In 1729 the French astronomer Jean de Mairan reported that the movement of leaves of Mimosa continued when the plant was isolated in continuous darkness - proving that the daily cycle was not driven by light and darkness, but was instead under the control of a biological clock. It was not until the 1950s that "circadian" (circa- approximately, dies- a day) was coined to describe these autonomous rhythms and the clocks that drive them. This video recreates the circadian leaf movements first seen almost 300 years ago. Back to the video index page |