【進化】オーストラリア内陸部の乾燥地帯にヒトが移住したことを示す最古の証拠

Humans had settled in Australia’s arid interior by around 49,000 years ago, 10,000 years earlier than previously reported, according to new archaeological evidence published online in Nature this week. The study suggests that people settled in the arid interior within a few millennia of arriving on the continent and shows that they developed key technologies and cultural practices much earlier than previously thought for Australia and Southeast Asia.

Humans arrived in Australia about 50,000 years ago. However, the timing of both their settlement of the continent’s arid interior and the development of technologically innovative material culture (such as relatively advanced stone tools), along with the degree to which they interacted with now-extinct giant animals (megafauna), are still debated within the scientific community.

Giles Hamm and colleagues analysed material discovered during an excavation at Warratyi rock shelter in the Flinders Ranges, South Australia. They show that humans occupied the site from 49,000 to 46,000 years ago and that objects recovered from the various layers of sediment represent the earliest-known use in Australia of various notable technologies. These include worked bone tools (40,000-38,000 years ago), backed stone tools (30,000-24,000 years ago), and the use as pigments of red ochre (49,000-46,000 years ago) and gypsum (40,000-33,000 years ago).

The authors also describe evidence of human co-existence with Diprotodon optatum, the largest-known marsupial, and the giant bird Genyornis newtoni. The authors note this discovery is the only reliably dated, well-stratified record of extinct Australian megafauna associated with artefacts older than 46,000 years, and the clearest evidence yet for their interaction with humans.