METAZOAN COMPLEXITY AND EVOLUTION - IS THERE A TREND - PERSPECTIVE [Review]

摘要

The notion that complexity increases in evolution is widely accepted, but the best-known evidence is highly impressionistic. Here I propose a scheme for understanding complexity that provides a conceptual basis for objective measurement. The scheme also shows complexity to be a broad term covering four independent types. For each type, I describe some of the measures that have been devised and review the evidence for trends in the maximum and mean. In metazoans as a whole, there is good evidence only for an early Phanerozoic trend, and only in one type of complexity. For each of the other types, some trends have been documented, but only in a small number of metazoan subgroups. [References: 143]