The history of human cultures is frequently marked by a distinctive pattern of evolution that paleobiologists term diversification and decimation. Under this process, fundamentally new socioeconomic systems appear during periods of dramatic cultural diversification,typically through cultural cladogenesis. Significant diversification episodes come about under conditions that favor group economic success under effective or geographic isolation.Typically short-lived, they are often followed by abrupt decimation under more competitive economic conditions. Regional archaeological sequences, viewed from this perspective, suggest that cultural evolutionary trends are strongly conditioned by historical contingency, though general evolutionary processes are continuously active; the emergence of new systems may be contingent on economic opportunities associated with niche reorganization; and severe competition such as that associated with demographic stress will generally favor decimation.
