Evolution as a self-organized critical phenomenon.

TLDR

The environment of a species is shaped by other evolving species, making it non‑constant over time. The study presents a simple mathematical model of biological macroevolution. The model describes an ecology of adapting, interacting species and its results are compared with fossil‑record data. The ecology evolves to a self‑organized critical state with periods of stasis and avalanches, explaining punctuated equilibrium; single species exhibit intermittent evolution, large bursts need no external cause, and extinctions of all sizes—including mass extinctions—arise from ecosystem dynamics.

Abstract

We present a simple mathematical model of biological macroevolution. The model describes an ecology of adapting, interacting species. The environment of any given species is affected by other evolving species; hence, it is not constant in time. The ecology as a whole evolves to a "self-organized critical" state where periods of stasis alternate with avalanches of causally connected evolutionary changes. This characteristic behavior of natural history, known as "punctuated equilibrium," thus finds a theoretical explanation as a self-organized critical phenomenon. The evolutionary behavior of single species is intermittent. Also, large bursts of apparently simultaneous evolutionary activity require no external cause. Extinctions of all sizes, including mass extinctions, may be a simple consequence of ecosystem dynamics. Our results are compared with data from the fossil record.