Illustration of the US geneticist Michael Young (born 1949). Young has spent his career studying circadian rhythms in fruit flies (Drosophila melanogaster). Robash isolated and sequenced the period gene, a rhythm-regulating gene, whose product accumulates during the night and degraded during the day. He went on to discover other rhythm-regulating genes, that were expressed throughout the body, and that responded to different stimuli, such as light. The same self-regulating biological clock has been shown to exist in other animals, including humans. Young, along with Jeffrey C Hall and Michael Rosbash (who together independently discovered the period gene), was awarded the 2017 Nobel Prize in Physiology or Medicine for their discoveries of molecular mechanisms controlling the circadian rhythm.