Melanesian Genetics Among Most Diverse

Jan. 23, 2008 -- An extensive new study on Pacific Islanders has determined that Polynesians and Micronesians bear little genetic relationship to Melanesians, who turn out to be among the most genetically diverse people on the planet.

In addition to revealing how these people are, or aren't, related to each other, the new study, published in the current PLoS Genetics, indicates the origins of the native island inhabitants and how the regions were initially settled.

Polynesia includes Hawaii, Easter Island, New Zealand and certain other south central and eastern Pacific islands, while Micronesia refers to small islands, such as Guam, that are in the central Pacific north of the equator. Melanesia includes Fiji, New Guinea, and other islands in the chain north and east of Australia.

"The first people to enter the Pacific came from Southeast Asia, along the stepping-stone island chain -- now Indonesia -- to ancient Australia and New Guinea, and to the nearby islands just to the east and southeast, the Bismarcks and the Solomons," lead author Jonathan Friedlaender told Discovery News.

"They got there between 50,000 and 30,000 years ago, when Neanderthals were still roaming Europe -- very, very early in modern human prehistory," added Friedlaender, who is professor emeritus of anthropology at Temple University.

Melanesia was also settled around this time, probably by individuals from East Asia. Although Melanesians today resemble certain African groups, they turn out to be genetically far removed from Africa.

Friedlaender and his international team looked at 800 genetic markers known as microsatellites. Also called "junk DNA," these markers can vary a lot between individuals. One person might have a GAGAGAGA code, for example, while another could just have GAGAGA.

"Since they vary a great deal between individuals in how many repeated segments they have, they can tell a great deal about a person's identity and history," Friedlander said, adding that junk DNA is commonly used in forensic cases as a result of its individual uniqueness.

The latest genetic data supports a version of what has been called the "fast train hypothesis" concerning Pacific Island settlements. In this scenario, the Polynesians are the train. They traveled everywhere in the Pacific, without leaving much of a genetic fingerprint.