Indigenous South Americans reached islands in the South Pacifmizzzfic some 300 years before Christopher Columbus landed in the Americas, according to new genetic evidence.
New genetic research published today in Nature links indigenous South Americans to Polynesian Islanders. Incredibly, it seems a group from what is today Colombia voyaged to the South Pacific around 1200 ACE, reaching islands thousands of kilometres away. Once there, they mingled with the local Polynesian population, leaving their genetic and possibly cultural legacy behind, according to the new research, co-authored by Stanford University biologist Alexander Ioannidis.
Archaeologists and anthropologists have been wondering about this potential link for decades, but evidence has been limited, inconclusive, and speculative.
While sailing through Polynesia during the 18th century, for example, Captain Cook documented the presence of sweet potatoes on South Pacific islands — a weird finding, given this root vegetable’s origins in South America. Scientists took this as evidence of indigenous South Americans travelling to the Pacific Islands or Polynesians travelling to South America and returning home with their sweet potato stash. This theory was challenged two years ago in a Current Biology study, in which the authors argued that the sweet potato arrived in Polynesia some 100,000 years ago, long before humans ventured to this part of the world.
But there’s other evidence to consider as well, such as traces of Polynesian DNA among members of the Brazilian Botocudos tribe. What’s more, the word for sweet potato in the Polynesian language is “kuumala,” which is extremely close to “kumara,” how the Quechua people of northwestern South America describe it.
There’s also experimental archaeological evidence to consider. In 1947, Norwegian explorer Thor Heyerdahl, along with five daring crewmates, travelled from Peru to the Tuamotu Islands in French Polynesia aboard a large wooden raft called the Kon-Tiki. It took them 101 days to travel the 8,000 km. Pushed by the prevailing westerly trade winds, Heyerdahl showed that it was possible to reach Polynesia from South America on a rudimentary boat. He subsequently argued that Native South Americans migrated to Polynesia, an idea for which he was heavily criticised, as conventional thinking had it that Polynesians were descended from Asian migrants.
So, there’s been interesting — yet undeniably flimsy — evidence. For the new study, the authors strove for more robust data. To that end, they studied the genomes of 807 people from 17 Pacific island populations and 15 Pacific coast Native American groups.
“Through this research, we wanted to reconstruct the ancestral roots that have shaped the diversity of these populations and answer deep, long-standing questions about the potential contact between Native Americans and Pacific Islanders, connecting two of the most understudied regions of the world,” said Andrés Moreno-Estrada, a co-author of the study and a geneticist at Mexico’s National Laboratory of Genomics for Biodiversity, in a press release.
With the help of computers, the authors identified key genetic markers known as identical-by-descent segments. These markers can identify shared common ancestry, pointing to recent mating events among groups. In this case, evidence admixture, or gene flow, among Polynesians and Native South Americans was pinpointed to a single contact event that happened at the turn of the 13th century, likely at some point between 1150 ACE and 1240 ACE.
“We found identical-by-descent segments of Native American ancestry across several Polynesian islands,” explained Ioannidis in the press release. “It was conclusive evidence that there was a single shared contact event.”
Shortly after this contact event, the mixed population then spread to other islands, including Rapa Nui, commonly known as Easter Island, in a migration event that likely happened around 1380 ACE.
Interestingly, the DNA of an indigenous group from present-day Colombia was a close match to the DNA found in Polynesians, pointing to a potential starting point for the voyage.
“These spectacular results have major implications for future discussions concerning early migrations and interactions in Polynesia,” wrote Paul Wallin, an archaeologist at Uppsala University who wasn’t involved in the study, in a related News & Views article. “Rapa Nui itself is not suggested to be the initial point of contact between Polynesians and South Americans, but the admixture identified there is thought to have arisen elsewhere in Polynesia in a population that eventually reached Rapa Nui.”
That “elsewhere” — the setting for the single contact event — could be the Marquesas or Tuamotu Islands of central-eastern Polynesia, according to the new research. That’s a distance close to 7,000 km from Colombia, but as Heyerdahl demonstrated in 1947, such a trek is possible, given the prevailing winds and ocean currents.
The new research shows that Native Americans had a genetic and cultural influence on Polynesians in the immediate pre-Columbian era.
“The paper is significant, not only in its main result — there was human transport from Colombia to Eastern Polynesia — which is a novel intriguing hypothesis, but it is also significant in that it provides a considerable amount of data and explicit methodology to an area of science that is rife with speculation and unsubstantiated pet theories,” Robert Scotland, a professor of systematic botany at the University of Oxford and a co-author of the sweet potato study from 2018, wrote in an email to Gizmodo.
Importantly, the authors cite other explanations for their results, including the possibility that Polynesians reached South America and then returned home after mingling with Native South Americans, or even returning to Polynesia with Native South American individuals.
“The paper by Ioannidis seems to me to be excellent and very convincing work,” Sergio D.J. Pena, a biochemist at the Federal University of Minas Gerais in Brazil, wrote in an email to Gizmodo. “I remember reading Heyedahl’s book Kon-Tiki when I was a child. I was fascinated. I am glad that he has been vindicated.”
Pena, who wasn’t involved in the new work, co-authored the aforementioned study about Brazilian Botocudos tribe members sharing trace DNA with Polynesians.
Scotland was concerned that the new paper only considered modern DNA samples and no fossils or historical samples that could further bolster their main finding.
“Some will question how odd it seems that Colombia was the strongest source, given that several other areas on the South American coast are much closer,” Scotland told Gizmodo. “How robust the results are will be demonstrated over time as more samples are added and the community have opportunity to reflect of the results and re-analyse the data.”
These concerns aside, the new paper offers a truly exciting and provocative result. We tend to think of human populations moving steadily eastward, from Africa to Europe to Asia to North America, during prehistoric times, but this paper points to the reverse, at least in this scenario. That these two groups managed to link up 800 years ago in the middle of the Pacific Ocean is nothing short of astounding.