Native Hawaiians and Rapa Nui people on Easter Island are genetically descended from the same group of Polynesian “supernavigators” who crossed vast stretches of the Pacific, according to a new study. By comparing the genomes of 1,050 people from across Polynesia, researchers reconstructed connections between islands separated by thousands of miles and identified genetic bottlenecks that continue to influence Polynesian health today.
Easter Island, also known as Rapa Nui, and Hawaii are part of Polynesia, a region of more than 1,000 islands spread across an area of the Pacific Ocean roughly equal in size to North and South America combined. They are the two most distant islands in the region, approximately 4,500 miles (7,200 kilometers) apart — about the distance from San Francisco to Lima, Peru.
Tracing a shared Polynesian ancestry
The researchers analyzed modern genomes from across Polynesia, including 317 Native Hawaiians and 12 Rapa Nui people. “Each person’s genome contains genetic code from their parents, all four grandparents and their parents, and more,” study co-author Alexander Ioannidis, a computational geneticist at Stanford University, told Live Science. “Each genome encodes a huge number of ancestors, so even a small number of individuals can tell us about a huge number of people on each island.”
The scientists compared the lengths of chromosome segments shared by people from different islands. Longer shared segments generally indicate that two people have a more recent common ancestor, allowing researchers to estimate when populations were connected.
Despite the great distance between Hawaii and Easter Island, the analysis found that Native Hawaiians and Rapa Nui are each other’s closest genetic relatives among the Polynesian populations examined. The research team reported its findings on October 8 in the journal Science.
“It was really shocking at first, these islands are so far apart from each other,” Ioannidis said.
The findings indicate that both islands were likely settled by members of a single seafaring culture from the region around the Mangareva Islands. Mangareva lies about 3,440 miles (5,530 kilometers) southeast of Hawaii and 1,600 miles (2,600 kilometers) west of Easter Island.
In 2020, researchers found evidence that members of this long-distance voyaging group interacted with Indigenous peoples in what is now Colombia. However, it remains unclear whether that interaction occurred on an island or on the South American continent.
“Knowing that there was a very capable long-range supernautical culture that could reach one of these islands, it makes more sense to have it reach the other island,” Ioannidis said.
The region around Mangareva, including the Austral, Society, Marquesas and Tuamotu islands, covers an area “the size of Europe,” Ioannidis said. Traveling between these islands would have required advanced navigation skills, he added, making it plausible that techniques developed for those journeys eventually enabled people to settle Hawaii and Easter Island.
Overall, the genetic evidence suggests that the ancestors of Native Hawaiians and Rapa Nui people spent time together as a common population after separating from an ancient Mangareva population. Some members of that group later settled Hawaii, while others sailed to Easter Island.
This genetic connection is “very consistent with what we see archaeologically,” Patrick Kirch, an archaeologist at the University of Hawaiʻi at Mānoa who was not involved in the study, told Live Science. “Scientists can gain great confidence when independent bodies of evidence from different fields yield similar results.”
Repeated founder effects
The researchers also examined genetic bottlenecks that occur when a small number of people establish a new population. This phenomenon is known as the “founder effect.”
When a rare inherited trait happens to be present among the founders, it can become relatively common as the small population grows. “This means that a rare genetic mutation that once affected only a few people may now start to affect a significant number of people,” Ioannidis said.
The Indigenous Polynesian populations in the study often experienced multiple founder effects over time. Islands settled by small groups subsequently sent out new groups to establish settlements elsewhere, creating additional bottlenecks in the descendant populations.
Founder effects have also been documented in populations of European descent, including the Amish, Finnish people and Ashkenazi Jews. Such effects can help explain why particular genetic conditions are more common in those groups and why targeted screening may be useful.
The study found an even stronger founder effect among Native Hawaiians than among the European populations examined — more than 10 times stronger, according to the researchers.
“Founder effects reflect not only genetic diversity, but also cultural and linguistic diversity,” Kirch said. “This probably helps explain why the cultures of eastern Polynesia all have something in common. They all trace back to one central group.”
Potential health implications
The results also provide information about the present-day health of Polynesian populations. Between 2% and 3% of the Eastern Polynesians included in the study carried three genetic mutations that are extremely rare worldwide. The mutations are associated with dislocation of the eye’s lens, progressive vision loss and kidney failure.
“More resources should be devoted to learning more about potentially clinically important genetic variants in this Native Hawaiian population, which is twice the size of the Amish population in the United States,” Ioannidis said. “There is a real opportunity here for precision health.”
The study is: Shanks, C., Huang, E.C., Thomasin, C., Emde, A., Rodière, V., Moraga, M., Sandoval, K., Merriman, T., Pascart, T., Moreno-Estrada, A., Castel, S.E., Fox, K. and Ioannidis, A.G. (2026). “Messages at bottlenecks: Nested founder effects from French Polynesia to Rapa Nui to Hawaii.” Science, 394(6820), 216–221.
Source: www.livescience.com