Kropotkin worked within the framework of 19th century natural science, but his results are just as relevant today as they were then. Moreover, the accuracy of his insights is vindicated by the latest research into complexity theory. Geoffrey West, who was a practicing particle physicist for forty years and is now distinguished professor at the Santa Fe Institute, has achieved some stunning breakthroughs in complexity theory and the mathematical characterization of scaling of biological systems….The growth of every animal is characterized by a bounded, sigmoidal curve: growth accelerates at first, then slows down, reaching a steady state as the animal matures.