Nitrogen Deficiency as Root Pathology of Earth Biology

The search for extraterrestrial life assumes Earth biology is the standard. This paper proposes the opposite: Earth biology is a pathological variant produced by a specific planetary nitrogen accident. When abiotic nitrogen supplies declined in early Earth history, biological nitrogen fixation emerged as an emergency adaptation — not an evolutionary improvement. Every subsequent feature of Earth life, including predation, sexual reproduction, scarcity-driven evolution, and intelligence as a weapons system, is proposed as a downstream consequence of this single planetary failure. A counterfactual standard biological life — one on a nitrogen-complete planet — would lack all five of these features and would be unrecognisable to Earth-biology-trained observers. This reframe has direct implications for biosignature design, SETI methodology, and the interpretation of apparent sterility in planetary surveys.