Functional insights from an exploration of the inner structure of the patella: new perspectives for the study of the hominin fossil record

Abstract

– This contribution is a short review of the func tional significance of the patella in extant catarrhines and extinct hominins and of current functional, adaptive and evo -lutionary-related questions concerning the fossil hominin record. The patella plays a key functional role in the knee joint and thus reflects habitual postural and locomotion modes. However, patellar remains are rare in the hominin fossil record and it is still unclear whether and how their differences in shape and proportions compared to extant humans affect knee kinesiology. Here, we illustrate with a first example from a sample of human, Pan , Papio and Neanderthal patellae that the development of a “whole-bone” endostructural analysis has the potential to provide relevant functional information for reconstructing the knee loading environment in fossil taxa, combined, whenever necessary, with a subsampling approach. This method relies on the plastic nature of the cortical and trabecular bony tissues and the modelling and remodelling dynamics during life to adjust structurally to the site-specific loading environment. This kind of information would bring new contributions not only to ongoing discussions on the evolutionary forces that shaped the knee joint in association with postural and locomotor adaptations, but also to the tentative taxonomic identification of isolated fossil specimens.