Since its inception the science of physiology, like many other non-physical disciplines, has been guided in its development by the mechanical models of physics. That strategy has proven to be extraordinarily successful, even surviving the introduction of fractals into the modeling strategy. That is until quite recently. The true complexity of physiologic networks has been revealed with the development and implementation of ever more sensitive sensors and mathematically sophisticated data processing techniques. These developments have led to a divergence of the modeling strategies appropriate for the physical sciences from those for the life sciences. Therefore, we review how far the fractal concept has taken us into the non-mechanical interpretation of physiology. What emerges in this brief review of fractal physiology is the increasing importance of criticality, the cooperative nature of networks in physiologic behavior, and the importance of the fractional calculus in characterizing the dynamics of living systems. We draw some further inferences from the review and speculate as to what research directions might be most productive for continuing future success.