At the same time, by making revisionary change a necessary condition of revolutionary science, Kuhn ignores important discoveries and developments that are widely regarded as revolutionary, such as the discovery of the structure of DNA and the revolution in molecular biology. Kuhn’s view is that discoveries and revolutions come about only as a consequence of the appearance of anomalies. Yet it is also clear that a discovery might come about in the course of normal science and initiate a ‘revolution’ (in a non-Kuhnian sense) in a field because of the unexpected insight it provides and the way it opens up opportunities for new avenues of research.  The double-helical structure of DNA was not expected but immediately suggested a mechanism for the duplication of genetic information (e.g. in mitosis), which had enormous consequences for subsequent biological research.