From Attachment to Departure: An Evolutionary-Developmental Theory of Group Attachment and the Emergence of Departure Strategies

This paper develops an evolutionary-developmental theory that explains why humans disproportionately favor long-term group attachment over individual departure ("wandering") after social adversity and how modern ecological change has altered the adaptive landscape for departure strategies. Building on evolutionary psychology, attachment theory, behavioral genetics, and social neuroscience, I argue that human evolution favored neuro‑emotional architectures that strongly penalize separation from primary social groups because the fitness costs of departure were historically extreme. These architectures are instantiated by a multi‑genic network that shapes affiliative motivation, social pain sensitivity, risk tolerance, and valuation of alternative social niches—not by a single "wandering gene." I formalize a conceptual model linking genotype -> neurodevelopment -> affective and cognitive mechanisms -> behavioral strategy, and I derive testable predictions and empirical methodologies (behavioral genetics, neuroimaging, longitudinal cohorts, agent‑based simulations, cross‑cultural analyses). The theory accounts for developmental timing (the late maturation of self‑modeling and future planning), the persistence of attachment despite trauma, and why departure strategies have become more viable and visible in modern societies. I discuss limitations, potential extensions, and implications for clinical practice and social policy. Keywords: group attachment; evolutionary psychology; behavioral genetics; social pain; migration; departure strategy; developmental psychology; social neuroscience