Emergence of kinship structures and descent systems: multi-level evolutionary simulation and empirical data analyses

In clan societies, people are categorised into several cultural groups, so-called clans, within which they believe to share common ancestors. Clan attributions provide certain rules for marriage and descent. Anthropologists have revealed several kinship structures and their corresponding cultural characteristics, following such rules. We previously introduced an agent-based model of kinship structures. Here, we propose a simplified model in which competing societies evolve. The societies themselves comprise multiple evolving families with parameters for cultural traits and mate preferences. These values determine with whom each family cooperates and competes, and they mutate when transmitted to a new generation. The growth rate of each family is determined by the number of cooperators and competitors. Through this multi-level evolution, family traits and preferences diversify to form clusters that possess the properties of clans. Subsequently, kinship structures emerge, including dual organisation and generalised or restricted exchange, as well as patrilineal, matrilineal, and double descent systems. These structures depend on the necessity of cooperation and the strength of mating competition, which are also estimated analytically. Finally, statistical analysis based on the Standard Cross-Cultural Sample, a global ethnographic database, empirically verify theoretical results. Such collaboration between theoretical and empirical approaches will unveil universal features in anthropology.