1. Although the analogy of industral systems to natural ecosystems is not perfect, the two systems do share some fundamental features.

·     They are both composed of individual interacting units, each of which is driven to increase its size or number.

·     The actors in both cases depend upon supplies of resources—in particular, energy, materials, and means of removing or decontaminating by-products.

·     The interactions of the individual actors result in complex patterns of energy and materials flows.

They also have important differences.

·     Materials cycles are essentially closed in mature natural systems but not in industrial systems.

·     The total productivity of mature natural systems is essentially constant, whereas the productivity of industrial systems tends to grow exponentially.

·     Mature natural systems are more or less sustainable, whereas industrial systems appear nonsustainable as currently configured, either because of production and consumpion patterns or because of their impacts on the environment.

·     The pace of change in mature natural systems is relatively slow—on an evolutionary time scale—but the technology of industrial systems changes rapidly; these changes affect the systems themselves as well as the relationship between industry and the environment.

·     Interactions in industrial systems are often mediated by long-range transport, whereas interactions in natural systems generally occur between organisms in proximity to each other.

·     The decomposers of natural systems are small and ubiquitous, whereas the decomposers (e.g., recyclers and waste disposers) of industrial systems are relatively few and far between.

·     The information content, flows, and feedback loops (e.g., DNA and self-regulation through chemical signals) in natural systems are much more complex and richer than those of industrial or manmade systems.