What do we now really know about the ancient settlement of the Pacific?
First of all it's important to understand what the archaeologists have outlined for the ancient settlement of the Pacific. It's pretty clear that the first humans who got to Australia and New Guinea and the islands immediately to the east were some of the very early humans to get out of Africa. This is about 40,000 years ago, when Neanderthals still occupied Europe. And so this region of the Pacific—New Guinea and the small islands to the east—is called Near Oceania. People were in relative isolation after that period for the next 35,000 years, which is pretty incredible. Then there was clearly a second phase of migration by humans about 3,300 years ago, coming out of Asia, and there's a distinctive pottery style that appears called Lapita. These are supposed to be the ancestors of the Polynesians and Micronesians, and they settled the islands that were at that time uninhabited out into the middle of the Pacific. What genetics can contribute to this prehistory is knowing how people interacted—the sort of race intermixture that happened during these intervals. For example, we can tell that there's some really, really old mutations that occurred and are limited to this part of the Pacific—that is, New Guinea and the islands just to the east as well as Australia.
What has genetics contributed to this picture?
Up until this point we've had two kinds of genetic evidence that have been in semiagreement on some of these things. First is the Y chromosome, which is inherited through males, and the second is mitochondria DNA, which is inherited just through females. So while they're in general agreement about these sort of early and very late migrations into the area, there's some disagreement between the two lines of genetic evidence about the composition of the Polynesians—how much Melanesian influence there was, and how much Asiatic influence they retained. And that's where some of these old notions of "fast train out of Taiwan," which is supported by the mitochondrial evidence, versus sort of the slow boat that picked up a lot of Melanesia immigrants, which is supported by the Y chromosome, have gotten involved. But I think we really have to realize that in the end it's the archaeology that gives us the real time frame for all this stuff.
So, what do your new genetic studies suggest about all this?
What our new genetic data, from hundreds of different gene markers inherited from both the fathers and the mothers, show very clearly is that the Polynesians and the Micronesians are really closely related to Taiwan aborigines and East Asians who have very little to do in terms of intermixture with the Melanesians as they passed through that area. And this was quite a surprise, frankly. We know there was a lot of cultural and linguistic interchange between the peoples as they interacted in these islands, but not much in the way of genes, apparently. So, I think if you have to talk about trains and boats and metaphors like that, I think that the archaeology says it was a pretty fast train that originated in the Taiwan vicinity, and our data suggests that there were very few passengers who got on or off on the way through. The other thing to say is that our work really comes down and shows how incredibly differentiated the different Melanesia populations are one from another, and this is something people tend to overlook.