【考古学】中国で最古のヒト族の存在を示す証拠となるか

A largely continuous artefact sequence in Shangchen, China, which has been dated to between 1.3 and around 2.1 million years ago, is reported in a paper published online this week in Nature. The findings suggest that there may have been a hominin presence outside Africa earlier than previously thought.

The earliest evidence of hominins outside of Africa comes from Dmanisi, Georgia, where tools and bones of Homo erectus date as far back as 1.85 million years ago. Other early hominin fossils found in China and Java date to between 1.5 and 1.7 million years ago, although there have been persistent claims for evidence of hominin activity that is older than 2 million years.

Zhaoya Zhu and colleagues describe 82 flaked and 14 unflaked stones from the Early Pleistocene found at Shangchen in the Chinese Loess Plateau. Among these stones were cores, flakes, scrapers, points and borers, and picks, which suggest evidence of early tools. The authors also identified two pieces of hammerstones with percussion damage. Excavation around this area revealed core and flake tools along with a lower jaw fragment of a deer, as well as bovid (a cloven-hoofed ruminant mammal)and other fossil bone fragments.

The authors show that this sequence has 17 artefact-bearing layers. The stone artefacts were mostly found in 11 layers, which developed in a warm and wet climate; however, artefacts were found in only six loess layers. Loess is a silt-sized sediment formed by the accumulation of wind-blown dust, indicating a colder and drier climate. The authors suggest that this pattern is consistent with a similar artefact sequence found in Tajikistan. In addition, the authors note that the 17 layers span a long period, about 0.85 million years, and indicate that there may have been repeated, but not necessarily continuous, hominin occupation of the Chinese Loess Plateau between 1.3 and 2.1 million years ago.