The origin of biological clocks
The evolutionary story of circadian rhythms is under scrutiny
LIFE'S CYCLES Throughout the human body, circadian clocks keep activities running on a daily schedule of day and night. New work is shedding light on the origin and evolution of biological clocks.
Todd Churin
The Earth has rhythm. Every 24 hours, the planet pirouettes on its axis, bathing its surface alternately in sunlight and darkness.