The 2017 Nobel Prize in Physiology or Medicine was awarded to Jeffrey C.Hall, Michael Rosbash and Michael W. Young for their discoveries of molecular mechanisms controlling circadian rhythms. There are a number of exciting stories and a long list of scientists that contributed to these findings. In this review we review the history of the exploration of biological clocks and the studies of genetic and molecular mechanisms of circadian rhythms. The scientific significance and prospective applications of biological complexity including the emergence of biological clocks are discussed. We also discuss the paradigms of complex systems and the necessity of introducing scientific analysis into traditional Chinese medicine.