【ゲノミクス】オーストラリアの地域多様性を解明する手掛かりとなる先住民のゲノム

Analysis of more than 100 Aboriginal Australian mitochondrial genomes indicates that the settlement of Australia comprised a single, rapid migration along the coasts that reached southern Australia as early as 49,000 years ago. The findings, reported in the journal Nature this week, suggest that populations of Aboriginal Australians have persisted in distinct geographical areas for almost 50,000 years.

Archaeological evidence indicates that Australia and New Guinea - which were once connected as a single landmass known as Sahul - were initially settled around 50,000 years ago. However, the processes underlying the enormous linguistic and phenotypic diversity within Australia have remained uncertain.

Alan Cooper and colleagues extracted mitochondrial genomes from hair samples collected between the 1920s and 1970s from 111 individuals across three different Aboriginal communities (two in South Australia, one in Queensland). Analysis of these mitogenomes allowed the authors to produce detailed reconstructions of the genetic and historical relationships among Aboriginal Australian groups prior to European settlement. The authors find that from landfall in northern Australia, people spread rapidly around the east and west coasts, meeting in the south around 49,000 to 45,000 years ago. Strong regional patterns of mitochondrial DNA variation indicate the continuous presence of Aboriginal Australian populations in discrete geographical regions dating back around 50,000 years, despite significant cultural and climate changes, such as the widespread aridification and cooling of the Last Glacial Maximum.