Modeling Paradigms for Complex Biological Motion: From the Water-Carrying Case to an Evolution-Phylogeny Progressive-Dimensionality-Reduction Framework

This is a conceptual theoretical paper introducing a new modeling framework for biological motion. Quantitative numerical validation and case simulations will be presented in follow-up independent work.Modeling the motion of the human body interacting with external loads is a foundational topic in biomechanics, rehabilitation science, and the science of exercise. Using the single-person carriage of a filled water bottle as a unifying case, this paper surveys the evolution of modeling from classical rigid-body mechanics to the modern musculoskeletal biomechanics centered on Hill-type muscle models. It argues that the two generations of paradigms share a reductionist modeling strategy of “decomposition followed by closure through auxiliary assumptions,” and are jointly constrained by multiple engineering limits in in-vivo observation, individual calibration, and high-dimensional coupled solving. To address the dimensionality explosion and the subjectiveness of variable selection in modeling higher organisms, this paper proposes an evolution-phylogeny progressive-dimensionality-reduction modeling paradigm: the temporal order of evolution serves as the criterion for introducing variables incrementally, survival feasibility acts as a first-level hard constraint, and the model is constructed stage by stage from the simple to the complex, thereby decomposing an ultra-high-dimensional, strongly coupled global solving problem into a sequence of low-dimensional subproblems that can be verified stage by stage. On this basis, the paper further advances a long-term mechanistic hypothesis of cell–tissue–organ multilayer-weight emergence, and analyzes the nonlinear trade-off between investment, difficulty, and output inherent in general-purpose modeling of complex systems. This paper is positioned as a programmatic, openly discussed study intended to provoke interdisciplinary and cross-paradigm academic debate.