Dental scratches and handedness in East Asian Early Pleistocene hominins

The current study aims to characterise dental scratches found on an East Asian hominin upper left central incisor (I1) and lower left lateral incisor (I2) from the Early Pleistocene (Meipu site, Yunxian County), and infer the preference for handedness of these two individuals by quantifying the orientation of dental scratches. The labial surfaces of these two teeth were observed and imaged using light microscopes and/or scanning electron microscope under different magnifications (5–70×). The angle, width and length of each dental scratch was measured and analysed. The dental scratches described and quantified on the labial enamel surface of Meipu I1 and I2 fit the description of cutmarks caused by ‘stuff and cut’ behaviour. Most scratches are oriented in the right oblique direction, averaging 47.11 degrees in I1 and 44.60 degrees in I2. This result indicates preference for the right hand as the dominant one in holding a tool during ‘stuff and cut’ behaviours. This is the earliest reported ‘stuff and cut’ behaviour and inferred right-handedness in East Asia. It fills a temporal gap between the earliest known example in the African Early Pleistocene (~1.8 Ma) and the next known instance in the European Middle Pleistocene. This is also the first time the ‘stuff and cut’ behaviour and right-handedness has been reported in a hominin assigned to Homo erectus sensu lato.