title: The origins and genetic distinctiveness of the Chamorros of the Marianas Islands: an mtDNA perspective.
abstract: BACKGROUND
  Archaeological and linguistic evidence suggests the Marianas Islands were settled around 3,600 years before present (ybp) from Island Southeast Asia (ISEA). Around 1,000 ybp latte stone pillars and the first evidence of rice cultivation appear in the Marianas. Both traditions are absent in the rest of prehistoric Oceania.
  
  
  OBJECTIVE
  To examine the genetic origins and postsettlement gene flow of Chamorros of the Marianas Islands.
  
  
  METHODS
  To infer the origins of the Chamorros we analyzed ∼360 base pairs of the hypervariable-region 1 (HVS1) of mitochondrial DNA from 105 Chamorros from Guam, Rota, and Saipan, and the complete mitochondrial genome of 32 Guamanian Chamorros, and compared them to lineages from ISEA and neighboring Pacific archipelagoes from the database.
  
  
  RESULTS
  Results reveal that 92% of Chamorros belong to haplogroup E, also found in ISEA but rare in Oceania. The two most numerous E lineages were identical to lineages currently found in Indonesia, while the remaining E lineages differed by only one or two mutations and all were unique to the Marianas. Seven percent of the lineages belonged to a single Chamorro-specific lineage within haplogroup B4, common to ISEA as well as Micronesia and Polynesia.
  
  
  CONCLUSIONS
  These patterns suggest a small founding population had reached and settled the Marianas from ISEA by 4,000 ybp, and developed unique mutations in isolation. A second migration from ISEA may have arrived around 1,000 ybp, introducing the latte pillars, rice agriculture and the homogeneous minority B4 lineage.
authors.affiliation: Department of Anthropology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA. miguel_vilar@hotmail.com
authors.forename: Miguel G
authors.initials: MG
authors.lastname: Vilar
authors.forename: Chim W
authors.initials: CW
authors.lastname: Chan
authors.forename: Dana R
authors.initials: DR
authors.lastname: Santos
authors.forename: Daniel
authors.initials: D
authors.lastname: Lynch
authors.forename: Rita
authors.initials: R
authors.lastname: Spathis
authors.forename: Ralph M
authors.initials: RM
authors.lastname: Garruto
authors.forename: J Koji
authors.initials: JK
authors.lastname: Lum
mesh_terms: D004272:DNA, Mitochondrial / Q000235:genetics*; D004641:Emigration and Immigration; D051456:Gene Flow; D006141:Guam; D006239:Haplotypes; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D044468:Native Hawaiian or Pacific Islander / Q000235:genetics*; D010802:Phylogeny; D011114:Polynesia
chemical_list: D004272:DNA, Mitochondrial