Human speech is routinely treated as a symbolic, semantic, and pragmatic phenomenon — a domain of meaning, intention, and social coordination. This paper argues that a specific class of speech patterns, termed compensatory-defensive speech, has biological roots in phylogenetically ancient protective systems and may be partially computable. We distinguish this class from ecological defensive speech, in which the same underlying vectors produce proportionate, reversible, contact-preserving responses to real threats. Drawing on polyvagal theory, affective neuroscience, active inference, predictive coding, and attachment theory, we propose that the canonical defensive responses — fight, flight, fawn, and freeze — do not disappear when organisms acquire language. Rather, they can be reorganized into speech forms that preserve their original directional logic: approach-with-force, retreat, submit-to-appease, and immobilization. The paper maps these defensive vectors onto speech-level forms: fight into projection and accusatory discourse, flight into intellectualization and topic-shift, fawn into ingratiating self-erasure, and freeze into vagueness, silence, and epistemic absence. It also proposes criteria for distinguishing ecological from compensatory expression: proportionality, reversibility, and contact-preservation. We integrate allostatic load as the metabolic signature of sustained compensatory defense and treat shame as a predictive comparison between the narrative self-model and internalized social expectations. This framing does not reduce language to biology. It proposes that language is an additional layer over defensive architecture, and that compensatory-defensive speech becomes interpretable — and potentially computable — when biological vectors, predictive shame, and the ecological/compensatory distinction are made explicit. Subsequent papers in the series develop the computational, ontological, and empirical consequences of this framework.