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The 15 archipelagos of East Polynesia, including New Zealand, Hawaii, and Rapa Nui, were the last habitable places on earth colonized by prehistoric humans. The timing and pattern of this colonization event has been poorly resolved, with chronologies varying by >1000 y, precluding understanding of cultural change and ecological impacts on these pristine ecosystems. In a meta-analysis of 1,434 radiocarbon dates from the region, reliable short-lived samples reveal that the colonization of East Polynesia occurred in two distinct phases: earliest in the Society Islands A.D. ~1025-1120, four centuries later than previously assumed; then after 70-265 y, dispersal continued in one major pulse to all remaining islands A.D. ~1190-1290. We show that previously supported longer chronologies have relied upon radiocarbon-dated materials with large sources of error, making them unsuitable for precise dating of recent events. Our empirically based and dramatically shortened chronology for the colonization of East Polynesia resolves longstanding paradoxes and offers a robust explanation for the remarkable uniformity of East Polynesian culture, human biology, and language. Models of human colonization, ecological change and historical linguistics for the region now require substantial revision.

Remote Oceania was colonized initially in three migratory phases: the western archipelagos of Micronesia plus eastern Melanesia out to west Polynesia in the period 3500-2800 cal BP (all dates hereafter are cal BP), central and eastern Micronesia 2200-2000 BP and east and south Polynesia 1100-700 BP. The early and late migration phases are best-known archaeologically. During these phases a number of plants and animals were introduced. Of the latter, the pig (Sus scrofa), dog (Canis familiaris), fowl or chicken (Gallus gallus) and rats (Rattus spp., especially R. exulans) were most deliberately associated with human settlement. The pattern of introductions appears to be only partly in agreement with an implication of widespread early distribution derived from the orthodox colonisation model of 'transported landscape' coupled with sophisticated seafaring. Within the two main migrations the pattern of introductions is similar. Excepting in the movement to West Micronesia, all four taxa were transported into the islands nearest their proximate sources at, or soon after, the beginning of migration, but their introduction to more remote islands was partial and patchy. Evaluation of invasibility, invasiveness and transportability characteristics amongst the four taxa suggest that island size and complexity, propagule pressure and seafaring capability were important factors in differential distribution and survival. Seafaring capability was especially important because it determined the extent of accessibility to islands near and far and the degree of propagule or introduction pressure that was exerted. Framing the archaeological data within a model of invasion biology offers a richer and more systematic approach to the complexities of introduction than adopting a culture-historical perspective.

Waka unua, Māori ‘double-hulled canoes’ with rudimentary Oceanic spritsails, have long been considered the most devolved of sailing vessels in East Polynesia, compared to an assumed sophistication of voyaging canoes in the prehistoric colonising era. This traditionalist or conventional hypothesis is discussed with reference to early historical data from New Zealand, including both written descriptions and drawings, according to the conviction that neither is intrinsically more reliable or informative than the other. Analysis of these sources, particularly those that refer to the Moutohorā (Bay of Plenty) canoe observed in 1769, does not support the conventional model. Instead of expedient construction, waka unua hulls were built to a New Zealand-wide pattern. Similarly, instead of an Oceanic spritsail, the Māori sail was an Oceanic double spritsail which had independent spars rather than a fixed mast. It was deployed before the wind and struck in reaching conditions. There is no plausible historical evidence of the Oceanic spritsail or lateen in New Zealand before the 1820s and it is argued that the Oceanic double spritsail was the only sailing rig used in pre-European New Zealand. Some inferences for understanding early East Polynesian voyaging are noted.

The pristine island ecosystems of East Polynesia were among the last places on Earth settled by prehistoric people, and their colonization triggered a devastating transformation. Overhunting contributed to widespread faunal extinctions and the decline of marine megafauna, fires destroyed lowland forests, and the introduction of the omnivorous Pacific rat (Rattus exulans) led to a new wave of predation on the biota. East Polynesian islands preserve exceptionally detailed records of the initial prehistoric impacts on highly vulnerable ecosystems, but nearly all such studies are clouded by persistent controversies over the timing of initial human colonization, which has resulted in proposed settlement chronologies varying from ≈200 B.C. to 1000 A.D. or younger. Such differences underpin radically divergent interpretations of human dispersal from West Polynesia and of ecological and social transformation in East Polynesia and ultimately obfuscate the timing and patterns of this process. Using New Zealand as an example, we provide a reliable approach for accurately dating initial human colonization on Pacific islands by radiocarbon dating the arrival of the Pacific rat. Radiocarbon dates on distinctive rat-gnawed seeds and rat bones show that the Pacific rat was introduced to both main islands of New Zealand ≈1280 A.D., a millennium later than previously assumed. This matches with the earliest-dated archaeological sites, human-induced faunal extinctions, and deforestation, implying there was no long period of invisibility in either the archaeological or palaeoecological records.

The hypothesis of Rapa Nui (Easter Island) colonisation by Amerindian voyagers has been largely dismissed archaeologically since the mid-twentiethcentury controversy generated by Thor Heyerdahl’s American Indians in the Pacific. The orthodox hypothesis today is that Rapa Nui was settled exclusively by Polynesians who, however, brought the sweet potato and a few other items from South America by return voyaging. This view is challenged by recent evidence that widespread admixture of Amerindian and East Polynesian DNA in East Polynesia, dated to the twelfth to fourteenth century AD, could represent Amerindian landfalls. Reconsideration, here, of putative Amerindian archaeological remains on Rapa Nui—notably the facade of the ceremonial platform known as Ahu Tahiri, circular stone structures known as tupa, and birdman motifs—in the light of recent, largely contextual, research also appears to offer more support for the hypothesis than hitherto. However, the argument is heavily constrained by the long absence of systematic analytical research designed to test such indications, perhaps because marginalising the Amerindian hypothesis suits archaeological perspectives on both sides of the southeast Pacific. The purpose of this review is to encourage new research on the archaeological material in question.

Debate about initial human migration across the immense area of East Polynesia has focused upon seafaring technology, both of navigation and canoe capabilities, while temporal variation in sailing conditions, notably through climate change, has received less attention. One model of Polynesian voyaging observes that as tradewind easterlies are currently dominant in the central Pacific, prehistoric colonization canoes voyaging eastward to and through central East Polynesia (CEP: Society, Tuamotu, Marquesas, Gambier, Southern Cook, and Austral Islands) and to Easter Island probably had a windward capacity. Similar arguments have been applied to voyaging from CEP to New Zealand against prevailing westerlies. An alternative view is that migration required reliable off-wind sailing routes. We investigate the marine climate and potential voyaging routes during the Medieval Climate Anomaly (MCA), A.D. 800–1300, when the initial colonization of CEP and New Zealand occurred. Paleoclimate data assimilation is used to reconstruct Pacific sea level pressure and wind field patterns at bidecadal resolution during the MCA. We argue here that changing wind field patterns associated with the MCA provided conditions in which voyaging to and from the most isolated East Polynesian islands, New Zealand, and Easter Island was readily possible by off-wind sailing. The intensification and poleward expansion of the Pacific subtropical anticyclone culminating in A.D. 1140–1260 opened an anomalous climate window for off-wind sailing routes to New Zealand from the Southern Austral Islands, the Southern Cook Islands, and Tonga/Fiji Islands. Significance South Pacific migration routes used in East Polynesian colonization (A.D. 800−1500) have been assumed to be commonly upwind, when based on an understanding of modern climate patterns. Instead, our novel paleowind field reconstructions at bidecadal resolution show that migration routes lay downwind from East Polynesia during known times of initial colonization of New Zealand and Easter Island. This finding is significant in showing that a windward seafaring capacity in Polynesian colonization voyaging was not essential, and that long-term temporal variation in sailing conditions due to the expansion of the tropics was important in shaping colonization histories. The paleoclimate reconstruction broadens colonization possibilities, and the method represents a new, globally applicable approach to understanding patterning in prehistoric maritime migration.

Prehistoric colonization of East Polynesia represents the last and most extensive of human migrations into regions previously uninhabited. Although much of East Polynesia is tropical, the southern third, dominated by New Zealand—by far the largest Polynesian landmass—ranges from a warm- to cool-temperate climate with some islands extending into the Subantarctic. The substantial latitudinal variation implies questions about biocultural adaptations of tropical people to conditions in which most of their familiar resources were absent and their agriculture marginal. Perhaps the most basic question, but one which has never been explored, is the extent to which sailing out of the tropics on long-distance colonizing voyages imposed physiological stress on canoe crews and passengers. In this paper we use trajectories of simulated voyages from Tahiti to New Zealand and Tahiti to Hawaii to obtain along-trip environmental parameters which are then used to model the energy expenditure of these long overseas journeys. Results show that travelers to New Zealand are exposed to much harsher environmental conditions, leading to significantly greater in-trip thermoregulatory demands. For both destinations, travelers with larger body sizes exhibit lower modeled heat loss and hence obtain an energetic advantage, with greater gains for females. Such physiological features, notably of Samoans who probably formed the founding population in East Polynesia, may help explain successful voyaging to temperate latitudes.

Polynesians introduced the tropical crop taro (Colocasia esculenta) to temperate New Zealand after 1280 CE, but evidence for its cultivation is limited. This contrasts with the abundant evidence for big game hunting, raising longstanding questions of the initial economic and ecological importance of crop production. Here we compare fossil data from wetland sedimentary deposits indicative of taro and leaf vegetable (including Sonchus and Rorippa spp.) cultivation from Ahuahu, a northern New Zealand offshore island, with Raivavae and Rapa, both subtropical islands in French Polynesia. Preservation of taro pollen on all islands between 1300 CE and 1550 CE indicates perennial cultivation over multiple growing seasons, as plants rarely flower when frequently harvested. The pollen cooccurs with previously undetected fossil remains of extinct trees, as well as many weeds and commensal invertebrates common to tropical Polynesian gardens. Sedimentary charcoal and charred plant remains show that fire use rapidly reduced forest cover, particularly on Ahuahu. Fires were less frequent by 1500 CE on all islands as forest cover diminished, and short-lived plants increased, indicating higher-intensity production. The northern offshore islands of New Zealand were likely preferred sites for early gardens where taro production was briefly attempted, before being supplanted by sweet potato (Ipomoea batatas), a more temperate climate-adapted crop, which was later established in large-scale cultivation systems on the mainland after 1500 CE.

Whether kumara 'sweet potato' (Ipomoea batatas) arrived in South Polynesia with initial colonisation or later is discussed in the light of recent evidence from East Polynesia and by examination and statistical modelling of radiocarbon ages associated with kumara arrival and dispersal in New Zealand. Largely unresolved difficulties in radiocarbon dating of horticultural sites preclude reaching a secure conclusion about the relative timing of kumara introduction, but strong evidence emerges of delayed dispersal southward and inland of kumara cultivation. In the short New Zealand chronology this may have been more significant than the date of arrival for the role of kumara cultivation in economic and political change.

The estimated period in which human colonization of Madagascar began has expanded recently to 5000-1000 y B.P., six times its range in 1990, prompting revised thinking about early migration sources, routes, maritime capability and environmental changes. Cited evidence of colonization age includes anthropogenic palaeoecological data 2500-2000 y B.P., megafaunal butchery marks 4200-1900 y B.P. and OSL dating to 4400 y B.P. of the Lakaton'i Anja occupation site. Using large samples of newly-excavated bone from sites in which megafaunal butchery was earlier dated >2000 y B.P. we find no butchery marks until ~1200 y B.P., with associated sedimentary and palynological data of initial human impact about the same time. Close analysis of the Lakaton'i Anja chronology suggests the site dates <1500 y B.P. Diverse evidence from bone damage, palaeoecology, genomic and linguistic history, archaeology, introduced biota and seafaring capability indicate initial human colonization of Madagascar 1350-1100 y B.P.