Methodological Advances in Studying Postnatal Locomotor Development

One crucial characteristic which sets animals apart from most other forms of life is the capability of quick locomotion. Yet moving around does not always come easy: some animals are better at it than others, and common research tools in the field of locomotor biomechanics occasionally fail to quantify subtle differences. For example, during early development, variability in locomotor patterns is high, faults and instabilities are common, but maturation is quick, which is a challenging context for comparative biomechanics. In this project, I set out to expand our methodological capabilities for developmental, comparative biomechanics. The thesis covers kinematics (how animals move) and kinetics (why they move). Based on the observation that locomotor patterns are often repetitive, and applying probabilistic, predictive models which incorporate variability, I spotlight the most fragile of newborn animals: those who are born with particularly low weight. My primary model system are piglets, where low birth weight is common due to increasing litter sizes in commercial breeding. The applied methods (Fourier analysis, probabilistic statistics) are exapted from other fields, thus not novel, but rarely applied to quantitative biomechanics to date. I also highlight limitations and quantify commonly accepted inaccuracies of existing inverse dynamic methods. The case of piglet locomotion can demonstrate how the exapted tools enable unprecedented detail in the analysis of locomotor biomechanics. In particular, I can confirm that low birth weight piglets are fully capable of normal locomotion, and I precisely quantify how their development is halted shortly after birth. This provides some important constraints for the evaluation of coping strategies in commercial farming. Besides, the methodological advances which I present in detail enable a whole new set of research questions for different contexts, within the field of locomotor biomechanics and beyond.