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The map of Austronesian expansion across the Asia-Pacific looks very peculiar:

enter image description here

The Austronesians colonized all major islands of the Indonesian archipelago, and almost all of the habitable islands of the southern Pacific (major and minor), but very curiously did not colonize New Guinea—despite its intermediate location and vast natural resource wealth.

This old History Stack discussion explains why Australia was not colonized by Austronesians, with the main reasons being A) warfare against aboriginals, B) opposition to interacting with other cultures, C) trade winds pushing away from Oceania, and D) hostile terrain and climate. I don't think any of these explanations make sense for New Guinea.

A) Why was warfare against Indonesian aboriginals not a roadblock? Indonesia was inhabited by "Negrito/Australo-Melanesian" hunter-gatherers (according to Wikipedia) before they were displaced by Austronesians. Were Papuans somehow more effective at fighting Austronesians?

B) Again, if Austronesians were willing to interact with (or kill, I suppose) aboriginal Indonesians, why weren't they willing to interact with Papuans?

C) Why didn't hostile trade winds prevent Polynesians from colonizing the Pacific islands?

D) New Guinea's terrain and climate are very similar to that of Indonesia and quite different from that of arid-desert Australia.

There was some Austronesian settlement on the northern coast, but it was extremely minor compared to the colonization of the rest of the Indonesian archipelago, as suggested by the map. This remarkable study finds that ~99% of the genetic ancestry of Papua New Guinea is Papuan (~1% Austronesian), whereas ~99% of the genetic ancestry of western Indonesia is Austronesian (~1% Papuan). Eastern Indonesia is more mixed, but still largely Austronesian.

Our analyses, thus, refute suggestions that the Asian ancestry observed in Indonesia largely predates the Austronesian expansion (2, 27), or that the Austronesian expansion was not accompanied by large-scale population movement (4). To be sure, other migrations (both before and after the Austronesian expansion) have undoubtedly left a genetic legacy in Indonesia. However, our analyses of genome-wide data do indicate that there was a strong and significant genetic impact associated with the Austronesian expansion in Indonesia, just as similar analyses have pointed to a genetic impact associated with the Austronesian expansion through Near and Remote Oceania (24, 28).

So, why didn't Austronesians colonize New Guinea?

Kate Gregory
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StarlightDown
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  • Exception made of Madagascar and New Zeland, the Austronesians seemed to have avoided the big islands. Maybe an explanation? Also, considering the land is closed, they might have considered it was already inhabited and not a good place for them, compared to unknown and "idealized" farther lands? – totalMongot May 01 '23 at 09:19
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    Good point. Although they did colonize Borneo, which is a similar size. – StarlightDown May 01 '23 at 09:28
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    The first thing I'd look at is the state of the shoreline. How favorable is it to the Austronesian way of life? (Foods, stable land, access to/from boats?) The little I know of New Guinea's shore is that it's pretty swampy, which they may not have found to be attractive. – Mark Olson May 01 '23 at 12:35
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    @StarlightDown You're right Borneo is a counterexample to my "theory". – totalMongot May 01 '23 at 14:56
  • Topographic map of SE Asia: https://pixelsmerch.com/featured/southeast-asia-topographic-map-horizontal-3d-render-color-frank-ramspott.html. New Guinea's northern shoreline seems to be more mountainous than most other Indonesian islands, though not as mountainous as the Sulawesi coast, which was colonized early and extensively. Southern shoreline looks mostly flat, but possibly swampy. Good catch, this could be a candidate explanation. – StarlightDown May 01 '23 at 15:38
  • Wasn't this answered in Guns, Germs, & Steel? – T.E.D. May 04 '23 at 12:58
  • This is wild speculation but the biogeographical Wallace Line -- separating evolutionary speciation on one side from the other -- runs through the Indonesian archipelago. Is the answer to your question a variant of that line? https://en.wikipedia.org/wiki/Wallace_Line –  May 05 '23 at 11:42
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    @DJohnson, that was one thought I had. Maybe the ecology of the island couldn't support Austronesian settlement and/or agriculture. Though it seems to more closely follow the Lydekker Line. – StarlightDown May 05 '23 at 13:26

1 Answers1

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I think the vital piece of information you were missing that made this appear to be a mystery was that, unlike a lot of the rest of Indonesia, the native inhabitants of New Guinea that the Austronesians found living there were not a thin population of hunter-gatherers. Rather the Paupuans of the interior were one of the world's densely populated agricultural societies. In fact, the island highlands were one of the many worldwide independent loci of the discovery of agriculture when the current interglacial started around 10,000 years ago.

enter image description here

The Austronesians would have reached the shores of New Guinea around 1300BC. McEvedy & Jones estimate there were probably around a quarter of a million Paupans living there at that time. That isn't a lot by today's standards (currently the island supports on the order of 40x that), but was a very respectable number at the time, and clearly far more than a few boatloads of Austronesians were capable of wiping out. Austronesian farming techniques weren't significantly better, they weren't more organized, and once you got inland a bit past the reach of their boats, the military logistics weren't in their favor.

enter image description here

That doesn't mean they had 0 impact though. There are in fact today widespread Austronesian-speaking enclaves near the coasts (where one would expect to see them), circumstantially the Austronesians clearly went through the area, and ongoing trade with their society is one reasonable explanation of how the South American domesticated Sweet Potato got added to the Paupuan crop package (if indeed that happened pre-Magellan).

enter image description here (A good map of the Asmat-Kamrau (Paupuan) language distribution, useful here as it also shows the actually somewhat extensive distribution of Austronesian languages in New Guinea)

T.E.D.
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  • Great answer. Although I do wonder why the regions of New Guinea which did not adopt agriculture were not colonized. "It has long been supposed that New Guinea is a land of cultivators. However, a close examination of the ethnographic record has revealed numerous references to the presence of 'hunters and gatherers.' The record suggests, in fact, that some 10-20 New Guinea societies were almost entirely dependent on wild foods at contact; another 20 or so procured at least 90% of their calories by foraging." https://www2.umaine.edu/climatechange/Research/projects/NewGuinea.html – StarlightDown May 05 '23 at 13:43
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    @StarlightDown - New Guinea is home to a lot of biomes. Its like an entire continent packed into one island. Most of the agriculture there has traditionally been carried out in the interior highlands. A good crop plant doesn't grow just anywhere. – T.E.D. May 05 '23 at 14:12
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    Another good example of the continent-in-an-island principle: There are estimated to be about 6.5k languages in the world. Nearly 1,000 of them, more than 1 in every 8 in existence, are found on New Guinea. – T.E.D. May 05 '23 at 14:16
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    @StarlightDown - But as you can see from that last map, the Austronesians did colonize where they could. In terms of real-estate, that language family is arguably spoken over more of the island than any other ("Paupan" isn't really a proper "genetic" language family, just an "areal grouping", or an adjective describing where they are). – T.E.D. May 05 '23 at 14:22