Isochron 26Al/10Be burial dating of Xihoudu: Evidence for the earliest human settlement in northern China

Abstract

The mainstream school of human evolution posits that Homo erectus was the earliest species to leave Africa at ∼1.85 million years (Ma) ago. Recent discoveries from the Shangchen loess-palaeosol sequence near the Lantian hominid site in northern China, however, show lithic artifacts up to 2.12 Ma, pre-dating the fossil record of H. erectus. Here we apply the recently established isochron 26Al/10Be burial dating, whose reliability has been verified by intercomparison with 40Ar/39Ar dating, to two locations at the Palaeolithic site of Xihoudu ∼100km east of Shangchen. The results show that the stone tools found within river gravels there are 2.43±0.06 Ma (1σ) old, making them the earliest radio-isotopically dated evidence for human occupation in Eurasia. The new date is supported by relative dating of the associated fauna, by consistent simple burial ages of quartz sand from deep cores, and by agreement between the two isochrons. Although the validity of the Xihoudu artifacts has been previously debated because of marked fluvial abrasion, there is clear evidence of intentional flaking. In particular, in addition to two cores with small amounts of cortex, a number of flakes lack original rock cortex, which indicate multiple and sustained removals that do not occur naturally. The great antiquity of the Xihoudu artifacts renders firm support to an earlier “Out of Africa I” that approaches the emergence of the genus Homo and the Oldowan industry.