Using synthetic biology to study gene regulatory evolution

•Despite decades of research, a quantitative understanding of enhancer function has eluded discovery.•Libraries of designed regulatory elements can be used to explore enhancer structure and effects on activity.•The study of synthetic regulatory elements allows the examination of mutations found in natural populations, including those that are rare and deleterious.•Synthetic networks will provide direct and tractable tests of how gene regulatory networks function, providing new material for the study of variation.