A genetic study shows how humans spread to the islands of Polynesia. Some islands in the Pacific Ocean are thousands of miles away.
Alexander Ionidis, an assistant professor of artificial intelligence at Stanford University, and his colleagues graphically analyzed the DNA of 430 Polynesian descendants.
Polynesia is made up of about a thousand islands covering one third of the world. This includes New Zealand, Hawaii, Easter Island and Samoa.
The prevailing opinion is that the people of Asia reached the island of Samoa about 3,000 years ago. These people probably used double hull canoes. After this they spread to other islands in the Pacific.
“We had a general idea of how the Polynesian islands were populated,” says Ionitis. “But this is the first study to provide a more comprehensive picture.”
Researchers explored the sequence in which the Polynesians discovered the islands. They did it using a genetic phenomenon called the founder effect. In addition, there is less genetic variation in the population if it initially has some members. This can happen if a small number of people settle on an island. If a small group of these people migrates to the Second Island, the Second Founder effect occurs. This again reduces genetic variation in a small but measurable way. With each subsequent step, a subtle effect can be observed.
By comparing the genetic variation in the DNA of subjects on all islands, the team was able to determine where people came from and in what order they crossed the islands. According to researchers, the first voyage was 1,550 km from Samoa to the Cook Islands in 830 BC.
The team determined the migration time more specifically by comparing some of the DNA sequences of the subjects. If two Polynesians on different islands have some similarities in their DNA, it means they have a common ancestor.
“With each generation that comes after that ancestor, this shared DNA gets smaller and smaller,” says Ionitis. The smaller the shared DNA, the more time has passed since that ancestor lived. That way we get a good idea of when that ancestor settled on a new island.
Researchers have discovered that the Polynesians had Easter Island as one of the last islands of 1100. The population of the island, which is known for its mysterious stone carvings, is closely related to the population of the Marquesas Archipelago, 2,500 miles (3,500 km) from Easter Island, and the Rivaway Islands.
All of those islands or archipelagos have statues not found anywhere else in Polynesia. Genetic analysis says that the same statue built all the statues. “We still don’t know why they built those statues, but we know that these heroic travelers were the creators,” says Ionidis.
These findings tap into earlier research that Polynesians were in contact with Native Americans at this time.
“It is important to understand the history of Eastern Polynesia because the people in this region were the last to be populated,” said Casimo Post, an archaeologist at the University of Dubingen in Germany. “This new study paints a very detailed picture of the sequence and direction of those early journeys.”