Population Turnover in Remote Oceania Shortly After Initial Settlement

Abstract

SummaryAncient DNA analysis of three individuals dated to ~3000 years before present (BP) from Vanuatu and one ~2600 BP individual from Tonga has revealed that the first inhabitants of Remote Oceania (“First Remote Oceanians”) were almost entirely of East Asian ancestry, and thus their ancestors passed New Guinea, the Bismarck Archipelago, and the Solomon Islands with minimal admixture with the Papuan groups they encountered [1]. However, all present-day populations in Near and Remote Oceania harbor 25-100% Papuan ancestry, implying that there must have been at least one later stream of migration eastward from Near Oceania. We generated genome-wide data for 14 ancient individuals from Efate and Epi Islands in Vanuatu ranging from 3,000-150 BP, along with 185 present-day Vanuatu individuals from 18 islands. We show that people of almost entirely Papuan ancestry had arrived in Vanuatu by 2400 BP, an event that coincided with the end of the Lapita cultural period, changes in skeletal morphology, and the cessation of long-distance trade between Near and Remote Oceania [2]. First Remote Oceanian ancestry subsequently increased via admixture but remains at 10-20% in most islands. Through a fine-grained comparison of ancestry profiles in Vanuatu and Polynesia with diverse groups in Near Oceania, we find that Papuan ancestry in Vanuatu is consistent with deriving from the Bismarck Archipelago instead of the geographically closer Solomon Islands. Papuan ancestry in Polynesia also shows connections to the ancestry profiles present in the Bismarck Archipelago but is more similar to Tolai from New Britain and Tutuba from Vanuatu than to the ancient Vanuatu individuals and the great majority of present-day Vanuatu populations. This suggests a third eastward stream of migration from Near to Remote Oceania bringing a different type of Papuan ancestry.

Sequencing of 53,831 diverse genomes from the NHLBI TOPMed Program

“…In the Amish and other samples, the distribution of IBD segments allows estimates of effective population sizes over the last 300 generations ( Figure 5). The demographic histories are broadly similar between ancestry groups, with the exception of the Amish, who experienced a more extreme bottleneck when moving to the New World, and the Samoans, who have had a smaller effective population size than the East Asian populations from which they separated ~5000 years ago 58,59 . Both non-Amish European ancestry and African ancestry populations appear to have experienced a bottleneck~5-10 generations ago, consistent with moving to the New World, whether through colonization or forced migration.…”

Revisiting ancient DNA insights into the human history of the Pacific Islands

“…We begin by highlighting a philosophical point that guided our writing team in Lipson et al . () and the earlier Skoglund et al . ().…”

“…The second stream involved little exchange with people from the main Solomon Islands (Sheppard ), consistent with the specific relationship of Papuan ancestry in both present‐day and ancient Ni‐Vanuatu to the Papuan ancestry in the Bismarck Archipelago found in both Lipson et al . () and Posth et al . ().…”

“…However, present‐day groups have relatively homogeneous proportions and sources (ultimately from the Bismarck Archipelago) for their Papuan ancestry, plus similar reconstructed average dates of mixture between Papuan and FRO ancestry sources (albeit with some exceptions: Lipson et al . ). This supports the idea of a relatively discrete “second wave” (Blust's “M2”, Forum, p. 206).…”

Direct evidence of an increasing mutational load in humans

“…It is therefore possible that the results presented here, limited to Europe, be generalizable to the rest of the non-Subsaharan human populations. As more ancient DNA from the rest of the world is accumulating [31,32,33], this hypothesis will soon be testable.…”