Papuan is an umbrella term for the various indigenous peoples of New Guinea and neighbouring islands, speakers of the Papuan languages. They are often distinguished ethnically and linguistically from Austronesians, speakers of a language family introduced into New Guinea about three thousand years ago.
In a 2005 study of ASPM gene variants, Mekel-Bobrov et al. found that the Papuan people have among the highest rate of the newly evolved ASPM haplogroup D, at 59.4% occurrence of the approximately 6,000-year-old allele. While it is not yet known exactly what selective advantage is provided by this gene variant, the haplogroup D allele is thought to be positively selected in populations and to confer some substantial advantage that has caused its frequency to rapidly increase.
According to various studies, Papuan people, other Melanesians, and Aboriginal Australians are the only known modern humans whose prehistoric ancestors interbred with the Denisova hominin, with whom they share 3–5% of their genome. It appears that Aboriginal Australians made it to South America, where Denisovian genes can be found today.  In addition to Denisovian genes, Aboriginal Australian skulls and linguistic traits have been found in South America. 
^"About 3% to 5% of the DNA of people from Melanesia (islands in the southwest Pacific Ocean), Australia and New Guinea as well as aboriginal people from the Philippines comes from the Denisovans." Oldest human DNA found in Spain --Elizabeth Landau's interview of Svante Paabo, accessdate=2013-12-10