The evolution of Darwin’s finches is one of science’s most compelling examples of how natural selection can drive changes in anatomy. The incapability of species that can crack hard seeds to generate the fast movements of the beak required for quick handling of small seeds and for singing complex songs has a major influence on interspecies’ mating dynamics, probabilities of hybridisation, and ultimately the process of speciation by divergence in these songbirds. But why can some species produce extremely fast open-close sequences of the beak while other species cannot? The mechanical principles behind this vastly important phenomenon are currently unknown. By integrating biomechanical and morphological analyses using state-of-the-art techniques, both in laboratory and field settings, this project will finally unveil this underlying causation, and hence significantly advance our understanding of the important evolutionary model system of Darwin’s finches.