Phase-Shifted Adaptive Trajectories in Primate Trait Evolution

This working paper introduces Phase-Shifted Adaptive Trajectories as a conceptual moving-optimum comparative framework for the study of selected primate trait complexes. The framework conceptualizes hominin and non-human primate lineages as multivariate trajectories navigating high-dimensional adaptive space, tracking partially shared and partially lineage-specific moving optima shaped by ecological, dietary, locomotor, and social drivers. A central operational concept is the estimation of phase offsets (τ), defined as temporal lags between shifts in inferred adaptive drivers or optima and observed phenotypic responses in trait complexes. To ground this framework, a minimum viable pilot focused on the craniofacial-dietary complex is proposed. The manuscript does not report new empirical data and has not been peer-reviewed. It is released as a working paper for public archiving, timestamping, and expert feedback. The framework explicitly avoids teleological interpretations and scalar rankings of primate species. Extant primates are used strictly as comparative referents, while reticulation in late Homo is treated as a methodological boundary condition requiring network-aware interpretation.