Tuesday, April 24, 2007
4:15 pm
B17 Upson Hall

Computer Science
Spring 2007

Geoffrey West
Santa Fe Institute

The Complexity, Simplicity, and Unity of Living Systems; Universal
Scaling Laws from Cells to Cities

Life is the most complex phenomenon in the Universe manifesting an extraordinary diversity of form and function over an enormous scale. Yet, many of its most fundamental and complex phenomena scale with size in a surprisingly simple fashion. For example, metabolic rate scales as the 3/4-power of mass over 27 orders of magnitude from molecular levels up to the largest multicellular organisms. Similarly, time-scales, such as lifespans and growth-rates, increase with exponents which are typically simple powers of 1/4. It will be shown how these quarter power scaling laws follow from fundamental universal principles embedded in the dynamical and geometrical structure of underlying networks. These lead to a general quantitative, predictive theory that captures essential features of many diverse biological systems. Examples will include animal and plant vascular systems, growth, cancer, aging, sleep and mortality. These ideas will be extended to discuss social organizations such as cities: to what extent are they an extension of biology? Analogues to metabolic rate and behavioral times in cities scale counter to their behavior in biological systems: the pace of life in cities increases with size. Driven by innovation and the creation of wealth this has dramatic implications for their growth, development and sustainability which, left unchecked, potentially sow the seeds for their collapse.