Ancient voyaging and Polynesian origins

Abstract

The "Polynesian motif" defines a lineage of human mtDNA that is restricted to Austronesian-speaking populations and is almost fixed in Polynesians. It is widely thought to support a rapid dispersal of maternal lineages from Taiwan ~4000 years ago (4 ka), but the chronological resolution of existing control-region data is poor, and an East Indonesian origin has also been proposed. By analyzing 157 complete mtDNA genomes, we show that the motif itself most likely originated >6 ka in the vicinity of the Bismarck Archipelago, and its immediate ancestor is >8 ka old and virtually restricted to Near Oceania. This indicates that Polynesian maternal lineages from Island Southeast Asia gained a foothold in Near Oceania much earlier than dispersal from either Taiwan or Indonesia 3-4 ka would predict. However, we find evidence in minor lineages for more recent two-way maternal gene flow between Island Southeast Asia and Near Oceania, likely reflecting movements along a "voyaging corridor" between them, as previously proposed on archaeological grounds. Small-scale mid-Holocene movements from Island Southeast Asia likely transmitted Austronesian languages to the long-established Southeast Asian colonies in the Bismarcks carrying the Polynesian motif, perhaps also providing the impetus for the expansion into Polynesia.

Figure 1

Map Showing China, Taiwan, MSEA, ISEA, Near Oceania, and Remote Oceania Sampling locations and sample sizes for HVS-I sequences used in the Surfer analyses are indicated. MSEA denotes Mainland Southeast Asia; ISEA denotes Island Southeast Asia.

Figure 2

Chronology of Human mtDNA Haplogroup B4, with a Focus on the Austronesian-Specific B4a1a Clade Branch lengths were estimated via maximum likelihood (ML) and a time-dependent molecular clock obtained from four ML trees, with data from different regions within B4a1a (overall data, Taiwan, ISEA, and Bismarck Archipelago only). ISEA denotes Island Southeast Asia; PM denotes Polynesian motif.

Figure 3

Spatial Frequency Distributions of HVS-1 Variation Created by using the Kriging Algorithm of the Surfer Package (A) Paragroup B4a1a^∗ (excluding B4a1a1). (B) Paragroup B4a1a1^∗ (excluding B4a1a1a). (C) Haplogroup B4a1a1a (defined by the Polynesian motif).

Figure 4

B4a1a Age Estimates and Putative Prehistoric Processes Overlapping ranges of the 95% confidence intervals of the different age estimates within B4a1a and estimated times of several hypothetical events in archaeology and paleoclimatology are indicated. Details of age estimates within the B4a1a clade are presented in Table 1 and Tables S3 and S8.