# Biosphere > **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:** Earth Systems / Evolution **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition The biosphere is the planetary system formed by living organisms and their interactions with atmosphere, oceans, land and biogeochemical cycles. ## Nexus Context Its long-running novelty, niche construction and major transitions provide the standard artificial-life systems have not yet reproduced at comparable open-ended scale. ## Evidence Boundary Calling a digital environment a biosphere is a strong claim. It should require persistent ecological closure, generativity and material-resource accounting, not merely many agents. [[wiki/Marsification|Marsification]] names a different threshold: the replacement of particular ambient biospheric services by engineered ones. A city can become dependent on manufactured water, food, thermal control and sensing without Earth ceasing to possess a biosphere. [[articles/The Last Migration Will Not Be Human|The Last Migration Will Not Be Human]] depends on this distinction and explicitly rejects literal near-term atmospheric loss. ## Relationships [[wiki/Open-Ended Evolution|Open-Ended Evolution]], [[wiki/Systems Ecology|Systems Ecology]], [[wiki/Niche Construction|Niche Construction]], [[wiki/Spaceship Earth|Spaceship Earth]], [[wiki/State-Dependent Catastrophe|State-Dependent Catastrophe]] ## Sources / Provenance - Earth-system science and evolutionary biology.