Dr. Provine is investigating the origins, development, and influence of the neutral theory of molecular evolution in relation to modern evolutionary biology. The neutral theory states that the vast majority of changes at the molecular level in natural populations are caused by random fixation, through random sampling drift, of selectively neutral or nearly neutral mutations. This is a strikingly new theory unrelated to earlier theories of selectively neutral evolution except in certain formal aspects, and has stimulated more than two decades of intense controversy among evolutionary biologists. Dr. Provine is using the selectionist/neurtralist debate as a window through which to view the complex interactions of the new molecular biology with evolutionary biology of the 1970s and 1980s. He is examining this debate through an historical and cultural perspective.