The origin of Melanesians is generally associated with the first settlement of
Australasia by a lineage dubbed 'Australasians' or 'Australo-Papuans' during the
Initial Upper Paleolithic, which is "ascribed to a population movement with uniform genetic features and material culture" (
Ancient East Eurasians), and sharing deep ancestry with modern
East Asian peoples and other Asia-Pacific groups. It is estimated that people reached
Sahul (the geological continent consisting of Australia and New Guinea) between 50,000 and 37,000 years ago. Rising sea levels separated New Guinea from Australia about 10,000 years ago. Recent genomic studies suggest that Indigenous Australians and Papuans diverged from Eurasians 51,000 to 72,000 years ago, and from each other around 25,000 to 40,000 years ago. Particularly along the north coast of New Guinea and in the islands north and east of New Guinea, the Austronesian people, who had migrated into the area more than 3,000 years ago, It was proposed that, from this area, a very small group of people (speaking an
Austronesian language) departed to the east to become the forebears of the
Polynesian people. The indigenous Melanesian populations are thus often classified into two main groups based on differences in language, culture or genetic ancestry: the
Papuan-speaking and
Austronesian-speaking groups. , 1870s. This Polynesian theory was overturned by a 2010 study, which was based on genome scans and evaluation of more than 800 genetic markers among a wide variety of Pacific peoples. It found that neither Polynesians nor
Micronesians have any genetic relation to Melanesians. Both groups are strongly related genetically to
East Asians, particularly
Taiwanese aborigines, therefore making Polynesians and Micronesians not related to Melanesians. It appeared that, having developed their sailing outrigger canoes, the ancestors of the Polynesians migrated from East Asia, moved through the Melanesian area quickly on their way, and kept going to eastern areas, where they settled. They left little genetic evidence in Melanesia, "and only intermixed to a very modest degree with the indigenous populations there". The study found a high rate of genetic differentiation and diversity among the groups living within the Melanesian islands, with the peoples not only distinguished between the islands, but also by the languages, topography, and size of an island. Such diversity developed over the tens of thousands of years since initial settlement, as well as after the more recent arrival of Polynesian ancestors at the islands. Papuan-speaking groups in particular were found to be the most differentiated, while Austronesian-speaking groups along the coastlines were more intermixed. The Denisovans are considered cousin to the Neanderthals. Both groups are now understood to have migrated out of Africa, with the Neanderthals going into Europe, and the Denisovans heading east about 400,000 years ago. This is based on genetic evidence from a fossil found in
Siberia. The evidence from Melanesia suggests their territory extended into southeast Asia, where ancestors of the Melanesians developed. ==History of classification==