Offsetting these fearsome disadvantages, Henderson does have attractions. In the reef and shallow waters nearby live lobsters, crabs, octopus, and a limited variety of fish and shellfish—unfortunately, not including black-lipped pearl oyster. On Henderson is Southeast Polynesia’s sole known turtle nesting beach, where green turtles come ashore to lay eggs between January and March of each year. Henderson formerly supported at least 17 species of breeding seabirds, including petrel colonies possibly as large as millions of birds, whose adults and chicks would have been easy to catch on the nest—enough for a population of a hundred people each to eat one bird every day of the year without endangering the colonies’ survival. The island was also home to nine species of resident land birds, five of them flightless or weak fliers and hence easy to catch, including three species of large pigeons that would have been especially delectable.
All those features would have made Henderson a great place for an afternoon picnic ashore, or for a short vacation to glut yourself on seafood and birds and turtles—but a risky and marginal home in which to try to eke out a permanent existence. Weisler’s excavations nevertheless showed, to the surprise of anyone who has seen or heard of Henderson, that the island did evidently support a permanent tiny population, possibly comprising a few dozen people who went to extreme effort in order to survive. Proof of their former presence is provided by 98 human bones and teeth representing at least 10 adults (both men and women, some of them over 40 years old), six teenaged boys and girls, and four children in the age range of 5 to 10 years. The children’s bones in particular suggest a resident population; modern Pitcairn Islanders usually don’t take young children when they visit Henderson to collect wood or seafood.
Further evidence of human use is a huge buried midden, one of the largest known from Southeast Polynesia, running for 300 yards in length and 30 yards in width along the north-coast beach facing the only passage through Henderson’s fringing reef. Among the midden’s garbage left behind from generations of people feasting, and identified in small test pits excavated by Weisler and his colleagues, are enormous quantities of fish bones (14,751 fish bones in just two-thirds of a cubic yard of sand tested!), plus 42,213 bird bones comprising tens of thousands of bones of seabirds (especially petrels, terns, and tropicbirds) and thousands of bones of land birds (especially the flightless pigeons, rail, and sandpiper). When one extrapolates from the number of bones in Weisler’s small test pits to the likely number in the whole midden, one calculates that Henderson Islanders must have disposed of the remains of tens of millions of fish and birds over the centuries. The oldest human-associated radiocarbon date on Henderson is from that midden, and the next-oldest date is from the turtle nesting beach on the northeast coast, implying that people settled first in those areas where they could glut themselves on wild-caught food.
Where could people live on an island that is nothing more than an uplifted coral reef covered with low trees? Henderson is unique among islands inhabited or formerly inhabited by Polynesians in its almost-complete lack of evidence for buildings, such as the usual houses and temples. There are only three signs of any construction: a stone pavement and post holes in the midden, suggesting the foundations of a house or shelter; one small low wall for protection against the wind; and a few slabs of beach rock for a burial vault. Instead, literally every cave and rock shelter near the coast and with a flat floor and accessible opening—even small recesses only three yards wide and two yards deep, barely large enough for a few people to seek protection from the sun—contained debris testifying to former human habitation. Weisler found 18 such shelters, of which 15 were on the heavily used north, northeast, and northwest coasts near the only beaches, and the other three (all of them very cramped) were on the eastern or southern cliffs. Because Henderson is small enough that Weisler was able to survey essentially the entire coast, the 18 caves and rock shelters, plus one shelter on the north beach, probably constitute all the “dwellings” of Henderson’s population.
Charcoal, piles of stones, and relict stands of crop plants showed that the northeast part of the island had been burned and laboriously converted to garden patches where crops could be planted in natural pockets of soil, extended by piling surface stones into mounds. Among the Polynesian crops and useful plants that were introduced intentionally by the settlers, and that have been identified in Henderson archaeological sites or that still grow wild on Henderson today, are coconuts, bananas, swamp taro, possibly taro itself, several species of timber trees, candlenut trees whose nut husks are burned for illumination, hibiscus trees yielding fiber for making rope, and the ti shrub. The latter’s sugary roots serve usually just as an emergency food supply elsewhere in Polynesia but were evidently a staple vegetable food on Henderson. Ti leaves could be used to make clothing, house thatching, and food wrappings. All of those sugary and starchy crops add up to a high-carbohydrate diet, which may explain why the teeth and jaws of Henderson Islanders that Weisler found exhibit enough signs of periodontal disease, tooth wear, and tooth loss to give nightmares to a dentist. Most of the islanders’ protein would have come from the wild birds and seafood, but finds of a couple of pig bones show that they kept or brought pigs at least occasionally.
Thus, Southeast Polynesia presented colonists with only a few potentially habitable islands. Mangareva, the one capable of supporting the largest population, was largely self-sufficient in the necessities for Polynesian life, except for lacking high-quality stone. Of the other two islands, Pitcairn was so small, Henderson so ecologically marginal, that each could support only a tiny population unable to constitute a viable human society in the long run. Both were also deficient in important resources—Henderson so much so that we moderns, who wouldn’t dream of going there even for a weekend without a full tool chest, drinking water, and food other than seafood, find it mind-boggling that Polynesians managed to survive there as residents. But both Pitcairn and Henderson offered compensating attractions to Polynesians: high-quality stone on the former, abundant seafood and birds on the latter.
Weisler’s archaeological excavations uncovered extensive evidence of trade among all three islands, whereby each island’s deficiencies were filled by the other islands’ surpluses. Trade objects, even those (such as ones of stone) lacking organic carbon suitable for radiocarbon dating, can still be dated by radiocarbon measurements on charcoal excavated from the same archaeological layer. In that way, Weisler established that trade began at least by the year A.D. 1000, probably simultaneously with the first settlement by humans, and continued for many centuries. Numerous objects excavated at Weisler’s sites on Henderson could immediately be identified as imports because they were made from materials foreign to Henderson: oyster shell fishhooks and vegetable peelers, volcanic glass cutting tools, and basalt adzes and oven stones.
Where did those imports come from? A reasonable guess is that the oyster shell for fishhooks came from Mangareva, because oysters are abundant there but absent on Pitcairn as well as on Henderson, and other islands with oyster beds are much more distant than Mangareva. A few oyster shell artifacts have also been found on Pitcairn and are similarly presumed to have come from Mangareva. But it is a much more difficult problem to identify origins of the volcanic stone artifacts found on Henderson, because both Mangareva and Pitcairn, as well as many other distant Polynesian islands, have volcanic sources.
Hence Weisler developed or adapted techniques for discriminating among volcanic stones from different sources. Volcanoes spew out many different types of lava, of which basalt (the category of volcanic stone occurring on Mangareva and Pitcairn) is defined by its chemical composition and color. However, basalts from different islands, and often even from different quarries on the same island, differ from each other in finer details of chemical composition, such as their relative content of major elements (like silicon and aluminum) and minor elements (like niobium and zirconium).
An even finer discriminating detail is that the element lead occurs naturally as se
veral isotopes (i.e., several forms differing slightly in atomic weight), whose proportions also differ from one basalt source to another. To a geologist, all these details of composition constitute a fingerprint that may allow one to identify a stone tool as coming from one particular island or quarry.
Weisler analyzed the chemical composition and, with a colleague, the lead isotope ratios in dozens of stone tools and stone fragments (possibly broken off in the course of preparing or repairing stone tools) that he had excavated from dated layers of archaeological sites on Henderson. For comparison, he analyzed volcanic rocks from quarries and rock outcroppings on Mangareva and Pitcairn, the most likely sources of rock imported to Henderson. Just to be sure, he also analyzed volcanic rocks from Polynesian islands that were much more distant and hence less likely to have served as sources of Henderson imports, including Hawaii, Easter, Marquesas, Societies, and Samoa.
The conclusions emerging from these analyses were unequivocal. All analyzed pieces of volcanic glass found on Henderson originated at the Down Rope quarry on Pitcairn. That conclusion had already been suggested by visual inspection of the pieces, even before chemical analysis, because Pitcairn volcanic glass is colored so distinctively with black and gray patches. Most of Henderson’s basalt adzes, and its basalt flakes likely to have resulted from adze-making, also originated from Pitcairn, but some came from Mangareva. On Mangareva itself, although far fewer searches have been made for stone artifacts than on Henderson, some adzes were also evidently made from Pitcairn basalt, imported presumably because of its superiority to Mangareva’s own basalt. Conversely, of the vesicular basalt stones excavated on Henderson, most came from Mangareva, but a minority were from Pitcairn. Such stones were regularly used throughout Polynesia as oven stones, to be heated in a fire for cooking, much like the charcoal bricks used in modern barbecues. Many of those putative oven stones were found in cooking pits on Henderson and showed signs of having been heated, confirming their surmised function.
In short, archaeological studies have now documented a former flourishing trade in raw materials and possibly also in finished tools: in oyster shell, from Mangareva to Pitcairn and Henderson; in volcanic glass, from Pitcairn to Henderson; and in basalt, from Pitcairn to Mangareva and Henderson, and from Mangareva to Henderson. In addition, Polynesia’s pigs and its bananas, taro, and other main crops are species that did not occur on Polynesian islands before humans arrived. If Mangareva was settled before Pitcairn and Henderson, as seems likely because Mangareva is the closest of the three to other Polynesian islands, then trade from Mangareva probably also brought the indispensable crops and pigs to Pitcairn and Henderson. Especially at the time when Mangareva’s colonies on Pitcairn and Henderson were being founded, the canoes bringing imports from Mangareva represented an umbilical cord essential for populating and stocking the new colonies, in addition to their later role as a permanent lifeline.
As for what products Henderson exported to Pitcairn and Mangareva in return, we can only guess. They must have been perishable items unlikely to survive in Pitcairn and Mangareva archaeological sites, since Henderson lacks stones or shells worth exporting. One plausible candidate is live sea turtles, which today breed in Southeast Polynesia only on Henderson, and which throughout Polynesia were prized as a prestigious luxury food consumed mainly by chiefs—like truffles and caviar nowadays. A second candidate is red feathers from Henderson’s parrot, fruit dove, and red-tailed tropicbird, red feathers being another prestigious luxury item used for ornaments and feather cloaks in Polynesia, analogous to gold and sable fur today.
However, then as now, exchanges of raw materials, manufactured items, and luxuries would not have been the sole motive for transoceanic trade and travel. Even after Pitcairn’s and Henderson’s populations had grown to their maximum possible size, their numbers—about a hundred and a few dozen individuals respectively—were so low that people of marriageable age would have found few potential partners on the island, and most of those partners would have been close relatives subject to incest taboos. Hence exchanges of marriage partners would have been an additional important function of the trade with Mangareva. It would also have served to bring skilled craftspeople with technical skills from Mangareva’s large population to Pitcairn and Henderson, and to reimport crops that by chance had died out in Pitcairn’s and Henderson’s small cultivable areas. In the same way, more recently the supply fleets from Europe were essential not only for populating and stocking but also maintaining Europe’s overseas colonies in America and Australia, which required a long time to develop even rudiments of self-sufficiency.
From the perspective of Mangarevans and Pitcairn Islanders, there would have been still another likely function of the trade with Henderson. The journey from Mangareva to Henderson would take four or five days by Polynesian sailing canoes; from Pitcairn to Henderson, about one day. My own perspective on sea journeys in Pacific native canoes is based on much briefer voyages, which left me constantly terrified of the canoe’s capsizing or breaking up and in one case nearly cost me my life. That makes the thought of a several-day canoe voyage across open ocean intolerable to me, something that only a desperate need to save my life could induce me to undertake. But to modern Pacific seafaring peoples, who sail their canoes five days just to buy cigarettes, the journeys are part of normal life. For the former Polynesian inhabitants of Mangareva or Pitcairn, a visit to Henderson for a week would have been a wonderful picnic, a chance to feast on nesting turtles and their eggs and on Henderson’s millions of nesting seabirds. To Pitcairn Islanders in particular, living on an island without reefs or calm inshore waters or rich shellfish beds, Henderson would also have been attractive for fish, shellfish, and just for the chance to hang out on the beach. For the same reason, the descendants of the Bounty mutineers today, bored with their tiny island prison, jump at the chance of a “vacation” on the beach of a coral atoll a few hundred miles distant.
Mangareva, it turns out, was the geographic hub of a much larger trade network, of which the ocean journey to Pitcairn and Henderson a few hundred miles to the southeast was the shortest spoke. The longer spokes, of about a thousand miles each, connected Mangareva to the Marquesas to the north-northwest, to the Societies to the west-northwest, and possibly to the Australs due west. The dozens of low coral atolls of the Tuamotu Archipelago offered small intermediate stepping-stones for breaking up these journeys. Just as Mangareva’s population of several thousand people dwarfed that of Pitcairn and Henderson, the populations of the Societies and Marquesas (around a hundred thousand people each) dwarfed that of Mangareva.
Hard evidence for this larger trade network emerged in the course of Weisler’s chemical studies of basalt, when he had the good fortune to identify two adzes of basalt originating from a Marquesas quarry and one adze from a Societies quarry among 19 analyzed adzes collected on Mangareva. Other evidence comes from tools whose styles vary from island to island, such as adzes, axes, fishhooks, octopus lures, harpoons, and files. Similarities of styles between islands, and appearances of examples of one island’s type of tool on another island, attest to trade especially between the Marquesas and Mangareva, with an accumulation of Marquesas-style tools on Mangareva around A.D. 1100-1300 suggesting a peak in interisland voyaging then. Still further evidence comes from studies by the linguist Steven Fischer, who concludes that the Mangarevan language as known in recent times is descended from the language originally brought to Mangareva by its first settlers and then heavily modified by subsequent contact with the language of the southeastern Marquesas (the portion of the Marquesas Archipelago closest to Mangareva).
As for the functions of all that trade and contact in the larger network, one was certainly economic, just as in the smaller Mangareva/Pitcairn/ Henderson network, because the networks’ archipelagoes complemented one another in resources. The Marquesas were the “motherland,” with a big land area and human population and one good basalt quarry, but poor marine resources because there were no lagoons or f
ringing reefs. Mangareva, a “second motherland,” boasted a huge and rich lagoon, offset by a small land area and population and inferior stone. Mangareva’s daughter colonies on Pitcairn and Henderson had the drawbacks of a tiny land area and population but great stone on Pitcairn and great feasting on Henderson. Finally, the Tuamotu Archipelago offered only a small land area and no stone at all, but good seafood and a convenient stepping-stone location.
Trade within Southeast Polynesia continued from about A.D.1000 to 1450, as gauged by artifacts in radiocarbon-dated archaeological layers on Henderson. But by A.D. 1500, the trade had stopped, both in Southeast Polynesia and along the other spokes radiating from Mangareva’s hub. Those later archaeological layers on Henderson contain no more imported Mangareva oyster shell, no more Pitcairn volcanic glass, no more Pitcairn fine-grained basalt for cutting tools, and no more Mangareva or Pitcairn basalt oven stone. Apparently the canoes were no longer arriving from either Mangareva or Pitcairn. Because trees on Henderson itself are too small to make canoes, Henderson’s population of a few dozen was now trapped on one of the most remote, most daunting islands in the world. Henderson Islanders confronted a problem that seems insoluble to us: how to survive on a raised limestone reef without any metal, without stones other than limestone, and without imports of any type.
Collapse: How Societies Choose to Fail or Succeed Page 17