Why does Russia have 11 time zones while China has just one? Peter Sherman investigates the history, politics and technology behind some of the world’s most incongruous ways of telling time.
Keeping time: Kruti Shrotri looks at the different timekeepers our
civilisation has used over the last five thousand years
Circadian rhythms run the biological world like clockwork. Madeleine Hurry explains how they work, from the genes in a bacterium to the human brain