Hawaii is one of the most isolated islands on Earth, surrounded by vast oceans for thousands of miles on every side. And yet humans have been living there for nearly a millennia. They’re part of the Polynesian diaspora.
This culture of ultravoyagers embarked on their own age of exploration while Europe was still mired in the Middle Ages, colonizing the tiny islands dotting the South Pacific without the benefit of metal tools, navigational equipment, or a written language. Now, a new study published in Science Advances is better defining their genetic history. Previous genetic research conducted by the team allowed them to look even further back in time, retracing the path of the diaspora that eventually wound up in Hawaii.
Polynesian peoples spread to Fiji and Tonga, then pushed east to the Cook Islands, Tahiti, and Mangareva. They settled on Easter Island in the early 1200s, but they didn’t stop there. According to the team, generations of island-hopping left their mark on the genomes of these ultravoyagers, especially the Native Hawaiians at the end of the line.
When a smaller subsection of a population settles in a new place, the founders of the new colony only carry a fraction of the population’s gene pool. The result is a genetic bottleneck (called the founder’s effect) that can magnify the frequency of previously rare genes in the following generations, turning uncommon alleles into common ones. The team determined that founding populations grew rapidly following settlement, preventing the new gene pool from being swamped by future migration.
Additionally, because the genomes of Native Hawaiians passed through chains of these bottlenecks en route to their final destination, it compounded the founder’s effects. The team identified three deleterious alleles that occur at a slightly higher frequency (between 2-4 percent), which cause conditions like dislocated lens in the eyes, vision loss, and kidney failure. According to the researchers, it’s a problem that needs to be addressed.
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