# Nucleic Acid > **Machine-Evolution Nexus:** [[articles/Digital Darwinism and the Invisible World of Machine Evolution|Digital Darwinism and the Invisible World of Machine Evolution]] places this concept within the history and governance of substrate-independent evolution. **Domain:** Molecular Biology / Heredity **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition Nucleic acids are polymers, principally DNA and RNA, that store, transmit and help express biological hereditary information. ## Machine-Evolution Context They are one physical implementation of inheritance, not the definition of heredity itself. Digital evolution demonstrates that Darwinian dynamics can use other media when equivalent causal functions are present. ## Continuity and Evidence Boundary Substrate independence is functional, not magical: DNA and RNA operate only through chemical machinery, energy flows and cellular context, just as digital descriptions require interpreters. ## Relationships [[wiki/DNA|DNA]], [[wiki/RNA|RNA]], [[wiki/Genetic Code|Genetic Code]], [[wiki/Substrate-Independent Evolution|Substrate-Independent Evolution]] ## Sources / Provenance - Alberts et al., _Molecular Biology of the Cell_.