East Polynesia was the geographic terminus of prehistoric human expansion across the globe and the southern Cook Islands, the first archipelago west of Samoa, a gateway to this region. Fourteen new radiocarbon dates from one of the oldest human settlements in this archipelago, the Ureia site (AIT-10) on Aitutaki Island, now indicate occupation from cal AD 1225–1430 (1σ), nearly 300 yr later than previously suggested. Although now among the most securely dated central East Polynesian sites, the new age estimate for Ureia places it outside the settlement period of either the long or short chronology models. The new dates have, however, led to a comfortable fit with the Ureia biological evidence, which suggests not a virgin landscape, but a highly a modified fauna and flora. The results also provide the first systematic demonstration of inbuilt age in tropical Pacific trees, a finding that may explain widely divergent 14C results from several early East Polynesian sites and has implications for the dating of both island colonization and subsequent intra-island dispersals.
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.
Measurements of the microscopic properties of dense matter have been demonstrated by applying spectrally resolved multi-keV x-ray scattering. The scattering spectra from solid density beryllium show the inelastic Compton-down shifted feature that is spectrally broadened when heating the solid density plasmas isochorically and homogeneously to temperatures of several times the Fermi energy. The spectral shape of the inelastic scattering component provides an accurate measurement of the temperature, and the intensity ratio of inelastic to elastic scattering measures the ionization balance. These measurements extend the powerful technique of Thomson scattering [S. H. Glenzer et al., Phys. Plasmas 7, 2149 (1999)] to the x-ray regime for independent measurements of the plasma parameters of solid density and super dense laboratory plasmas. This new technique has wide applications to investigate the previously inaccessible regimes of dense matter, from Fermi degenerate, to strongly coupled, to high temperature ideal gas plasmas.
Radiocarbon determinations were obtained for archaeological sites at Cemetery Bay and Emily Bay, Norfolk Island. Sample materials were rat bone gelatin, marine shell and wood charcoal. Ages on bone gelatin are contradictory and suggest a laboratory problem, while ages on marine shell appear to include an old-carbon offset of 500-600 years: dates on these samples are consistent with those on charcoal when appropriate corrections are made. Ages on charcoal were divided according to the expected inbuilt age of the sample taxa. The samples with lowest inbuilt age were subjected to Bayesian analysis which concluded that the main archaeological site, at Emily Bay, had been occupied from the early thirteenth to the early fifteenth centuries A.D. The Norfolk Island settlement occurs within the same age range as other Polynesian settlements of southern islands.
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