I read an article about recent upheaval in Melanesia, specifically, that the people of Bougainville are ethnically closer to the people of the Solomon Islands, than they are to the people of Papua New Guinea. The people of Papua New Guinea are a 99% match to the Iberian Roma, and both are in turn very closely related to Heidelbergensis. See Section 6.1 of A New Model of Computational Genomics [1]. This sounds superficially implausible, but the Roma are from India, and so it’s perfectly sensible that many of them settled in Papua New Guinea.
I thought I would look into the genetics of the people of the Solomon Islands, and I found this genome in the NIH Database. It turns out the maternal line of this Solomon Island individual is completely different from that of the people of Papua New Guinea, and in fact, the individual doesn’t match to a single genome from Papua New Guinea. These are completely different people, despite superficial similarities.

Above is a chart that shows the distribution of 99% matches by population for the Solomon Islands genome. The x-axis shows the population acronym (you can find the full population name at the end of [1]), and the y-axis shows the percentage of the population in question that is a 99% match to the Solomon Islands genome. You can plainly see that this individual is closely related to many Mexicans and Hungarians. This is a truly complex world, and our notions of race are just garbage. You can find the software to build this graph in [1], and there are links to the full mtDNA dataset as well.