Biological Complexity and Cognitive Evolution
Biological Theory March 30, 2026 Peter Jedlicka, Jaroslav Varchola, Jakub Betinsky
Biological evolution appears to increase complexity, but defining complexity is difficult. Measures that assign low complexity to both highly ordered and highly random systems and high complexity to intermediate systems show that most biological systems fall in this range. These measures quantify the information an organism stores about its environment, supporting the idea that evolution increases the knowledge organisms accumulate about their niche. This aligns with cognitive biology, which views evolution as a progressive accumulation of knowledge or epistemic complexity, resembling a cognitive ratchet pushing toward higher complexity. A dynamic environment creates problems to be solved, and each solution becomes embodied knowledge. The framework also links to integrated information theory, suggesting that human self-reflection marks a new qualitative level in epistemic complexity.