Warfare and Migration in Human Prehistory: Spatial and Kinship Determinants of Inter-group Interaction and Dispersal

Theoretical and computational accounts of prehistoric warfare and migration frequently assume stochastic encounter probabilities of conflict and dispersal among forager groups. This review challenges that assumption. Synthesising ethnographic, archaeological, and ancient-DNA evidence, I demonstrate that both lethal conflict and dispersal in the Late Pleistocene and Early Holocene were systematically constrained by spatial proximity and kinship structure. Distance imposes energetic and informational costs that restrict routine interactions to neighbouring groups, while genealogical relatedness modulates cooperation and violence. Across studies, intergroup conflict concentrates at boundaries between genetically dissimilar communities. Migration follows short-range, kin-biased pathways producing spatial gradients of relatedness. Contradictory findings derive from methodological limitations and do not invalidate the predominant pattern. Recognizing warfare and migration as structured processes clarifies selective pressures shaping cooperation and offers an empirical basis for interpreting localized violence, displacement patterns, and institutional resilience in contemporary populations.