# Biological Organization > **Machine-Evolution Nexus:** [[articles/Digital Darwinism and the Invisible World of Machine Evolution|Digital Darwinism and the Invisible World of Machine Evolution]] places this node within the history and governance of substrate-independent evolution. **Domain:** Biology / Systems **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition Biological organization is the nested arrangement of molecules, cells, organisms, groups and ecosystems into interacting functional levels. ## Nexus Context Major evolutionary transitions occur when previously independent units form a new higher-level individual with coordinated reproduction and conflict control. ## Evidence Boundary Hierarchy alone does not prove a new evolutionary individual. The level at which heredity and selection operate must be demonstrated. ## Relationships [[wiki/Major Evolutionary Transitions|Major Evolutionary Transitions]], [[wiki/Unit of Selection|Unit of Selection]], [[wiki/Scalar Nesting|Scalar Nesting]], [[wiki/Distributed Intelligence|Distributed Intelligence]] ## Sources / Provenance - Maynard Smith and Szathmáry (1995); multilevel-selection literature.