Individual_Development_And_Interaction_Theory focus on micro-level processes involving individual cognitive development, social interaction, and the relationship between biology, language, and behaviour. These theories examine how individuals develop cognitively and socially throughout their lives, from Piaget's developmental stages to aging theories like disengagement theory. Symbolic interactionism emphasises how individuals create meaning through social interaction and shared symbols. The Sapir-Whorf hypothesis explores how language shapes thought and perception, while sociobiology investigates biological foundations of social behaviour. Cornucopian theory represents optimistic views of human adaptability and innovation, and multiple-nuclei theory examines urban development patterns from a more localised perspective. Despite their diversity, these theories share an emphasis on individual-level processes, whether cognitive, linguistic, biological, or interactional, and how these micro-level phenomena contribute to broader social patterns and human adaptation to environmental challenges.