Ancient DNA from Guam and the peopling of the Pacific

Abstract

Humans reached the Mariana Islands in the western Pacific by ∼3,500 y ago, contemporaneous with or even earlier than the initial peopling of Polynesia. They crossed more than 2,000 km of open ocean to get there, whereas voyages of similar length did not occur anywhere else until more than 2,000 y later. Yet, the settlement of Polynesia has received far more attention than the settlement of the Marianas. There is uncertainty over both the origin of the first colonizers of the Marianas (with different lines of evidence suggesting variously the Philippines, Indonesia, New Guinea, or the Bismarck Archipelago) as well as what, if any, relationship they might have had with the first colonizers of Polynesia. To address these questions, we obtained ancient DNA data from two skeletons from the Ritidian Beach Cave Site in northern Guam, dating to ∼2,200 y ago. Analyses of complete mitochondrial DNA genome sequences and genome-wide SNP data strongly support ancestry from the Philippines, in agreement with some interpretations of the linguistic and archaeological evidence, but in contradiction to results based on computer simulations of sea voyaging. We also find a close link between the ancient Guam skeletons and early Lapita individuals from Vanuatu and Tonga, suggesting that the Marianas and Polynesia were colonized from the same source population, and raising the possibility that the Marianas played a role in the eventual settlement of Polynesia.

Genomic Insights Into the Demographic History of the Southern Chinese

“…Third, the continuous gene flow between northern and southern China since Holocene shaped the genetic profile of many East Asian populations, especially Han Chinese (Ning et al, 2020;Yang et al, 2020;Wang C. C. et al, 2021;Wang T. et al, 2021). Fourth, the migrants out of southern China since ∼4,000 BP, who carry a shared ancestry putatively related to unsampled farmers from Yangtze River, likely facilitated the diffusion of wet-rice agriculture and language families, such as Austronesian and Austroasiatic languages (Skoglund et al, 2016;Lipson et al, 2018aLipson et al, ,b, 2020McColl et al, 2018;Yang et al, 2020;Pugach et al, 2021;Wang C. C. et al, 2021).…”

Ancient DNA reveals five streams of migration into Micronesia and matrilocality in early Pacific seafarers

“…The ordering of the FRO lineage splits is also important. The fact that the FRO Palau lineage split first cannot be explained by the theory that there was a single First Remote Oceanian spread into the Mariana Islands ( 28 , 38 ), which then gave rise to the other lineages, because in this case, FRO Marianas would have branched first. The theory of a Mariana population being ancestral to all FRO lineages is further challenged by the mitochondrial DNA evidence.…”

“…(M1 to M3) Three streams of FRO migration into Micronesia including a previously unknown lineage. We plotted a statistic measuring affinity to the two previously identified ( 7 , 28 ) lineages FRO SouthwestPacific and FRO Marianas , specifically, f 4 (X, New Guinea Highlanders; Lapita, Unai) against our statistic measuring overall FRO ancestry proportion. All populations from the southwest Pacific and Polynesia fall on a line with a positive slope, implying closer affinity to Lapita than to Unai consistent with the Lapita-associated lineage being the source of their East Asian–associated ancestry (all residuals | Z | < 2 after regression; Fig.…”

“…To test alternative models of population history, we generated genome-wide ancient DNA data for 164 individuals from five archaeological sites and coanalyzed them with published data from two ~2200 BP individuals from Guam ( 28 ). A total of 109 individuals (2800 to 300 BP) were from the Unai and Latte periods in Guam, 46 (600 to 200 BP) from the Latte period in Saipan, and 11 (500 to 300 BP) from Na Island and the nearby Nan Madol site in Pohnpei’s protected lagoon in Central Micronesia ( 20 ).…”

Conservation genomics and systematics of a near‐extinct island radiation

“…One of the most concerning insights from our study of A. hiwae is that the apparent sustained and steep decline in effective population size pre-dates modern anthropogenic threats (Figure 6). This suggests that A. hiwae could already be suffering from the negative impacts of inbreeding depression triggered by the initial human occupation of the archipelago estimated at ~3500 years ago (Carson, 2020;Pugach et al, 2021), which probably led rapidly to habitat changes and predator introduction (Steadman, 2006). Consistent with genomics models of long-term declines in N e (Figure 6) are subfossil bones of nightingale reedwarblers from Tinian, which date to around 2000 years before the present, and the patchy distribution of reedwarblers across the Mariana Islands, which suggest that the nightingale reedwarblers were more widespread before human arrival (Reichel et al, 1992;Steadman, 1999).…”