# Virus > **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 / Replication / Boundary Cases **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition A virus is a genetic replicator that depends on host-cell machinery for reproduction and occupies a boundary in debates about life. ## Nexus Context Viruses show that dependence does not negate evolutionary agency at the lineage level. Their host manipulation supplies an analogy for low-complexity replicators affecting more complex systems. ## Evidence Boundary Biological viruses and computer viruses share replication vocabulary but differ materially. Neither dependence nor evolution alone establishes sentience. ## Relationships [[wiki/Replicator|Replicator]], [[wiki/Host-Parasite Coevolution|Host-Parasite Coevolution]], [[wiki/Computer Worm|Computer Worm]], [[wiki/Sentience|Sentience]] ## Sources / Provenance - Virology and evolutionary-biology texts; PNAS evolvable-AI paper.