Spatiotemporal Organization in Biological and Chemical Systems: Historical Review

Abstract

The ability to tell time and location is characteristic of living organisms. We are all aware of our daily cycle of sleep and wakefulness, connected to underlying circadian rhythms of body temperature and hormone levels. Equally familiar to us are the relentless beating of our heart and the slower rhythm of breathing. Proper function of many of our organs depends not only on temporal periodicity but also on spatially organized behavior. For example, during one heart beat, a wave of muscular contraction must pass over the surface of the ventricle at the proper speed and in the right direction so as to pump blood efficiently through the aorta. Similarly, proper digestion relies on the correct tempo and direction of peristaltic waves in the intestine. Surely the most dramatic example of clocks and maps in biological systems is provided by the developing embryo, as the bau-plan of a complicated multicellular organism unfolds in a spectacular display of cellular differentiation and morphogenetic movements strictly coordinated in space and time. To account for the essential, intrinsic spatiotemporal organization of biological organisms in terms of the basic principles of biophysical chemistry, a new approach to biology is necessary.