# Symbiosis > **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:** Evolution / Ecology **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition Symbiosis is sustained close interaction between different organisms or lineages and may be mutually beneficial, harmful or context-dependent. ## Nexus Context Major-transition theory treats some durable symbioses as routes toward higher-level organization. Digital systems can model reciprocal dependence and conflict control. ## Evidence Boundary Symbiosis is not automatically harmony or equality. Dependency can create domination, lock-in and custodial power. ## Relationships [[wiki/Coevolution|Coevolution]], [[wiki/Cooperation|Cooperation]], [[wiki/Major Evolutionary Transitions|Major Evolutionary Transitions]], [[wiki/Human-Machine Symbiosis|Human-Machine Symbiosis]] ## Sources / Provenance - Lynn Margulis; evolutionary-transition literature.