I was trained as a geneticist, to recognise questions on two scales: how do genomes, in cells, build organisms? And how do organisms, in evolving populations, select their genomes? The biological clock is a fascinating example, as its 24-hour rhythms adjust the daily lives of plants (and humans). Understanding how the clockwork helps to build an Arabidopsis plant has linked our plant systems biology to crop science and evolutionary adaptation. Life scientists might answer both questions together, in nature, if that example is general. As mid-century approaches, should we?