Initiative in Evolution

The author advances the idea that organisms exert initiative in their own evolution by examining anatomical and experimental evidence for acquired change. He surveys mammalian hair-patterns, epidermal varieties, papillary ridges, flexures of palms and soles, and the evolution of structures such as bursae and the plantar arch, linking these features to muscular action, habit, and innervation. Comparative examples across ungulates, carnivores, primates and other mammals are paired with targeted experiments and discussion of reflex arcs to argue that behavioral and functional use can shape integumentary and musculoskeletal form alongside other evolutionary processes.