.  Just like any group in this world, they adapted to their environment and geography. 

The kayaks of the Inuits and Aleuts were made of materials found in the Arctic, Subarctic, and Aleutian Islands, are fast moving, light, and maneuverable to deal with floating ice, ice bergs, rapids, and easy portage over land.  The kayak is the only watercraft that I know of that you can perform a kayak roll or Eskimo roll.  The kayak essentially allows you to right yourself up after being capsized and some can do it without getting wet at all or the kayak having to take in any water by wearing a specific suit.  The double bladed paddles of the Inuits and Aleuts were also a very efficient way to paddle.   

The Chumash, Tongva/Kizh, and Acjachemen of Southern California would take their tomols and te'aat respectively into the Channel Islands off the coast Southern California.  Like the Inuits and Aleuts, the Chumash, Tongvas, and Acjachemen used a double bladed paddle (they may have been influenced by the Inuits and Aleuts), but their paddles were longer to accommodate for the ships they used.  Some say their boats were influenced by Polynesians as they are made of wooden planks sewn together and waterproof using a caulking (hard tar, pine pitch, and other sealants) since many Polynesians use a similar boat making technique, but this is disputed.  These Southern California seafarers would paddle several miles into the Channel Islands without the use of sails, the furthest of which (San Nicolas Island) is about 61 miles from the mainland.  

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