Y chromosomal evidence for the origins of oceanic-speaking peoples

Abstract

A number of alternative hypotheses seek to explain the origins of the three groups of Pacific populations—Melanesians, Micronesians, and Polynesians—who speak languages belonging to the Oceanic subfamily of Austronesian languages. To test these various hypotheses at the genetic level, we assayed diversity within the nonrecombining portion of the Y chromosome, which contains within it a relatively simple record of the human past and represents the most informative haplotypic system in the human genome. High-resolution haplotypes combining binary, microsatellite, and minisatellite markers were generated for 390 Y chromosomes from 17 Austronesian-speaking populations in southeast Asia and the Pacific. Nineteen paternal lineages were defined and a Bayesian analysis of coalescent simulations was performed upon the microsatellite diversity within lineages to provide a temporal aspect to their geographical distribution. The ages and distributions of these lineages provide little support for the dominant archeo-linguistic model of the origins of Oceanic populations that suggests that these peoples represent the Eastern fringe of an agriculturally driven expansion initiated in southeast China and Taiwan. Rather, most Micronesian and Polynesian Y chromosomes appear to originate from different source populations within Melanesia and Eastern Indonesia. The Polynesian outlier, Kapingamarangi, is demonstrated to be an admixed Micronesian/ Polynesian population. Furthermore, it is demonstrated that a geographical rather than linguistic classification of Oceanic populations best accounts for their extant Y chromosomal diversity. T HE island populations of the Pacific Ocean have historically been divided, on the basis of geography and culture, into Polynesians, Micronesians, and Melanesians (Bellwood 1989). According to this system Polynesians occupy islands within a triangle defined by apices at New Zealand, Hawaii, and Rapanui (Easter Island). Melanesians occupy the islands farther to the west (including Papua New Guinea), and Micronesians occupy the coral atolls that lie to the north of Melanesia. Within Melanesia and Micronesia lie a number of islands whose populations seem to share more cultural (including linguistic) features with Polynesians than with their geographical neighbors; these “Polynesian outliers” are thought to originate from recent back migrations from Polynesia (Bellwood 1989). …