2018 Volume 57 Issue 6 Pages 229-237
The emergence of grinding stones with grooves is one of the hallmarks indicating the beginning of bow-and-arrow hunting. In the Japanese islands, grinding stones with grooves appeared from the Incipient Jomon period, which coincides with the timing when arrowheads drastically increased. Although the grinding stone with grooves has been considered to be used as an arrowshaft smoother, its real function is little known so far. The present study conducted a morphometric analysis of a grinding stone with grooves from the Torihama shell mound in Fukui Prefecture, central Japan, in order to better understand the function. To confirm the chronological position of the grinding stone with grooves, we undertook radiocarbon dating of two walnuts (Juglans ailantifolia) recovered from the layer from which the grinding stone with grooves was unearthed. The radiocarbon determinations show 10,160±35BP and 10,070±30BP that are calibrated to 12,030-11,650calBP and 11,770-11,400calBP respectively using IntCal13 calibration curve and OxCal platform. The age range suggests that the grinding stone with grooves from the Torihama shell mound dates from the Pleistocene-Holocene transition. The morphometric analysis of the 3D-data on a groove that most clearly formed on this grinding stone indicates that the groove runs straight and its surface shape shows a small deviation in morphometric values. The high straightness and significantly high morphometric standardization of the groove suggest that the groove was formed due to smoothing of a rod-like material, such as an arrowshaft.
