Temporal organization and disorganization in organisms.

The study of biological rhythms has always been a highly interdisciplinary field of research, one that is constantly breaking new ground. Developments during the past 10 years are transforming our ideas about the dynamics of physiological regulation in two ways: (i) homeostasis is really homeodynamics, with sophisticated but robust patterns of hierarchically nested rhythms covering several orders of magnitude in the frequency domain; (ii) there is much more irregularity than previously believed in processes as basic as the heart rate, suggesting either a chaotic generator, a complex pattern of interacting systems with different frequencies, or possibly both. This behavior is consistent with that expected of organisms as complex adaptive systems.