"If ever there was a scientific theory that is fundamentally historical, that purports to explain change over time, it is evolution through natural selection and its corollary, humankind’s dual inheritance." writes Donald Worster. "Yet I have to admit that my fellow historians, teaching in history departments and professing to study that process of change, have been highly resistant to evolutionary theory. Why has that been generally so? Why have historians insisted on drawing a rigid boundary separating culture from nature? And what are the possibilities for overcoming this separation?"