Pofatu, a curated and open-access database for geochemical sourcing of archaeological materials.

Compositional analyses have long been used to determine the geological sources of artefacts. Geochemical "fingerprinting" of artefacts and sources is the most effective way to reconstruct strategies of raw material and artefact procurement, exchange or interaction systems, and mobility patterns during prehistory. The efficacy and popularity of geochemical sourcing has led to many projects using various analytical techniques to produce independent datasets. In order to facilitate access to this growing body of data and to promote comparability and reproducibility in provenance studies, we designed Pofatu, the first online and open-access database to present geochemical compositions and contextual information for archaeological sources and artefacts in a form that can be readily accessed by the scientific community. This relational database currently contains 7759 individual samples from archaeological sites and geological sources across the Pacific Islands. Each sample is comprehensively documented and includes elemental and isotopic compositions, detailed archaeological provenance, and supporting analytical metadata, such as sampling processes, analytical procedures, and quality control.

Cook Island artifact geochemistry demonstrates spatial and temporal extent of pre-European interarchipelago voyaging in East Polynesia.

The Cook Islands are considered the "gateway" for human colonization of East Polynesia, the final chapter of Oceanic settlement and the last major region occupied on Earth. Indeed, East Polynesia witnessed the culmination of the greatest maritime migration in human history. Perennial debates have critiqued whether Oceanic settlement was purposeful or accidental, the timing and pathways of colonization, and the nature and extent of postcolonization voyaging-essential for small founding groups securing a lifeline between parent and daughter communities. Centering on the well-dated Tangatatau rockshelter, Mangaia, Southern Cook Islands, we charted the temporal duration and geographic spread of exotic stone adze materials-essential woodworking tools found throughout Polynesia- imported for more than 300 y beginning in the early AD 1300s. Using a technique requiring only 200 mg of sample for the geochemical analysis of trace elements and isotopes of fine-grained basalt adzes, we assigned all artifacts to an island or archipelago of origin. Adze material was identified from the chiefly complex on the Austral Islands, from the major adze quarry complex on Tutuila (Samoa), and from the Marquesas Islands more than 2,400 km distant. This interaction is the only dated example of down-the-line exchange in central East Polynesia where intermediate groups transferred commodities attesting to the interconnectedness and complexity of social relations fostered during postsettlement voyaging. For the Cook Islands, this exchange may have lasted into the 1600s, at least a century later than other East Polynesian archipelagos, suggesting that interarchipelago interaction contributed to the later development of social hierarchies.

Myth or relict: Does ancient DNA detect the enigmatic Upland seal?

The biological status of the so-called 'Upland seal' has remained contentious ever since historical records described a distinct seal from the uplands of New Zealand's (NZ) remote sub-Antarctic islands. Subsequent genetic surveys of the NZ fur seal (Arctocephalus forsteri) detected two highly-divergent mtDNA clades, hypothesized to represent a post-sealing hybrid swarm between 'mainland' (Australia-NZ; A. forsteri) and sub-Antarctic (putative 'Upland'; A. snaresensis) lineages. We present ancient-DNA analyses of prehistoric mainland NZ and sub-Antarctic fur seals, revealing that both of these genetic lineages were already widely distributed across the region at the time of human arrival. These findings indicate that anthropogenic factors did not contribute to the admixture of these lineages, and cast doubt on the validity of the Upland seal. Human-mediated impacts on Arctocephalus genetic diversity are instead highlighted by a dramatic temporal haplotype frequency-shift due to genetic drift in heavily bottlenecked populations following the cessation of industrial-scale harvesting. These extinction-recolonisation dynamics add to a growing picture of human-mediated change in NZ's coastal and marine ecosystems.

Bayesian modeling and chronological precision for Polynesian settlement of Tonga.

First settlement of Polynesia, and population expansion throughout the ancestral Polynesian homeland are foundation events for global history. A precise chronology is paramount to informed archaeological interpretation of these events and their consequences. Recently applied chronometric hygiene protocols excluding radiocarbon dates on wood charcoal without species identification all but eliminates this chronology as it has been built for the Kingdom of Tonga, the initial islands to be settled in Polynesia. In this paper we re-examine and redevelop this chronology through application of Bayesian models to the questioned suite of radiocarbon dates, but also incorporating short-lived wood charcoal dates from archived samples and high precision U/Th dates on coral artifacts. These models provide generation level precision allowing us to track population migration from first Lapita occupation on the island of Tongatapu through Tonga's central and northern island groups. They further illustrate an exceptionally short duration for the initial colonizing Lapita phase and a somewhat abrupt transition to ancestral Polynesian society as it is currently defined.

High precision u/th dating of first Polynesian settlement.

Previous studies document Nukuleka in the Kingdom of Tonga as a founder colony for first settlement of Polynesia by Lapita peoples. A limited number of radiocarbon dates are one line of evidence supporting this claim, but they cannot precisely establish when this event occurred, nor can they afford a detailed chronology for sequent occupation. High precision U/Th dates of Acropora coral files (abraders) from Nukuleka give unprecedented resolution, identifying the founder event by 2838±8 BP and documenting site development over the ensuing 250 years. The potential for dating error due to post depositional diagenetic alteration of ancient corals at Nukuleka also is addressed through sample preparation protocols and paired dates on spatially separated samples for individual specimens. Acropora coral files are widely distributed in Lapita sites across Oceania. U/Th dating of these artifacts provides unparalleled opportunities for greater precision and insight into the speed and timing of this final chapter in human settlement of the globe.

Stone adze compositions and the extent of ancient Polynesian voyaging and trade.

The last region on Earth settled by humans during prehistory was East Polynesia. Hawaiian oral histories mention voyaging from Hawai'i to Tahiti and back via the Tuamotus, an open ocean journey of several thousands of kilometers. The trace element and isotope chemistries of a stone adze recovered from the Tuamotu Archipelago are unlike those of sources in central Polynesia but are similar to the Kaho'olawe Island hawaiite, in the Hawaiian Islands, supporting the oral histories. Other adzes collected from the low coral islands of the northwest Tuamotus have sources in the Marquesas, Austral and Society Islands, and the Pitcairn Group, confirming that trade was widespread within East Polynesia.