The causes of prehistoric inter-group violence have been a subject of long-standing debate in archaeology, anthropology, and other disciplines. Although population pressure has been considered as a major factor, due to the lack of available prehistoric data, few studies have directly examined its effect so far. In the present study, we used data on skeletal remains from the middle Yayoi period of the Japanese archipelago, where archaeologists argued that an increase of inter-group violence in this period could be explained by a population-pressure hypothesis. We quantitatively examine the effect of population pressure on the frequency of inter-group violence by compiling an exhaustive data set. We collected demographic information based on burial jars (kamekan) and the frequency of violence based on the ratio of injured individuals. The results are consistent with the hypothesis, i.e., high population density can promote inter-group violence.

史前群体间暴力的原因一直是考古学、人类学和其他学科长期争论的主题。尽管人口压力被认为是一个主要因素，但由于缺乏可用的史前数据，到目前为止，很少有研究直接考察其影响。在本研究中，我们使用了日本列岛弥生中期的骨骼遗骸数据，考古学家认为，这一时期群体间暴力的增加可以用人口压力假说来解释。我们通过编制详尽的数据集，定量研究人口压力对群体间暴力频率的影响。我们收集了基于墓葬罐 ( kamekan) 的人口统计信息) 和基于受伤人数比例的暴力频率。结果与假设一致，即高人口密度可以促进群体间暴力。