An interesting video about the linguistic history of New Guinea and what it reveals about the past of the people of the island.
The first inhabitants Indigenous people of New Guinea, from whom the Papuan people are probably descended, adapted to the range of ecologies and, in time, developed one of the earliest known agricultures. Remains of this agricultural system, in the form of ancient irrigation systems in the highlands of Papua New Guinea, are being studied by archaeologists. Research indicates that the highlands were an early and independent center of agriculture, with evidence of irrigation going back at least 10,000 years. Sugarcane was cultivated in New Guinea around 6000 BCE.
The gardens of the New Guinea Highlands are ancient, intensive permacultures, adapted to high population densities, very high rainfalls (as high as 10,000 mm per year (400 in/yr)), earthquakes, hilly land, and occasional frost. Complex mulches, crop rotations and tillages are used in rotation on terraces with complex irrigation systems. Western agronomists still do not understand all of the practices, and it has been noted that native gardeners are as, or even more, successful than most scientific farmers in raising certain crops. There is evidence that New Guinea gardeners invented crop rotation well before western Europeans. A unique feature of New Guinea permaculture is the silviculture of Casuarina oligodon, a tall, sturdy native ironwood tree, suited to use for timber and fuel, with root nodules that fix nitrogen. Pollen studies show that it was adopted during an ancient period of extreme deforestation.
In more recent millennia, another wave of people arrived on the shores of New Guinea. These were the Austronesian people, who had spread down from Taiwan, through the South-east Asian archipelago, colonising many of the islands on the way. The Austronesian people had technology and skills extremely well adapted to ocean voyaging and Austronesian language speaking people are present along much of the coastal areas and islands of New Guinea. They also introduced pigs and dogs. These Austronesian migrants are considered the ancestors of most people in insular Southeast Asia, from Sumatra and Java to Borneo and Sulawesi, as well as coastal new Guinea.