They may not yet be kings of the swingers, but macaque monkeys can keep time to music and move to the beat. Well, at least two adult macaques can, who were trained by researchers to tap along to different kinds of music. Their work challenges the so-called vocal-learning hypothesis, which holds that only species with complex vocal learning, like humans and songbirds, can spontaneously move to the groove. Macaques are not vocal learners.