At http://popular-archaeology.com/issue/fall-2017/article/huge-genetic-dive… … a huge amount of genetic diversity has been found between different groups and tribes in New Guinea which seems to reflect the length of the period they have been living on the island. This matches the equally diverse number of languages and sub languages spoken on the island – 850 in number. Not only is Papua New Guinea diverse but there is also big differences between people living in the highland zone and those living in the lowlands and along the coastlines. In the highlands zone some of these people have been isolated for between 10 and 20,000 years, much longer than in any other region of the world. It is also probably true that New Guinea has been fairly isolated for 50,000 years – or longer (from the evidence of language and genes). No doubt immigrants washed up along the coast on occasion, such as the proto Polynesians, but the interior of the country remained free of admixture – and this is reflected in the differences between New Guinea people and those in what is now Indonesia. The Wallace Line is projected as the great divider – but at one time people must have moved through Sunda Land in order to reach New Guinea and Australia – or did they island hop through Melanesia (or is there a possibility the coastline of east Asia differed considerably in the past).
The study is published in the journal Science (Sept 15th 2017). The lead author is Anders Bergstrom and the second author is Stephen Oppenheimer of Oxford University, author of a number of books on DNA studies and ancient population movements.