Musical activity is universal among the human species, and musical instruments over 35,000 years old have been found suggesting that the human preoccupation with music has been an enduring one. But why do humans continually and universally practice music? Darwin also puzzled over this, remarking that, "As neither the enjoyment nor the capacity of producing musical notes are faculties of the least direct use to man in reference to his ordinary life, they must be ranked amongst the most mysterious with which he is endowed" (1871, p. 355). Here I take up Darwin's concern for music and offer a new theory of its origins. My interdisciplinary approach aims to harmonize biological and cultural considerations by discussing how music functions for both intrapersonal and interpersonal synchronization.