It’s very hard to come up with a good definition of music. Some cultures make music by banging on drums, blocks, or pieces of metal, emphasizing rhythm over melody. In others, the main instrument is the human voice; in others, music is inseparable from dance. In some cultures, music is reserved for special occasions; in others, people create a more or less continual musical soundtrack to their lives. Some cultures analyze music in obsessive detail; others are puzzled by any need to discuss it.
Music in human society is certainly very ancient. The oldest known instrument, a flute carved from the bone of a bird, is around 40,000 years old. Why should our ancestors have wanted or needed music as they struggled to survive an ice age? Charles Darwin believed that music evolved as a vehicle for sexual selection, a form of exhibitionist display or prowess like the mating “songs” and “dances” of animals. But there are plenty of other ideas. Perhaps music acted as a ritualistic device for social bonding and cohesion, for establishing group identity? Maybe it stems from the universal musicality of mother-infant communication? Perhaps music and language were once blended in a single form of vocalization. Maybe there is not a single origin or cause of music, but many. We just don’t know, and perhaps we never will.