Evidence for early life in Earth’s oldest hydrothermal vent precipitates

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago

The archaeological documentation and geochemistry of the Rua Tokitoki adze quarry and the Poike fine-grain basalt source on Rapa Nui (Easter Island)

Rapa Nui is famous for its moai (statues) and ahu (platforms), yet research into the island's many basalt quarries, sources and workshops is limited. These geological and archaeological sites provided the raw materials for tools such as toki (adzes and picks), which facilitated the manufacture of Easter Island's iconic stonework. Other basaltic tools such as hoe (knives), ohio (axes) and mangai ma'ea (stone fishhooks) served for subsistence practices. However, little is known about the sources of these artefacts, the sequence of their manufacture and their geochemical compositions. In this paper, we provide archaeological site descriptions and geochemistry of source material from the Rua Tokitoki quarry and a fine-grain basalt locality on Poike to contribute towards an understanding of prehistoric mining, social interaction and elite oversight on this isolated East Polynesian outpost

Determining the geochemical variability of fine-grained basalt sources/quarries for facilitating prehistoric interaction studies in Polynesia

Polynesian adze sourcing studies that rely on geochemical analyses to assign distant artefacts to a source or quarry have been undertaken for more than three decades. Understanding intra-source geochemical variability is essential for robust artefact source assignments, yet these data are not available for most quarries. We provide a seven-step protocol for sampling source rocks and associated artefacts at quarries and, using the large Eiao quarry (Marquesas Islands) as a case study, demonstrate the efficacy of the protocol. A "sampling to redundancy" statistical procedure documents that ∼7-11 samples are required to capture the variability of 10 oxides, 49 trace elements and seven isotope ratios. We advocate using the broadest array of fully quantitative geochemical values to characterise quarries and sources that will facilitate current and future sourcing studies. In the biological sense, this is analogous to the formal description of a holotype. Quarry samples should also be collected and curated to enable research when new protocols are established and more precise and accurate geochemical techniques develop

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 finegrained 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