Dancing animal videos Scientists study the evolution of rhythm

The sea lion studies are especially interesting. For years, scientists have thought that animals' "rhythmic entrainment" (the ability to synchronize with an external beat) was necessarily associated with vocal capacities to imitate sound. Sea lions are quite limited in the sounds they can make, which "poses a real problem for the theory that vocal mimicry is a necessary precondition for rhythmic entrainment," according to Cook.