The evolutionary story of circadian rhythms is under scrutiny
The Earth has rhythm. Every 24 hours, the planet pirouettes on its axis, bathing its surface alternately in sunlight and darkness.
Organisms from algae to people have evolved to keep time with the planet’s light/dark beat. They do so using the world’s most important timekeepers: daily, or circadian, clocks that allow organisms to schedule their days so as not to be caught off guard by sunrise and sunset.