Racial migrations and human genetics: The “game changer” in the South Pacific that wasn’t – part 3

John Edward Terrell and Kevin M. Kelly

This is part 3 of a 3 part commentary

How many immigrants does it take to make a migration?

When presented with a sample comprising only 3+1 skulls, both scientific caution and parsimony suggest you should assume that colonists coming ashore back at the beginning of human history in Vanuatu and Tonga were probably more diverse, biologically speaking, than is witnessed by these four—at least until there is further evidence showing they did indeed come not just from a genetically homogeneous place of origin, but also a place where the inhabitants were as sui generis as they appear to be vis-à-vis others on earth (Skoglund et al. 2016: fig. 1b).

Logic such as this is well worth attending to. But in this instance, there is an equally logical way to get around the usual working assumption that people are likely to be more diverse than first appearances may suggest. Given how poorly specified are the two hypotheses under scrutiny here, it is anyone’s guess how big  we are supposed to think the boats must have been that brought early colonists to Vanuatu and Tonga around three thousand years ago. Even granting they may have arrived in more than one canoe, it would be reasonable to assume those arriving were fairly few in numbers. If so, then there is no need to assume blindly that those who came ashore in Vanuatu or Tonga constituted a representative (random) sample of the real human genetic diversity among those back home in the places where they came from, wherever on earth that was (Terrell 1986).

Furthermore, this is not all that might be reasonably assumed when trying to pin down the who, what, where, why, and when behind these four skulls. The number of pioneering colonists arriving  in canoes from elsewhere with them or before them may not only have been relatively few. They may also have been kin, i.e., biologically related to one another. If so, then possibly what makes these crania look sui generis in comparison with other people on earth, living and dead, may just be that we are seeing a “family resemblance” in these human remains (Terrell 1986; Walker and Hill 2014).

“Figure 1 New Guinea’s place in the southwestern Pacific (bathymetry downloaded from http://ingrid.ldeo.columbia.edu/SOURCES/ .WORLDBATH/.bath/based on the ETOPO5 5 · 5 min Navy data base).” Source: Terrell 2006: fig. 1
Homeward bound

For journalists and others, the real mystery of these remains, of course, is where these pioneers or their immediate forebears sailed from when they launched their boats to start a new life elsewhere. What is now known or can be reasonably assumed, therefore, about places to the west where they may have sailed from?

Until the Holocene stabilization of sea levels in the southwestern Pacific around 8,000–6,000 years ago, it is likely that much of the northern coastline of New Guinea was steep and uninviting of human settlement (as much of it still is today) except perhaps where favorable local circumstances may have at least temporarily trapped sediment in sandbars, coastal lagoons, and small river deltas. Little is currently known archaeologically about this coastline, which runs east-west for roughly 1,500 miles (2,400 km), and which would logically have been the most likely route between Asia and the farther reaches of the Pacific (Golitko et al. 2016). The best guess at the moment is that few people lived along this coast for the first 35,000–45,000 years of human history in the Pacific (Terrell 2006). In effect, earth and sea conspired to isolate New Guinea, like a sleeping giant, from frequent contact with islanders elsewhere both to the east in what is now popularly called Melanesia, and to the west in Island Southeast Asia (for biological support for this inference, see: Matisoo-Smith 2016: 391).

Following the Holocene stabilization of sea levels, however, coastal areas in Southeast Asia and the Pacific began to develop into rich floodplains, river deltas, and lagoons. By the mid Holocene, it is probable that people in the island realms to the east and west of New Guinea began to deal with one another back-and-forth more often as coastal people began to travel with greater reach along this immense island’s lengthy northern coastline (Torrence and Swadling 2008).

West meets East

Contrary to the notion that there are only two hypotheses about the prehistoric human settlement of the more remote islands in the Pacific east of New Guinea, there are numerous variants not only of those two old ideas but of others, too (for a recent review, see: Matisoo‐Smith 2016). Here we will introduce only one plausible reconstruction (Terrell, in press).

Initial baseline assumptions
  • Archaeologists now think people have been living in Southeast Asia for 50,000 years or so, and perhaps for not quite so long in the islands just east of New Guinea as far as Bougainville in the Northern Solomons.
  • The gradual flooding of the Sunda paleocontinent in what is now Southeast Asia since the Last Glacial Maximum ~21,000 years ago created extensive coastal environments that were ecologically rich and productive (Sathiamurthy and Voris 2006; Hanebuth et al. 2011: fig. 2). Similar extensive flooding did not occur in the area east of New Guinea labeled as Parkinson’s Islands (after the early ethnologist Richard Parkinson) on the map above (Lavery et al. 2016).
  • Due to this environmental advantage, it is probable that there were far more people living in Southeast Asia 6,000 years ago than there were in Parkinson’s Islands.
  • By the mid Holocene—contrary to the prevailing assumption in historical linguistics that doesn’t take this ecological advantage into consideration—it is probable that languages classifiable as Austronesian were widely spoken throughout Wallacea and elsewhere in Southeast Asia even as far north as Taiwan. But not yet in Parkinson’s Islands which had been isolated from Asia by the island of New Guinea.
  • Throughout the Late Pleistocene and early Holocene, Wallacea and Parkinson’s Islands were both areas of the Pacific where the advantages of travel by sea rather than by land nurtured the use of canoes and the development of local navigational methods and skills.
  • Canoes equipped with outriggers and sails were invented in Southeast Asia at some point in the Late Pleistocene or early Holocene. Simple dugout canoes remained the predominant boat type used for travel among coastal communities in Parkinson’s Islands.
Illustration taken from Labillardiere, (1800). Atlas pour servir a la relation du voyage de la recherche de la Perouse. Page Plate 43. Paris. Source: Labillardiere. (1800). Buka Island canoe (Solomon Islands) [digital image]. http://www.dspace.cam.ac.uk/handle/1810/239987 Modeling the relocation of immigrants from Wallacea
“The word proa comes from perahu, the word for “boat” in Malay.” Source: https://commons.wikimedia.org/wiki/File:Proa_(PSF).png
Modeling the relocation of immigrants from Wallacea
  1. A small Austronesian-speaking hamlet or village community left home for some particular local reason or reasons from somewhere in Wallacea—or possibly on the north coast of New Guinea—and made landfall in the Bismarck Archipelago.
  2. It is possible that wherever it was they came ashore, they arrived not as strangers but rather as old friends of some of the local people there in the Bismarcks (Terrell 2015).
  3. Among these immigrants were individuals skilled at pottery-making, and also skilled in the arts and rituals of building and sailing outrigger canoes with sails. Both of these technologies were new to the Bismarcks region. Moreover, such skills may not have arrived at the same time if travel back-and-forth between communities in Wallacea, northern New Guinea, and the Bismarcks became routine at least for awhile.
  4. The local people not only welcomed them, but often also acquired new ways of doing things—such as the art of pottery-making—from their immigrant neighbors, in some instances even their foreign language skills. The reverse may have also been true.
  5. Time passed, generations came and went. For now unknown reasons, it eventually became fashionable, prestigious, or perhaps even necessary for some people in the Bismarcks to set sail for islands yet farther to the south and east in the Pacific, although how many people in how many communities were involved, how often they sailed away, and for how many years this voyaging away from home in the Bismarcks went on are now all unknown and perhaps unknowable. 
  6. Even so, considering the passage of the time between (a) the first arrival of immigrants from the west and (b) the departure of some people generations later to settle down in other (more remote) places to the southeast, there is no reason to insist that these two separate episodes of human resettlement were similarly inspired or motivated (Walker and Hill 2014).
  7. Furthermore, given that both the voyaging technology and navigational skills required to colonize the more remote islands of the Pacific may have been available then only in some communities in the Bismarcks, it is not surprising that early settlers in Vanuatu, Tonga, and elsewhere had similar material culture traits (i.e., the so-called “Lapita cultural complex”).

Because the first immigrants who reached Vanuatu and Tonga were entering a vast and uninhabited part of the Pacific, it is probably not surprising that many nowadays have been seduced by the modern global distribution of Austronesian languages—from Madagascar to Rapa Nui (Easter Island) and from New Zealand to Taiwan—into thinking that such a vast geographic compass could only be the historical product of some kind of massive human migration that was singularly intentional and singularly premeditated from the very moment the first Austronesian-speaking immigrant stepped into the first canoe to sail from somewhere in island Southeast Asia  or on the north coast of New Guinea to the Bismarcks 3,000 and more years ago. It is wise to remember, therefore, that appearances can be deceiving.

Furthermore, today we know nothing about marriage (or sexual) practices in the Pacific in the prehistoric past. Although it is stating the case too simply, we do know that the basic building block of human genetic relatedness is the gene. Anyone who knows about the birds and the bees knows that genes can travel far and wide through sexual intercourse even if the people carrying them may only get as far away from home during their time on earth as the next village or two down the road. Consequently, there is no a priori reason to assume that race = language = culture. Or that genes necessarily traveled the Pacific millennia ago as the exclusive and enduring “property” of a massive and self-contained ethnic or ethnolinguistic migration that was able to keep its collective act together over thousands of miles and for hundreds, even thousands, of years. As some anthropologists like to say it, we need models of Pacific prehistory to work with that are “on the ground,” not “pie in the sky.”

Although we have been talking here almost exclusively about the Pacific Islands, the issue at stake is a global one. It is not just worrisome to find that even scientists may sometimes be unaware of the intellectual racism hidden in the conviction that the story of our species is a tale about ancestry, ancient migrations, and admixture. Commonsense ideas like these can be more than misleading. They can lend credence to other notions and old prejudices that can be harmful and sometimes deadly.  


We thank Ethan Cochrane, Mark Golitko, Tyrone Lavery, Lisa Matisoo-Smith, and Robin Torrence for assistance in the preparation of this 3-part commentary.


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© 2017 John Edward Terrell and Kevin M. Kelly. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. The statements and opinions expressed are those of the author(s) and do not constitute official statements or positions of the Editors and others associated with SCIENCE DIALOGUES.

2 thoughts on “Racial migrations and human genetics: The “game changer” in the South Pacific that wasn’t – part 3”

  1. This comment comes from Hal Levine, and has been added here at his request.

    The critique is interesting. I find the objections Terell and Kelly made about the smallness of the samples convincing and their alternative interesting; although whether the latter is going to be accepted remains to be seen. I’m not an archaeologist but their story seems less parsimonious than the hypotheses they criticise, what with friends being part of their explanation. Be that as it may, there is one thing that grates and that is their statement that lining up language, physical traits and settlement patterns is “racism” by definition . Racism is a belief in superiority accompanied by discrimination etc. Here is a definition ˈ”racism, prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one’s own race is superior. synonyms: racial discrimination, racialism, racial prejudice/bigotry…the belief that all members of each race possess characteristics, abilities, or qualities specific to that race, especially so as to distinguish it as inferior or superior to another race or races.” (Google racism).

    Although it is easy to find examples of racism that do use such elements (the authors cite one from the 1800s) Bellwood and Green along with their fellow travelers are certainly not racists. To say for example that NZ Maori are likely to be more closely related to Cook Island Maori than to Aboriginal Australians because they speak similar languages etc. is a statement about population history that is
    worthy of examination. To label people interested in such things racist is at best a simplistic way of dismissing hypotheses you don’t like.

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