Timing is everything: U.S. trio earns Nobel for work on the body’s biological clock

The presence of a biological clock was already

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surmised in the 18th century. In 1729, French astronomer Jean Jacques d'Ortous de Mairan showed that mimosa leaves, which open at dawn and close at dusk, continued this cycle even when kept in darkness. But it wasn't until the 20th century that the idea of an internal clock—as opposed one that responds to external cues like light—was settled.

The genetic basis for a daily physiological cycle was first discovered in fruit flies in the 1970s. Seymour Benzer and Ronald Konopka at the California Institute of Technology in Pasadena created mutant flies that had abnormal biological clocks. One type had a broken clock—its patterns of activity became arhythmic—whereas the others now had either a 19-hour or a 28-hour cycle. Benzer and Konopka showed the mutations all had hit the same gene, presumably in different ways. They and other researchers homed in on a gene called period.

http://www.sciencemag.org/news/2017/10/timing-everything-us-trio-earns-nobel-work-body-s-biological-clock