Language continuity despite population replacement in Remote Oceania

Scientific Reports, 2020

People in the Solomon Islands today are considered to have derived from Asian- and Papuan-related ancestors. Papuan-related ancestors colonized Near Oceania about 47,000 years ago, and Asian-related ancestors were Austronesian (AN)-speaking population, called Lapita, who migrated from Southeast Asia about 3,500 years ago. These two ancestral populations admixed in Near Oceania before the expansion of Lapita people into Remote Oceania. To understand the impact of the admixture on the adaptation of AN-speaking Melanesians in Near Oceania, we performed the genome-wide single nucleotide polymorphism (SNP) analysis of 21 individuals from Munda, the main town of the New Georgia Islands in the western Solomon Islands. Population samples from Munda were genetically similar to other Solomon Island population samples. The analysis of genetic contribution from the two different ancestries to the Munda genome revealed significantly higher proportions of Asian- and Papuan-related ancestries in t...

The appearance of people associated with the Lapita culture in the South Pacific ~3,000 53 years ago 1 marked the beginning of the last major human dispersal to unpopulated 54 lands, culminating in the settlement of eastern Polynesia ~1,000-700 years ago. 55 However, the genetic relationship of these pioneers to the long established Papuans of 56 the New Guinea region is debated. We report the first genome-wide ancient DNA data 57 from the South Pacific, from four ~2,900 to ~2,500 year old Lapita culture individuals 58 from Vanuatu and Tonga, and co-analyze them with new data from 356 present-day 59 Oceanians. Today, all indigenous people of the South Pacific harbor a mixture of 60 ancestry from Papuans and a population of East Asian origin that is a statistical match 61 to the ancient Lapita individuals. Most analyses have interpreted the ubiquitous Papuan 62 ancestry in the region today-at least 25%-as evidence that the first humans to reach 63 Remote Oceania were derived from mixtures near New Guinea prior to the Lapita 64 expansion into Remote Oceania. Our results refute this scenario, as none of the 65 geographically and temporally diverse Lapita individuals had detectable Papuan 66 ancestry. These results imply later major human population movements, which spread 67 Papuan ancestry through the South Pacific after the islands' first peopling. 68 69

Archaeology in Oceania

Nature, 2021

Archaeological data indicate that Near Oceania, which includes New Guinea, the Bismarck archipelago and the Solomon Islands, was peopled around 45 thousand years ago (ka) 5 .The rest of the Pacific-known as Remote Oceania, and including Micronesia, Santa Cruz, Vanuatu, New Caledonia, Fiji and Polynesia-was not settled until around 35 thousand years later. This dispersal, associated with the spread of Austronesian languages and the Lapita cultural complex, is thought to have started in Taiwan around 5 ka, reaching Remote Oceania by about 0.8-3.2 ka 6. Although genetic studies of Oceanian populations have revealed admixture with populations of East Asian origin 7-13 , attributed to the Austronesian expansion, questions regarding the peopling history of Oceania remain. It is also unknown how the settlement of the Pacific was accompanied by genetic adaptation to island environments, and whether archaic introgression facilitated this process in Oceanian individuals, who present the highest levels of combined Neanderthal and Denisovan ancestry worldwide 14-17. We report here a whole-genome-based survey that addresses a wide range of questions relating to the demographic and adaptive history of Pacific populations. Genomic dataset and population structure We sequenced the genomes of 317 individuals from 20 populations spanning a geographical transect that is thought to underlie the peopling history of Near and Remote Oceania (Fig. 1a and Supplementary Note 1). These high-coverage genomes (around 36×) were

The debate concerning the origin of the Polynesian speaking peoples has been recently reinvigorated by genetic evidence for secondary migrations to western Polynesia from the New Guinea region during the 2nd millennium BP. Using genome-wide autosomal data from the Leeward Society Islands, the ancient cultural hub of eastern Polynesia, we find that the inhabitants' genomes also demonstrate evidence of this episode of admixture, dating to 1,700–1,200 BP. This supports a late settlement chronology for eastern Polynesia, commencing ~1,000 BP, after the internal differentiation of Polynesian society. More than 70% of the autosomal ancestry of Leeward Society Islanders derives from Island Southeast Asia with the lowland populations of the Philippines as the single largest potential source. These long-distance migrants into Polynesia experienced additional admixture with northern Melanesians prior to the secondary migrations of the 2nd millennium BP. Moreover, the genetic diversity of mtDNA and Y chromosome lineages in the Leeward Society Islands is consistent with linguistic evidence for settlement of eastern Polynesia proceeding from the central northern Polynesian outliers in the Solomon Islands. These results stress the complex demographic history of the Leeward Society Islands and challenge phylogenetic models of cultural evolution predicated on eastern Polynesia being settled from Samoa. The cultural and linguistic unity of the islands and atolls of the central Pacific was first documented in detail by Johann Reinhold Forster, a naturalist on James Cook's second voyage of discovery to the Pacific (1772–1775). He suggested that the similarity of the languages spoken there, now known as Polynesian, reflected a comparatively shallow time-depth since their dispersal 1. Forster's seminal comparative study of Austronesian languages identified the lowland region of the Philippines in Island Southeast Asia (ISEA) as the ultimate source for the Polynesian languages and proposed a long-distance migration from there by the ancestors of today's Polynesian speakers. This appeared to be the only explanation for the striking difference in phenotype that he observed between the peoples of the central Pacific and those of the intervening region, which is now known as Melanesia. Herein, the terms Melanesia and Micronesia are used in their geographical sense. We use the term Polynesia to include all islands and atolls whose inhabitants speak Polynesian languages, including 23 found throughout Melanesia and Micronesia, referred to as outlier Polynesia (Fig. 1a). Separating the demographic histories of Polynesia and Melanesia became difficult to sustain with developments in archaeology during the second half of the 20th century. These established that the settlement of south

Scientific reports, 2018

The debate concerning the origin of the Polynesian speaking peoples has been recently reinvigorated by genetic evidence for secondary migrations to western Polynesia from the New Guinea region during the 2nd millennium BP. Using genome-wide autosomal data from the Leeward Society Islands, the ancient cultural hub of eastern Polynesia, we find that the inhabitants' genomes also demonstrate evidence of this episode of admixture, dating to 1,700-1,200 BP. This supports a late settlement chronology for eastern Polynesia, commencing ~1,000 BP, after the internal differentiation of Polynesian society. More than 70% of the autosomal ancestry of Leeward Society Islanders derives from Island Southeast Asia with the lowland populations of the Philippines as the single largest potential source. These long-distance migrants into Polynesia experienced additional admixture with northern Melanesians prior to the secondary migrations of the 2nd millennium BP. Moreover, the genetic diversity of ...

The American Journal of Human Genetics, 2014

Archaeology, linguistics, and existing genetic studies indicate that Oceania was settled by two major waves of migration. The first migration took place approximately 40 thousand years ago and these migrants, Papuans, colonized much of Near Oceania. Approximately 3.5 thousand years ago, a second expansion of Austronesian-speakers arrived in Near Oceania and the descendants of these people spread to the far corners of the Pacific, colonizing Remote Oceania. To assess the female contribution of these two human expansions to modern populations and to investigate the potential impact of other migrations, we obtained 1,331 whole mitochondrial genome sequences from 34 populations spanning both Near and Remote Oceania. Our results quantify the magnitude of the Austronesian expansion and demonstrate the homogenizing effect of this expansion on almost all studied populations. With regards to Papuan influence, autochthonous haplogroups support the hypothesis of a long history in Near Oceania, with some lineages suggesting a time depth of 60 thousand years, and offer insight into historical interpopulation dynamics. Santa Cruz, a population located in Remote Oceania, is an anomaly with extreme frequencies of autochthonous haplogroups of Near Oceanian origin; simulations to investigate whether this might reflect a pre-Austronesian versus Austronesian settlement of the island failed to provide unequivocal support for either scenario.

Recent work on autosomal DNA genetic variation across Southeast Asia suggests that genetic diversity largely reflects Pleistocene colonization by modern humans, and was not influenced to any significant degree by major cultural and linguistic changes during the mid-to-late Holocene (roughly, from ~5,000 years ago to the present). These results seemingly show that the spread of Austronesian languages across Island Southeast Asia was not associated with population movements that were significant enough to affect the overall phylogeny of the autosomal DNA tree. Consequently, the spread of genes is not significantly linked to the spread of languages in Island Southeast Asia; each represents different processes of different antiquity.

There are two very different interpretations of the prehistory of Island Southeast Asia (ISEA), with genetic evidence invoked in support of both. The “out-of-Taiwan” model proposes a major Late Holocene expansion of Neolithic Austronesian speakers from Taiwan. An alternative, proposing that Late Glacial/postglacial sea-level rises triggered largely autochthonous dispersals, accounts for some otherwise enigmatic genetic patterns, but fails to explain the Austronesian language dispersal. Combining mitochondrial DNA (mtDNA), Y-chromosome and genome-wide data, we performed the most comprehensive analysis of the region to date, obtaining highly consistent results across all three systems and allowing us to reconcile the models. We infer a primarily common ancestry for Taiwan/ISEA populations established before the Neolithic, but also detected clear signals of two minor Late Holocene migrations, probably representing Neolithic input from both Mainland Southeast Asia and South China, via Taiwan. This latter may therefore have mediated the Austronesian language dispersal, implying small-scale migration and language shift rather than large-scale expansion.

2022

SUMMARYThe Vanuatu archipelago served as a gateway to Remote Oceania during one of the most extensive human migrations to uninhabited lands, ~3,000 years ago. Ancient DNA studies suggest an initial settlement by East Asian-related peoples that was quickly followed by the arrival of Papuan-related populations, leading to a major population turnover. Yet, there is uncertainty over the population processes and the sociocultural factors that have shaped the genomic diversity of ni-Vanuatu, who present nowadays among the world’s highest linguistic and cultural diversity. Here, we report new genome-wide data for 1,433 contemporary ni-Vanuatu from 29 different islands, including 287 couples. We find that ni-Vanuatu derive their East Asian- and Papuan-related ancestry from the same source populations and descend from relatively synchronous, sex-biased admixture events that occurred ~1,700-2,300 years ago, indicating a peopling history common to all the archipelago. However, East Asian-relat...