The chemotaxis pathway of bacteria is a signalling system that, by controlling flagellae, allows the bacterium to respond to chemical stimuli such as food or poison. Are the protein components and kinetics of biochemical pathways such as this fine-tuned to achieve the desired response? From new computer simulations, it seems not. Rather the system exhibits ‘robustness’, meaning that even gross perturbations of many parameters do not prevent its operation. The concept opens up several research horizons, and might usefully be employed in studying the tolerance of outbred populations to genetic polymorphisms.
