Melanesian origin of Polynesian Y chromosomes.
BACKGROUND
Two competing hypotheses for the origins of Polynesians are the 'express-train' model, which supposes a recent and rapid expansion of Polynesian ancestors from Asia/Taiwan via coastal and island Melanesia, and the 'entangled-bank' model, which supposes a long history of cultural and genetic interactions among Southeast Asians, Melanesians and Polynesians. Most genetic data, especially analyses of mitochondrial DNA (mtDNA) variation, support the express-train model, as does linguistic and archaeological evidence. Here, we used Y-chromosome polymorphisms to investigate the origins of Polynesians.


RESULTS
We analysed eight single nucleotide polymorphisms (SNPs) and seven short tandem repeat (STR) loci on the Y chromosome in 28 Cook Islanders from Polynesia and 583 males from 17 Melanesian, Asian and Australian populations. We found that all Polynesians belong to just three Y-chromosome haplotypes, as defined by unique event polymorphisms. The major Y haplotype in Polynesians (82% frequency) was restricted to Melanesia and eastern Indonesia and most probably arose in Melanesia. Coalescence analysis of associated Y-STR haplotypes showed evidence of a population expansion in Polynesians, beginning about 2,200 years ago. The other two Polynesian Y haplotypes were widespread in Asia but were also found in Melanesia.


CONCLUSIONS
All Polynesian Y chromosomes can be traced back to Melanesia, although some of these Y-chromosome types originated in Asia. Together with other genetic and cultural evidence, we propose a new model of Polynesian origins that we call the 'slow-boat' model: Polynesian ancestors did originate from Asia/Taiwan but did not move rapidly through Melanesia; rather, they interacted with and mixed extensively with Melanesians, leaving behind their genes and incorporating many Melanesian genes before colonising the Pacific.
Kayser
M
M
Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. kayser@eva.mpg.de
Brauer
S
S
Weiss
G
G
Underhill
P A
PA
Roewer
L
L
Schiefenhövel
W
W
Stoneking
M
M
D001208:Asia / Q000208:ethnology; D002874:Chromosome Mapping; D004272:DNA, Mitochondrial / Q000235:genetics*; D005843:Geography; D006239:Haplotypes; D006801:Humans; D007214:Indonesia / Q000208:ethnology; D008297:Male; D008542:Melanesia; D011114:Polynesia / Q000208:ethnology; D044469:Racial Groups / Q000235:genetics*; D013624:Taiwan / Q000208:ethnology; D014998:Y Chromosome
D004272:DNA, Mitochondrial