In these lectures, Arie Verhagen presents a version of cognitive linguistics that adheres to both the generalization and cognitive commitments that characterized the field from the start, and a biological commitment: understanding language as adaptive behavior of (human) organisms in the niche(s) that they inhabit. Drawing on the model of biological explanation (“Tinbergen’s four why’s”), Verhagen shows how proximate (individual level) and ultimate (population level) explanations apply to several features of language, shedding new light on basic notions like conventionality and entrenchment, norms/rules and habits, etc., and their causal connections. Topics include the relation between language, culture, and thinking, the role of language in social cognition and narrative, the evolution of sound structure and grammar, semantic change, and more.