Populations fluctuate but seem generally stable in the long run. Species evolve slowly, or even seem to be more or less in “stasis” for much of their existence. Multispecies communities are recognizable over hundreds of thousands or even millions of years.
The hypothesis is that much of the structure and stability seen at the macro level, in both evolution and ecology, is the result of an ongoing process of selective elimination of unstable or marginal configurations.
Much of biological thinking starts with the view that, given enough time, anything can evolve. The authors think that it is more fruitful to delineate first the forbidden states of ecology and evolution — “forbidden” not because they cannot occur, but because they cannot last.
Selective elimination processes are powerful evolutionary forces, and they are not specific to biological systems. The evolution of the planetary system or, for example, of the rings of Saturn has been driven by the elimination of many physical bodies. It is hypothesized that elimination processes in biology are different only in that the forces of evolution continually generate biological systems that approach or transgress eliminative boundaries, and thus elimination is a never-ending process.