Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2000.Includes bibliographical references (p. 219-245).A new microevolutionary theory of complex design within language is proposed. Experiments were carried out that support the theory that complex functional design - adaptive complexity - accumulates due to the evolutionary algorithm at the simplest levels within human natural language. A large software system was developed which identifies and tracks evolutionary dynamics within text discourse. With this system hundreds of examples of activity suggesting evolutionary significance were distilled from a text collection of many millions of words. Research contributions include: (1) An active replicator model of microevolutionary dynamics within natural language, (2) methods to distill active replicators offering evidence of evolutionary processes in action and at multiple linguistic levels (lexical, lexical co-occurrence, lexico-syntactic, and syntactic), (3) a demonstration that language evolution and organic evolution are both examples of a single over-arching evolutionary algorithm, (4) a set of tools to comparatively study language over time, and (5) methods to materially improve text retrieval.by Michael Lloyd Best.Ph.D
