Limbs evolved as a means of locomotion. From the primitive rotating flagella of bacteria to the wings of flies and even our own legs, animals use these appendages to travel to find food or mates or escape predators. But in countless species across the animal kingdom, limbs are repurposed to create elaborate social displays: Birds of paradise fan out their wings and hop around in courtship dances, while crabs wave their claws to communicate to potential mating partners. As humans, we use our limbs to dance, gesture while talking, wield tools and conduct a remarkable diversity of behaviors. How does the brain control and coordinate its body parts for such distinct purposes?