The defining feature of biological systems is that they were created not by design or by accident, but by a process of mutation and selection. For many biological systems, we know much more about the molecular details of the components than we do about the evolutionary pressures than produced them. Though it seems intuitively clear that biological clocks should in some sense be matched to the rhythms in the external environment, the quantitative relationship between clock properties and fitness is largely unknown. For example, the period of oscillation in biological clocks is typically biased away from being exactly 24 hours (hence the term circadian = 'about daily'). For humans, the clock tends to be slower than 24 hours.

Using the power of bacterial model systems, we are working to quantify the relationship between the properties of rhythms and the ability of cells to grow and divide in fluctuating environments. We are also working to understand the historical evolutionary trajectory of circadian clocks. We are particularly interested in what the evolutionary precursors of self-sustaining rhythms were, and what led to the emergence of the first biological clocks.