关键词: 丹江口库区;薄刃斧;技术;形态;适应策略

Abstract: Currently, toolkits containing Acheulean technological elements have been found in several regions of China, including the Bose and Luonan Basins. Compared with the core and flake technology of the Oldowan, this is a new complex showing the enhancement of the technological and cognitive abilities of early humans. This implies the potential diversity and complexity of human evolution in the Middle Pleistocene of China. This paper focuses on the detailed analysis of 18 cleavers retrieved from the Danjiangkou Reservoir Region. Danjiangkou Reservoir Region is located at the southern edge of the Qinling Mountains which is considered to be the boundary between North and South China, and it is fed by the Han River, the largest tributary of the Yangtze River. During Pleistocene times, this area had a relatively stable subtropical environment with abundant plant and animal resources suitable for hominid subsistence. Comprehensive chronological analyses indicate that LCTs in this region have persisted for a long period, from the late Early Pleistocene to the Late Pleistocene. Raw materials for making cleavers are cobbles from the nearby river banks. In total, three local raw materials were employed. Quartz phyllite accounts for 50%, trachyte for 44%, and quartz for 6% of the cleavers in this sample. These different proportions indicate a clear preference for certain raw materials that corresponds with the quality of each rock type. The cobbles in this region are generally well-rolled oval shapes. The size of pebbles and cobbles in the gravels varies, with lengths concentrated in 2-15 cm range, which has a big influence on the flaking methods. The minimum and maximum length of cleavers in the sample is 128.73mm and 235.70mm, and the average length is 179.07mm. Different kinds of blanks were exploited by these hominids to make cleavers. Large flakes and cobbles were equally used, 50% respectively. Among the large flake blanks, free hand percussion, bipolar technique and throwing technique are recognized, showing that various flaking techniques were used depending on the raw material. Cobbles used to make the cleavers were well selected, as they tend to be elongated oval or flat shapes, which can provide suitable platforms and angles for direct invasive flaking of the laterals. The size of the selected cobbles was more or less uniform, a size comfortable for holding in the hand. To explore the intensity of shaping, the numbers of primary and secondary scars are counted. There is a clear pattern that the average number of secondary shaping scars (10.4) is higher than the average number of primary shaping scars (4.5), which indicates that more shaping was conducted to refine the edges than to shape the body of the piece. And the total average number of scars (14.9) is relatively low compared with most western Acheulean cleavers (the lowest average scar number is 14.7 for the Ternifine site, North Africa), which manifests a least-effort strategy in shaping and/or a property of the specific raw materials. On the topic of shaping patterns, nine cleavers are partly bifacial (50%), seven are bifacial (38.9%) and two are unifacial (11.1%). And the average proportion of shaping for the distal end (both edges) is 90.3%, for the middle portion is 62.5%, and for the proximal end is 33.3%, reflecting that the distal end is the functional part of the tool. The formation of distal functional edges is done in different ways: First, similar with typical African cleavers, the cleaver bit was formed by the intersection of large dorsal scars and the ventral surface, or sometimes the dorsal face can also be cortical (N=4/18); Second, similar to European cleavers, they were made by the tranchet technique with the tranchet flake scars parallel to the cleaver bit (N=7/18); Third, as an adaptation to the local raw material, they were made by intentional shaping of the distal edge, with the blow parallel to the main axe (N=7/18). Analysing morphology using Roe’s shape diagram method shows that there is no standardized pattern of the shape of cleavers, but that they display much variability. A Principal Component Analysis indicates that raw material and the type of shaping do not have a close relationship with morphological variation. However, it appears that blank type may play an important role in this morphological variation. This is displayed in the greater breadth and thickness values of cobble blanks than flake blanks, which is consistent with the metric data. Through the comprehensive consideration of the features of cleavers, we infer that the people in the Danjiangkou Reservoir Region possessed the technological ability of manufacturing cleavers. Moreover, this implies that they were also applying flexible adaptive strategies according to the local raw materials, palaeoenvironment, etc. This indicates a similarity of cognitive abilities between early humans in the East and West.

Key words: Danjiangkou Reservoir; Cleaver; Technology; Morphology; Adaptive strategy