The Thermodynamic Considerations of Biological Evolution; the Role of Entropy

Although Darwin's theory of biological evolution is the cornerstone of modern biology, it lacks proper physical foundations. We consider ecosystems as closed systems that only exchange energy and information, not matter with the outside. Moreover, predictable and periodic fluctuations in entropy, genetic diversity, population number, and resource availability form a cyclic process that can be analyzed via thermodynamic principles. The sun's energy input drives a reversed Carnot cycle in four phases. The first phase is low entropy, a fast-changing environment spurring genotype-phenotype plasticity. In phase 2, the growing population increases entropy, forming nutrient cycles via symbiotic, parasitic, and predator-prey relationships. In phase 3, competitive and chaotic interactions spread genetic innovations in the overpopulated, stressed ecosystem. Finally, in phase 4, extinction purges the non-evolvable genomes, but the surviving species carry the cycle's genetic innovations on which further evolutionary progression is possible. The sun's energy input is a potent driver of genetic complexity through the cyclic compression and expansion of the ecospace. Using thermodynamic principles, we show that ecosystems conserve genetic complexity. Therefore, intellectual complexity never decreases but increases or remains constant might be a new law of physics, the second law of intellect.