Natural Selection Is Compression Optimization DNA as Lossy Codec, Fitness as Compression Efficiency, and the Information-Theoretic Unity of Biology An Extension of Adaptive Compression Advantage Theory (ACAT)

This paper extends the Adaptive Compression Advantage Theory (ACAT; Murata, 2026) from cognitive science to evolutionary biology by demonstrating that natural selection is a compression optimization process. DNA is a lossy codec: 3 billion base pairs encode the construction program for an organism that must function in a high-dimensional environment. Fitness, in ACAT terms, is the compression efficiency of the organism’s phenotype relative to its environmental niche—the rate-distortion performance of the genotype-to-phenotype mapping under ecological constraints. We derive that: (1) adaptation is the improvement of the genome’s compression of environmental regularities into viable phenotypes; (2) the Cambrian explosion was triggered by a sensory-input dimensionality explosion that created an arms race in compression architecture; (3) convergent evolution occurs because identical environmental compression problems have limited optimal solutions; (4) sexual selection is a compression-quality signaling system; (5) the evolution of brains was driven by the fitness advantage of real-time environmental compression over hardcoded genomic compression; and (6) the evolution of language represents a phase transition from individual to collective compression, enabling cultural evolution as a second compression system operating on the first. Each derivation generates testable predictions and connects to existing theoretical biology through the formal apparatus of rate-distortion theory. The framework provides a unified information-theoretic account of biological evolution that bridges the gap between population genetics, developmental biology, neuroscience, and cultural evolution. Keywords: evolution, natural selection, compression, rate-distortion theory, DNA, adaptation, Cambrian explosion, convergent evolution, sexual selection, brain evolution, language, cultural evolution, ACAT, information theory, fitness