Two Paths, One Evolution: Testing the Extended Phenotype Theory Across Legal Systems

This paper tests the extended phenotype theory of law through a comparative analysis of common law and civil law systems, arguing that apparent dichotomies (precedent vs. codification, inductive vs. deductive reasoning, judge-made vs. legislative law) reflect convergent evolution rather than fundamental differences. Both traditions evolved memetic fitness landscapes optimizing for different environmental pressures while producing functionally equivalent legal phenotypes. The analysis demonstrates that common law's precedential system and civil law's codification represent alternative reproductive strategies for legal memes: common law achieves high-fidelity transmission through citation networks and professional communities; civil law achieves it through textual canonization and academic systematization. These different strategies produced punctuated equilibrium patterns observable in constitutional moments, harmonization processes, and hybrid systems. Empirical evidence from the U.S. Uniform Commercial Code (1952-2022), European Union regulatory convergence (1957-2023), and mixed jurisdiction systems (Louisiana, Quebec, Scotland) shows legal evolution follows predictable memetic fitness functions independent of conscious design. The paper challenges legal transplant theory by demonstrating that success depends not on normative superiority but on phenotypic compatibility with existing legal ecosystems. This framework provides testable predictions for comparative law, legal harmonization, and constitutional design.