Various disciplines, including evolutionary biology, anthropology, archaeology, and psychology, have studied the evolution of rituals. Archaeologists have typically argued that burial practices are one of the most prominent manifestations of ritual practices in the past and have explored various aspects of burial practices, including burial directions. One of the important hypotheses on the cultural evolution of burial practices in Japan is the kitamakura hypothesis, which claims that burial directions (including Kofuns and current burials) were intended to be oriented toward the (...) north after the Kofun period under the influence of Confucianism or Buddhism. This hypothesis would be more plausible if burial directions were not oriented northward before the Kofun period. This research focused on the burial directions in the northern Kyūshū area of the Yayoi period, i.e., the directions of the kamekan jar burials. The results are almost consistent with the hypothesis, although one notable exception is found, and its possible interpretations and implications are discussed. (shrink)

The causes of prehistoric inter-group violence have been a subject of long-standing debate in archaeology, an- thropology, 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 hy- pothesis. 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. (shrink)

The evolution of altruism in human societies has been intensively investigated in social and natural sciences. A widely acknowledged recent idea is the “parochial altruism model,” which suggests that inter- group hostility and intragroup altruism can coevolve through lethal intergroup conflicts. The current article critically examines this idea by reviewing research relevant to intergroup conflicts in human evolutionary history from evolutionary biology, psychology, cultural anthropology, and archaeology. After a brief intro- duction, section 2 illustrates the mathematical model of parochial altruism (...) and some critiques of the model and its interpretation, primarily from an evolutionary biology point of view. Section 3 delves into the archaeological evidence of prehistoric intergroup conflicts in the Japanese archipelago’s Jomon and Yayoi periods, Europe’s Mesolithic period, and North America’s Pacific period as counter examples of the paro- chial altruism model. In section 4, the ethnographies of intergroup relationships and conflicts reveal that intergroup relationships in many ethnic groups are not as simple as the assumption in the mathematical model of parochial altruism. In section 5, we outline psychological research on intergroup conflicts which suggest that intergroup hostility and ingroup altruism are not necessarily correlated. In conclusion, we argue that the assumption and parameter settings of the parochial altruism model are inconsistent with empirical data. (shrink)