  Encompassing regions that were amongst the first inhabited by humans
following the out-of-Africa expansion, hosting populations with the highest
levels of archaic hominid introgression, and including Pacific islands that are
the most isolated inhabited locations on the planet, Oceania has a rich, but
understudied, human genomic landscape. Here we describe the first region-wide
analysis of genome-wide data from population groups spanning Oceania and its
surroundings, from island and peninsular southeast Asia to Papua New Guinea,
east across the Pacific through Melanesia, Micronesia, and Polynesia, and west
across the Indian Ocean to related island populations in the Andamans and
Madagascar. In total we generate and analyze genome-wide data from 981
individuals from 92 different populations, 58 separate islands, and 30
countries, representing the most expansive study of Pacific genetics to date.
In each sample we disentangle the Papuan and more recent Austronesian
ancestries, which have admixed in various proportions across this region, using
ancestry-specific analyses, and characterize the distinct patterns of
settlement, migration, and archaic introgression separately in these two
ancestries. We also focus on the patterns of clinically relevant genetic
variation across Oceania--a landscape rippled with strong founder effects and
island-specific genetic drift in allele frequencies--providing an atlas for the
development of precision genetic health strategies in this understudied region
of the world.
