An international team of scientists has discovered that residents of the remote equatorial islands of Melanesia share fragments of genetic code with two extinct human species.
The researchers compared the DNA sequences of 35 modern people living on islands off the coast of New Guinea with DNA drawn from two early human species: Denisovans, whose remains were found in Siberia, and Neanderthals, first discovered in Germany.
"Substantial amounts of Neanderthal and Denisovan DNA can now be robustly identified in the genomes of present-day Melanesians, allowing new insights into human evolutionary history," the study said.
"As genome-scale data from worldwide populations continues to accumulate, a nearly complete catalog of surviving archaic lineages may soon be within reach," the study noted.
The findings were published in the journal Science.
Th researchers collected the modern-day blood samples used in the study about 15 years ago in Melanesia. This is the first time full genomes from those samples have been sequenced.
"I'm surprised that these Neanderthal and Denisovan genomes made it out to this remote place," said one of the researchers Andrew Merriwether, molecular anthropologist at Binghamton University in New York.
"We know people have been there for at least 48,000 years because we find human remains that go back that far, but no one has ever been able to connect them to any other place. When you compare most of their genome sequences, they don't cluster with any other group. They've been there and been isolated for a very, very long time," Merriwether noted.
Studies like this one may enable scientists to answer big questions about human migrations and evolution thousands of years ago.
How did ancient humans travel -- and cross the ocean -- to get to Melanesia, and when and where did the Denisovan DNA enter our gene pool?
The researchers believe that sequencing of additional DNA samples found in Asia may one day help to answer those questions.
