Racial migrations and human genetics: The “game changer” in the South Pacific that wasn’t – part 1

John Edward Terrell and Kevin M. Kelly


Here’s a hint about why scholars can be so captivated by what is basically an old-fashioned racial migration argument. They are apparently forgetting what they have been taught about the difference between a rhetorical argument and a scientific one.

The is part 1 of a 3 part commentary


THE IDEA THAT ONCE UPON A TIME the many islands of the South Pacific were colonized by different racial migrations out of Asia or the Americas (the latter a minority view) is as old as the hills. Or at any rate, at least as old as the earliest known encounters after 1492 between Europeans and the people living there.

1852 Bocage Map of Australia and Polynesia. The colored boundary lines show how this part of the world has long been subdivided into four cartographic regions labeled here as Malaisie (Malaysia), Micronesie (Micronesia), Polynesie (Polynesia), and Melanesie (Melanesia). Source: https://upload.wikimedia.org/wikipedia/commons/a/a2/1852_Bocage_Map_of_Australia_and_Polynesia_-_Geographicus_-_Oceanie-bocage-1852.jpg

The apparent remoteness and isolation of these islands and their inhabitants have long fueled the notion that here, if not necessarily elsewhere on earth, “race, language, and culture” all formerly tracked one another so closely that today, for instance, language differences can still be used successfully—and scientifically—not only to circumscribe and label separate “populations” in the Pacific (e.g., as different “ethnolinguistic groups,” ‘races,” and the like), but can also tell us how to reconstruct the prehistory and ancient migrations of separate and distinct “peoples” out into Oceania (Terrell et al. 1997).

It is generally considered impolite to say so, but the conventional word for this type of thinking is the word racism.

What seems astonishing is that racial thinking like this still frames how archaeologists, linguists, historians, social anthropologists, and human geneticists think about Pacific Islanders and write about their past. The most recent instance of this almost universal practice is possibly also the most revealing example of why otherwise informed scholars find themselves still under the spell of such an antiquated and unscientific idea.

Melanesians and Polynesians

As early as 1813 James Cowles Prichard was formally proposing—as others had earlier done more anecdotally—that the inhabitants of the Pacific Islands starting with New Guinea and neighboring places and moving on out eastward could be divided into “two principal classes.” In his own words (quoted in: Terrell et al. 2001):

The tribes which belong to the first of these are, strictly speaking, savages. They are universally in that rude unimproved state, which precedes all division of professions and employments. Consequently their political condition is that of perfect equality without any difference of ranks. Their physical character is of the rudest kind. Their form and complexion
approximate to those of the Negro.

Pritchard called these rude savages “the race of the Papuas.” Others would come to favor instead the term “Melanesians” (i.e., “black islanders”). He did not offer a name to use for the other—and supposedly superior—class of people except to say that such tribes were to be found in “the more distant regions of the Pacific Ocean.”

By 1843, his uncertainty about how to label the latter class of tribes had been resolved in favor of calling them “Malayo-Polynesians” since by then “a real kindred, or community of origin” had been established “by affinity of language” between islanders in Southeast Asia (i.e., “Malays”) and those in the more remote parts of Oceania, who were by then often labeled as Polynesians (i.e., “people of the many islands”).

Today the favorite label for the “affinity of language” noted by Pritchard and others in the 19th century between people in Polynesia and some of the inhabitants of Island Southeast Asia is the linguist’s label Austronesian.  Nowadays, too, those said to be in Pritchard’s so-called class of savages are generally called “Papuans,” although the label “Melanesians” is also still used by some.

Racial redux

Under the headline “‘Game-changing’ study suggests first Polynesians voyaged all the way from East Asia,” Ann Gibbons, a writer at Science magazine who had written previously about the origins of the Polynesians (Gibbons 1994, 2001), announced in surprisingly unqualified terms on 3 October 2016 that the identity of the first settlers of Polynesia was at last known, thanks to a paper then just published in Nature reporting on the first genome‑wide study of ancient DNA from  prehistoric Polynesians (Skoglund et al. 2016). Lo and behold, their ancestors were ancient East Asian mariners “who swept out into the Pacific. It wasn’t until much later that Melanesians, probably men, ventured out into Oceania and mixed with the Polynesians.”

To clinch the story, she then quotes experts who apparently ought to know what they are talking about.

“The paper is a game‑changer,” says Cristian Capelli, a population geneticist at the University of Oxford in the United Kingdom, noting that that it settles a decades‑long dispute. By showing that the East Asians hopscotched past islands already populated by Melanesians without picking up their genes, it is also a case study in how culture can initially bar mixing between groups. “Farmers move in and don’t mix much with the hunter‑ gatherers,” says evolutionary geneticist Mark Thomas of University College London. “We see this again and again and again” elsewhere in the world.

Not so fast

The late population geneticist and mathematical ecologist Richard Levins is famous in scientific circles for once having declared in no uncertain terms that “truth is the intersection of independent lies.’’  Given that what Gibbons, Capelli, and Thomas are saying is intellectually—if not necessarily politically—racist, why are they so confident? Particularly since the claim being endorsed is based on DNA extracted from only four skulls dating to around 3,000 or so years ago (three from Vanuatu, and one from the Tongan Islands) compared with the DNA of less than 800 present-day individuals from 83 places in Asia and Oceania.

To a cautious statistical mind, such figures ought to raise the worry that not enough is known about human genetic variation in this part of the world to warrant going far out on a limb by declaring resolutely that science has now told us not only where the ancestors of the Polynesians came from, but also how.

Add to this concern the additional information that all four of the women in the archaeological sample from the Pacific display their strongest apparent genetic ties with Taiwan—currently the most popular place to start the purported ancient migration to Polynesia—and with the Philippines.* Does a modern comparative DNA sampling of 778 individuals from 83 places in Asia and Oceania tell us enough about genetic similarities and differences throughout this immense region to overrule the reasonable doubt that linking the four prehistoric women with present-day people in Taiwan and the Philippines wasn’t exactly an unpredictable finding? Isn’t it reasonable to suspect this study might be biased, i.e., is an example of looking specifically for something—a genetic connection with Taiwan, in particular—where you most hope to find it?

Two alternative stories

The research report in Nature that Ann Gibbons wrote about in Science last October has 31 credited authors, a global mix of geneticists and archaeologists. Their report starts off with the assertion: “Pacific islanders today derive from a mixture of two highly divergent ancestral populations.” These authors then go on to tell us that there are two alternative stories—they call them hypotheses—about these two primal races (a word they do not use), and they say they now know which of the two to believe.

Both stories accept as true the unstated premise that biology, language, and culture co-vary closely with one another. The first story is an old tale still favored by some archaeologists (Bellwood 2011). If (a) race, language, and culture co-vary, and (b) Polynesians today speak languages of Southeast Asian origin (i.e., Austronesian, formerly called “Malayo-Polynesian”), then (c) it follows that the ancestors of the Polynesians came from Southeast Asia.  The second story is a more recent alternative reconstruction of Polynesian origins (Green 2003). If (a) race, language, and culture co-vary, and (b) the so-called “Lapita cultural complex” archaeologically associated with the first settlers of Polynesia is a cultural mix of Southeast Asian and Melanesian traits, then (c) the Polynesians racially must also be of similarly mixed biological origin.

Needless to say, these collaborators would not have written their report if they had found they couldn’t adjudicate the right choice between these two alternative stories. And they do not disappoint us: “Our study has shown that many of the first humans in Remote Oceania had little, if any, Papuan ancestry, in stark contrast [an odd choice of words?] to the situation today.” And if so, the second story evidently can’t be correct, right?

But this is not all they have to conclude. In their estimation: “Systematic study of ancient DNA from throughout Remote Oceania should make it possible to provide a detailed chronicle of the population movements and sex-biased population mixtures that shaped the ancestry of present-day Oceanians.”

Should we accept as true what they tell us? Is there a better way to think about what they report? In other words, what’s the chance they have been barking up the wrong stories altogether?

Part 2: Necessary, plausible, and sufficient


*  Only 14 of the 83 places in their comparative sample are located in Island Southeast Asia; 2 of these are on Taiwan and 6 in the Philippines. None of the other 69 localities is in the region between the Philippines and northern New Guinea except for a single sample of 10 individuals from Sulawesi. We return to these figures in Part 2 of this 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.

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