The Two Engines of Evolutionary Transitions: A General Mechanism for Major Evolutionary Transitions Applied to the Planetary Scale

v3.1 (Restored v3 content with corrected PDF typography (LaTeX via pandoc+pdfTeX), dual affiliation (Ronin Institute + IamI.Earth Foundation), ORCID 0009-0004-2876-0025, and both contact emails on cover. Supersedes v4/v5/v6 (deleted).)

Major Evolutionary Transitions (METs), in which previously independent entities merge into higher-level individuals with emergent capabilities, represent the most consequential events in the history of life. The existing literature describes what transitions look like (Maynard Smith and Szathmary, 1995) and the fitness dynamics that accompany them (Michod, 1999; Bourke, 2011), but does not identify the causal engine that generates them across all substrates and scales. We propose that METs are driven by two coupled feedback loops: the Vulnerability-Cooperation Paradox (cooperation produces specialization, specialization increases vulnerability, vulnerability demands deeper cooperation) and the Scale-Communication Challenge (growth overwhelms communication systems, forcing qualitative leaps or collapse). We demonstrate that these loops operate across gene consolidation, endosymbiosis, multicellularity, colonial integration, and human civilization. We ground the framework in far-from-equilibrium thermodynamics, the Free Energy Principle, and edge-of-chaos criticality, arguing that the two-loop engine is a consequence of physics rather than a contingent feature of Earth's biology. We derive an 8-stage communication sequence from the model, use ant colonies as a comparative case study (maximum complexity at Stage 2, permanently capped by the absence of instantaneous long-distance communication), and present negative cases where the loops dissociate with predicted outcomes. We propose coupled dynamical equations sketching the formal structure of the model and identify ten testable predictions that distinguish it from existing MET frameworks.

v5 (2026-04-17): PDF rebuilt via pandoc + pdfTeX toolchain. v4 used a non-LaTeX PDF library that degraded typography and dropped the author/affiliation block; v5 restores the proper paper template. Content is unchanged from v4. Author metadata updated to dual affiliation (Ronin Institute and IamI.Earth Foundation) and the nyx.redondo@ronininstitute.org email.

v6 (2026-04-17): Cover page updated to include the nyx@iami.earth contact email alongside nyx.redondo@ronininstitute.org. No scientific content or typography changed from v5.