Sorry about having such a long gap between posting. I've been on a couple of business trips, and when I've been home my social calendar and the hot weather haven't left many good opportunities to sit down at my computer and write.

Sea People: The Puzzle of Polynesia by Christina Thompson is a book about the history of Polynesia, the far-flung islands in the middle of the Pacific Ocean. Because there weren't written records prior to European exploration of that area, the book is also an account of how the clues were put together to arrive at the current understanding of the history there. The central question of the book is how the Polynesian people managed to reach and settle all those islands:

They had no knowledge of writing or metal tools—no maps or compasses—and yet they succeeded in colonizing the largest ocean on the planet, occupying every habitable rock between New Guinea and the Galápagos, and establishing what was, until the modern era, the largest single culture area in the world.

Polynesia is the triangle formed by Hawai'i, New Zealand, and Easter Island. In addition to those islands, it also contains Samoa, American Samoa, Tonga, Tuvalu, French Polynesia (Tahiti, etc.), Cook Islands, Wallis & Futuna, and Tokelau. Adjacent to Polynesia are other groups of Pacific islands: Micronesia (Kiribati, Marshall Islands, Federated States of Micronesia, Nauru, Palau, Guam, and the Northern Marinara Islands) and Melanesia (Fiji, Papua New Guinea, the Solomon Islands, Vanuatu, and New Caledonia). The geography of Polynesia contains a mix of 'low' and 'high' tropical islands, plus New Zealand:

All the islands in the mid-Pacific are either high or low, volcanic or coralline. But down in the southwest corner, near the ocean’s edge, there is a large and important group of islands with an entirely different geologic history. New Zealand is one of the anchoring points of the Polynesian Triangle and a key piece of the Polynesian puzzle, but it differs from other Polynesian islands in several ways. It lies much farther south, in latitudes comparable to the stretch of North America that extends from North Carolina to Maine. It is temperate, not tropical; it can be hot in summer, but in the winter, at least in the south, it snows. New Zealand is also vast by comparison, with plains, lakes, rivers, fjords, mountain ranges, and a land area more than eight times that of all the other islands of Polynesia combined.

The Maori people of New Zealand arrived from elsewhere in Polynesia only a few hundred years before Europeans did (and had to contend with terrifying moa birds), representing the final stage of Polynesian expansion. The author's husband is Maori, giving her a personal connection to the subject matter.

The book is divided into six parts. It begins with the initial contact between the Polynesians and the outside world and then in a sense goes forward in time to go back in time&mash;it recounts various explorations, studies, and theories in the order in which they developed, retracing how light was shed on the past (with a few false steps along the way). The following excerpt does a good job summarizing the approach Thompson took:

The problem, of course, is that we are talking about prehistory. It is hard enough to know what happened in the past when there exists a documentary record, but there is no written record of these events. Here, the evidence is all partial, ambiguous, open to widely differing interpretations, and in some cases so technical that it is difficult for a layperson to judge. When I first set out to write this book, I imagined I would be recounting the tale of the voyagers themselves, those daring men and women who crossed such stupendous tracts of sea and whose exploits constitute one of the greatest adventures in human history. But, almost immediately, it dawned on me that one could tell such a story only by pretending to know more than can actually be known. This realization quickly led me to another: that the story of the Polynesian settlement of the Pacific is not so much a story about what happened as a story about how we know. The evidence for what happened in the Pacific has taken different forms in different eras. In the sixteenth, seventeenth, and eighteenth centuries, it consisted of the eyewitness reports of European explorers, who left sketchy but fascinating accounts of Polynesian cultures before they had begun to change under the influence of the outside world. From the nineteenth century we have a different type of source material: Polynesian oral traditions, or what the islanders had to say about themselves. Then, starting in the early twentieth century, science began to deliver up whole new bodies of information based on biometrics, radiocarbon dating, and computer simulations. And, finally, in the 1970s, an experimental voyaging movement emerged, which added a completely different dimension to the story.

This review would be far too long if I tried to discuss all of the angles of evidence that Thompson considers. I found the parts about oral history, linguistics, and archaeology of pottery all interesting, but I'm going to focus on the computer simulations and experimental voyaging (both covered in Part 5) as these aspects fit into topics I have an ongoing interest in.

Before getting into that, I'll mention that Sea People spends a lot of time on Captain Cook, as he was one of the first people to personally experience how big the Pacific is. He visited a number of islands, and noticed that even thousands of miles apart the inhabitants looked similar and their languages sounded similar. A navigator from Tahiti named Tupaia joined his ship; I've read about the map he made before, but Sea People filled in a lot more detail:

Fifty of the names on these lists can be correlated with islands that we can identify today. The implication is striking: Tupaia and his fellow Tahitians appear to have had knowledge of islands stretching east–west from the Marquesas to Samoa, a distance of more than two thousand miles, and south some five hundred miles to the Australs. Tupaia did not claim to have visited all of the islands whose names he knew; he told Cook that he himself had firsthand knowledge of only twelve. But he had second- or thirdhand knowledge of several more;


It is a truly remarkable artifact: a translation of Tahitian geographical knowledge into European cartographic terms at the very first moment in history when such a thing might have been possible; a collaboration between two brilliant navigators coming from geographical traditions with essentially no overlap; a fusion of completely different sets of ideas.


European charts, such as those that Tupaia was introduced to by Cook, depicted the world in terms of conceptual systems that were entirely alien to Tahitians. Position, distance, and direction were defined in terms of a mathematical scheme of measurement based on the size and shape of the earth. The perspective was not that of a participant on the ground but of an observer high in the sky, the so-called bird’s-eye view. What such charts most emphatically do not capture is the way we actually experience geography—the perspective, for example, of someone standing on the deck of a boat.

Going into the second half of the twentieth century, one of the research questions about the history of Polynesia was whether new islands had been settled deliberately, or by canoes getting lost and drifting to them. Various theories were put to the test by computer simulations and experimental voyages. A well-known experimental voyage was that of Thor Heyerdahl and his raft "Kon-Tiki". His theory that the first settlers of Polynesia had drifted from South America isn't really credited anymore, but actually putting it to the test was an important development.

The way the Pacific Ocean circulates is quite consistent (see here for a discussion of circulation in another ocean) so computer modelling of the drift hypothesis was possible:

Out of more than 120,000 simulated voyages, begun at points all over the Pacific and conducted at all times of the year, some highly likely drift routes did emerge. These included Tonga to Fiji, Pitcairn to the Tuamotus, the Marquesas to the Tokelaus, and several others, all of which entailed travel from east to west. Almost no drifts going the other way, from west to east, emerged from the experiment. The results gave “no support” to the possibility of drifting along what was then envisioned as a likely Polynesian pathway from Samoa to the Marquesas, while the chance of drifting from Samoa to the Society Islands was less than one in seven hundred.

Because other evidence was suggesting the ancestors of the Polynesians had come from Asia rather than South America, they would have had to travel in the opposite direction from what accidental drifting could likely achieve. The next piece of the puzzle was to demonstrate whether deliberate long-distance voyaging would have been possible with the equipment and techniques available at the time.

Polynesian culture (and the closely related Micronesian culture) contained a unique tradition of navigation techniques (they've been mentioned in other books I've read but not in as much detail as here). These techniques included navigating by stars and swells, numerous ways to find land (from beyond visual distance), and mental models and mnenomics to assist with instrument-free navigation.

Stars appear to move across the night sky as the earth rotates, but they rise from a consistent spot on the horizon, night after night. For example, according to a circular slide rule star chart I have for my latitude, Orion rises in the east (the time it rises shifts through the year, however: 7 p.m. in December, 9 p.m. in November, 11 p.m. in October, and 1 a.m. in September), Sagittarius in the southeast, and Gemini in the northeast (of course different cultures have different constellations). The sequence of constellations that rise from a certain direction through the night define a star path.

Another technique for finding direction was to pay attention to the swells. My understanding is that long-period waves (i.e. swell) will come from a consistent direction since they require steady winds (like trade winds) blowing across long stretches of open ocean:

But they also used another very important—and, to Westerners, much less familiar—technique: that of reading the ocean swells. Swells are not the same as waves. Waves are a local phenomenon thrown up by winds in the immediate vicinity; swells, by contrast, are waves that originate far away and travel beyond the winds that generate them. The important swells, those created by enduring weather patterns like the trade winds or the westerlies in the South Pacific Ocean, tend to have long wavelengths and to move past the boat “with a slow, swelling undulation.” This does not necessarily mean they are easy to recognize, for in practice the actual pattern of waves and swells at any particular point will be a complicated mix of “systems that differ in height, length, shape, and speed moving across each other from different directions.”

For a navigator to pick out the swell, he would do something like an implicit Fourier transform:

Sometimes, [a navigator said], he would lie down on the outrigger platform, the more clearly to feel the pitch and roll of his canoe and thus disentangle the different forces.

Finding land from a distance used a variety of techniques, such as observing birds, clouds, and swell:

The last piece of the Oceanic navigational puzzle is the set of landfinding techniques, sometimes referred to as “expanding the target.” Birds, as one of Lewis’s instructors explained, “are the navigator’s very best friends.” If a low island can be seen at about ten miles, the range of terns and noddies—land birds that return to their islands at night—is twice that, while boobies, which fly “low and arrow-straight for the horizon” at dusk, are known to travel as many as fifty miles from land.


In addition to bird lore, there is cloud lore: the way clouds will move slowly over an island “as if stuck” and then speed up once they are past it; or the “brightness” of clouds over an island as compared with those over the sea; or the way a land cloud will lie, at first, like other clouds on the horizon but, if you watch long enough, will appear to hover or keep re-forming while other clouds dissipate or move on.


Finally, there is the technique known as “wave piloting.” This is a version of navigating by swells, but with the added complication that in the vicinity of islands, waves are both reflected and refracted by the land. This creates complicated patterns of interference, which in the Marshall Islands have historically been depicted by stick charts made from the ribs of palm fronds, with shells to indicate the positions of islands. These stick charts have often been described as maps, but they are not maps or charts in the way we might think of them. They are teaching tools and mnemonic devices, part of an instructional tool kit used by experienced navigators to communicate concepts, and not something that would ever be relied upon at sea.

I've seen stick charts at some maritime museums I've visited (that post also mentions experimental archaeology, which I'll be discussing below). I'm reminded of something I read in The Sea: A Cultural History by John Mack about the importance of mnenomics for traditional navigation. As I wrote in my review of that book:

In spite of the factual nature of his subject matter, [ibn Majid] did much of his writing in poetic verse. Mack draws parallels between the sensory engagement that is stimulated by poetry and the engagement with environment that good traditional navigation requires. Verse also serves a mnemonic function.

The following passages illustrate how Polynesian navigators approached their task from a different mindset than European navigators:

Carolinian navigators use a system known as etak, in which they visualize a “reference island”—which is usually a real island but may also be imaginary—off to one side of the path they are following, about midway between their starting point and their destination. As the journey progresses, this island “moves” under each of the stars in the star path, while the canoe in which the voyagers are traveling stays still. Of course, the navigators know that it is the canoe and not the islands that are moving, but this is the way they conceptualize the voyage.


What is not easily conveyed in accounts of traditional navigational techniques is a sense of how navigation is experienced by its practitioners: not as an array of discrete techniques but as “a unity,” “the sum of input from such disparate sources as stars, swells, and birds being processed through training and practice into a confident awareness of precisely where they were at any one time”—a description that, in itself, seems to capture some of the difficulty.


Tour thinking is sometimes understood to differ from map thinking in the same way that orality differs from literacy. And one can see how features of non-instrumental navigation overlap with other systems for managing knowledge in an oral culture: the first-person perspective, the emphasis on experience, the encoding of information in narrative form.

This description of tour thinking exemplifies one of the strengths of Thompson's writing. She remains aware of how different people have different perspectives shaped by their cultural background (e.g. literate cultures tend to have a more linear narrative structure than oral cultures) and points out the implications of this in several places.

All of these navigational techniques sound impressive in a book, but do they work? Without a time machine, no one can directly observe Polynesian voyages from around a millenia ago. This is where experimental archaeology comes in. It attempts to replicates past achievements using tools available at the time to provide a demonstration or proof-of-concept that a hypothesized way they were performed was possible—not to fully prove that they occurred in exactly that way. The Polynesian Voyaging Society (which is still active) undertook a seminal voyage from Hawai'i to Tahiti in a double-hulled canoe in the 1970s. Its legacy included not only scientific work, but a renewed appreciation for Polynesian culture:

Finney had written in some frustration in the 1970s that it had been “naïve” to think that the goals of “scientific research and cultural revival could be easily combined,” and there was always tension around the notion that the Polynesian Voyaging Society embodied two seemingly conflicting ways of looking at the world. But, in fact, almost everything about Hokule‘a had been syncretic from the start. The canoe itself was based on traditional designs that had been recorded in the seventeenth and eighteenth centuries by European observers, interpreted by the Chicago Art Institute–trained Hawaiian artist Herb Kane, and constructed with modern materials like fiberglass and plywood. The chants and ceremonies surrounding the voyages were a blend of contemporary Hawaiian cultural practices, ceremonies from other parts of Polynesia, and traditional sources recorded in the nineteenth century by men like Abraham Fornander and S. Percy Smith. But the most thrilling example of fusion was the navigational method pioneered by Nainoa and subsequently taught to navigators all across the Pacific: a mix of Mau’s Carolinian knowledge, modern astronomical information, and innovations that the young Hawaiian had arrived at on his own.

More recent research, including genetics—not just of the people but of the "portmanteau biota" they carried between islands (such as dogs, pigs, chickens, and rats)—is the topic of the final part of the book. To wrap this post up, I'll share the current understanding of the spread of people through the Pacific, according to Sea People:

The Lapita people were still envisioned as having reached Samoa and Tonga in the neighborhood of 900 B.C., but the initial settlement of central and eastern Polynesia had moved much closer to the present. According to the new orthodoxy, none of the archipelagoes of central and eastern Polynesia (the Society Islands, Hawai‘i, the Marquesas, Easter Island, the Cooks) is thought to have been settled before the end of the first millennium A.D., while the discovery and settlement of New Zealand was pushed as far forward as A.D. 1200.

Some of this timeline actually lines up pretty well with early research based on compiling oral history from the region:

Fornander specifically noted an efflorescence of tales about “bold expeditions, stirring adventures, and voyages undertaken to far-off lands,” from which he deduced an era of “national unrest” and “tribal commotion” right around the year 1000. Smith similarly proposed a muddled early settlement phase for New Zealand, but his dates for the arrival of the first named Maori ancestors were 1150 and 1350, exactly straddling the date proposed for the settlement of New Zealand in the cleaned-up radiocarbon chronology.

Christina Thompson really emphasizes the variety of different kinds of evidence that has gone into unravelling the history of this part of the world:

To the extent that this history has been disentangled, however, it has been thanks to input of radically different kinds. At one end of the spectrum are the mathematical models: the computer simulations, chemical analyses, statistical inferences—science with all its promise of objectivity and its periodic lapses into error. At the other, the stories and songs passed from memory to memory: the layered, subtle, difficult oral traditions, endlessly open to interpretation but unique in their capacity to speak to us, more or less directly, out of a pre-contact Polynesian past.

Overall, this was a very interesting read.

Here are a few other things I've been up to recently:

  • I went to see a production of "Measure for Measure", which is a good, thought-provoking Shakespeare play I wasn't really familiar with.
  • I made some cold brew coffee that turned out pretty well. The cold water and long time extracts different compounds than brewing with hot water. I find it has a bit of natural sweetness and hardly any bitterness.
  • I'm trying to propagate one of my cacti from some pads I pruned off.
  • In light of a book I read earlier this year, this comic amused me.