Identification of breadfruit (Artocarpus altilis) and South American crops introduced during early settlement of Rapa Nui (Easter Island), as revealed through starch analysis

Starch residue analysis was carried out on stone tools recovered from the bottom layer of the Anakena site on Rapa Nui (Easter Island). These deposits have been dated to AD 1000-1300 AD and so far, represent the earliest evidence of human settlement on this island. Twenty obsidian tools were analyzed. Analysis of 46 starch grains recovered from 20 obsidian tools from the earliest dated level of the Anakena site on Rapa Nui provides direct evidence for translocation of traditional crop plants at initial stages of the colonization of this island. The analysis of starch grains was based mainly on statistical methods for species identification but was complemented by visual inspection in some cases. Our results identify taxons previously unknown to have been cultivated on the island, such as breadfruit (Artocarpus altilis), Zingiber officinale (ginger), and starch grains of the Spondias dulcis and Inocarpus fagifer tropical trees. Additionally, starch grains of Colocasia esculenta (taro) and Dioscorea sp. (yam), both common species in Pacific agriculture, were identified. Furthermore, the presence of four American taxa Ipomoea batatas (sweet potato), Canna sp. (achira), Manihot esculenta (manioc), and Xanthosoma sp., was detected. The occurrence of Canna sp., M. esculenta, and Xanthosoma sp. starch grains suggests the translocation of previously not described South American cultivars into the Pacific. The detection of I. batatas from this site in Rapa Nui constitutes the earliest record of this cultigen in the Pacific. Our study provides direct evidence for translocation of a set of traditional Polynesian and South American crop plants at the initial stages of colonization in Rapa Nui.

"Feeling at home in Vanuatu": Integration of newcomers from the East during the last millennium

Several localities across the Vanuatu archipelago (Melanesia), so-called 'Polynesian Outliers', are inhabited by communities that display Polynesian linguistic and cultural features although being located outside the Polynesian Triangle. Several introductions of Polynesian genetic components to Central and Southern Vanuatu during the last millenium have resulted in the cultural distinctiveness observed among the Polynesian Outliers in Vanuatu. However, social, political or economic process surrounding the exchange of genes between Polynesian and local individuals remain unidentified. Recent bioanthropological studies suggest the existence of female mobilities from neighboring regions to Vanuatu but also to the Polynesian Outliers of Taumako (Solomon Islands) within patrilocal societies. We aim to examine the hypothesis that Polynesian biological affinities observed in ancient individuals from Vanuatu are gendered or sex-specific, and that some of the Polynesian migrations during the last millennium may have involved practices of exogamy. By reconstructing phenotypes and biological identities from 13 archaeologically-recovered human skulls (400-300 years ago) from "Polynesian-related" regions of Vanuatu, we provide new insights to better contextualize the settlement patterns of Polynesian individuals. Eastern-Pacific associated phenotype are observable in 4 women from the Eretok burial complex (Efate region) and the Polynesian Outlier of Futuna, who were buried in close proximity to individuals with Western-Pacific associated phenotype. We suggest that close integration of individuals from the East into the local Vanuatu society, as well as the practice of exogamy, might have been key processes contributing to the preservation of Polynesian cultural features in Vanuatu over the past millennium. Our finding are cross-referenced with oral records from these two areas, as well as the known genetic makeup of the Vanuatu Polynesian Outliers.

Origins of Polynesian Pigs Revealed by Mitochondrial Whole Genome Ancient DNA

Simple Summary

Retracing the ancient human migration routes in the remote islands of the Pacific relies on robust models of the origins and spread of animals that were commensal to long-distance ocean voyages. Domestic pigs (Sus scrofa) in Polynesia belong to a rare mitochondrial DNA group whose geographic origins are disputed. We report new complete genome ancient DNA that suggests all founding populations of pigs in Polynesia, first settled by people about 2800–700 years ago, can be traced back to northern peninsular Southeast Asia.

Abstract

Domestic pigs (Sus scrofa) were first transported to Polynesia through a series of long-distance voyages ultimately linked to the Neolithic expansion of Austronesian-speaking people out of Asia. The descendants of the founding pigs belong to a rare mtDNA group referred to as the “Pacific Clade” that may have originated in peninsular or island Southeast Asia. We report the first whole genome mtDNA from domestic pigs from any of the remote islands of the Pacific. In this brief report, we describe the close link we discovered between ancient mtDNA from archaeological specimens from across Polynesia and from that of modern pigs in northern peninsular Southeast Asia, specifically southern China’s Yunnan Province. More complete mtDNA coverage in commensal animals is necessary to improve our picture of the settlement of Polynesia (ca. 2800–700 years before the present) and specify the route, or routes, that pigs took from northern peninsular Southeast Asia.

Genetic characterization of populations in the Marquesas Archipelago in the context of the Austronesian expansion

Our exploration of the genetic constitution of Nuku Hiva (n = 51), Hiva Oa (n = 28) and Tahuata (n = 8) of the Marquesas Archipelago based on the analyses of genome-wide autosomal markers as well as high-resolution genotyping of paternal and maternal lineages provides us with information on the origins and settlement of these islands at the fringe of the Austronesian expansion. One widespread theme that emerges from this study is the genetic uniformity and relative isolation exhibited by the Marquesas and Society populations. This genetic homogeneity within East Polynesia groups is reflected in their limited average heterozygosity, uniformity of constituents in the Structure analyses, reiteration of complete mtDNA sequences, marked separation from Asian and other Oceanic populations in the PC analyses, limited differentiation in the PCAs and large number of IBD segments in common. Both the f3 and the Outgroup f3 results provide indications of intra-East Polynesian gene flow that may have promoted the observed intra-East Polynesia genetic homogeneity while ALDER analyses indicate that East Polynesia experienced two gene flow episodes, one relatively recent from Europe that coincides roughly with the European incursion into the region and an early one that may represent the original settlement of the islands by Austronesians. Median Network analysis based on high-resolution Y-STR loci under C2a-M208 generates a star-like topology with East Polynesian groups (especially from the Society Archipelago) in central stem positions and individuals from the different populations radiating out one mutational step away while several Samoan and outlier individuals occupy peripheral positions. This arrangement of populations is congruent with dispersals of C2a-M208 Y chromosomes from East Polynesia as a migration hub signaling dispersals in various directions. The equivalent ages of the C2a-M208 lineage of the populations in the Network corroborate an east to west flow of the most abundant Polynesian Y chromosome.

The Marquesans at the fringes of the Austronesian expansion

In the present study, 87 unrelated individuals from the Marquesas Archipelago in French Polynesia were typed using mtDNA, Y-chromosome and autosomal (STRs) markers and compared to key target populations from Island South East Asia (ISEA), Taiwan, and West and East Polynesia to investigate their genetic relationships. The Marquesas, located at the eastern-most fringes of the Austronesian expansion, offer a unique opportunity to examine the effects of a protracted population expansion wave on population structure. We explore the contribution of Melanesian, Asian and European heritage to the Marquesan islands of Nuku-Hiva, Hiva-Oa and Tahuata. Overall, the Marquesas Islands are genetically homogeneous. In the Marquesan Archipelago all of the mtDNA haplogroups are of Austronesian origin belonging to the B4a1 subhaplogroup as the region marks the end of a west to east decreasing cline of Melanesian mtDNA starting with the West Polynesian population of Tonga. Genetic discrepancies are less pronounced between the Marquesan and Society islands, and among the Marquesan islands. Interestingly, a number of Melanesian, Polynesian and European Y-chromosome haplogroups exhibit very different distribution between the Marquesan islands of Nuku Hiva and Hiva Oa, likely resulting from drift, differential migration involving various source populations and/or unique trading routes.