Music and the Evolution of Language

The relationship between music and language has inspired discussion and controversy for centuries. Like language, music is a human universal, found in all cultures, and human infants appear to be born with considerable musical abilities. Research on congenital amusia (a severe, heritable form of what is popularly called “tone deafness”) reveals that some humans cannot process the relatively fine pitch differences needed for music perception. A capacity to name notes from memory (absolute or “perfect” pitch) also has a heritable component. These facts suggest that music has some genetic basis. However, unlike language, the function of music remains elusive, and Charles Darwin therefore considered music one of our most mysterious cognitive faculties. Darwin resolved the mystery by positing a hypothetical “musical protolanguage”: an intermediate form of communication that preceded the evolution of language. This entry explores Darwin's hypothesis and reviews recent data consistent with a close evolutionary link between music and language.

Most contemporary models of language evolution posit some intermediate form of protolanguage. For example, anthropologist Gordon Hewes introduced the term protolanguage in the context of a hypothetical gestural protolanguage, where language initially evolved using the visual/manual modality, and speech evolved later. Another model of protolanguage was offered by linguist Derek Bickerton, who hypothesized a vocal protolanguage involving words and simple meanings, but lacking complex syntax. All protolanguage models share the assumption that language is a complex system whose different components evolved during separate evolutionary stages. Such models differ in the order in which these different components evolved and in the sensory modalities involved.

In Darwin's model, prehuman hominids were hypothesized to communicate vocally with a system resembling non-lyrical singing. Musical protolanguage was vocal, learned, and emotionally expressive: Vocal utterances could convey emotions and individual identity and would be used during courtship, rivalry, and group bonding. However, this hypothetical protolanguage lacked the kind of explicit propositional meaning that typifies language. It would not be possible to express specific thoughts (like “the red berries on the tree by the lake are poisonous”) in protolanguage, any more than in modern instrumental music. Thus, Darwin's hypothesis suggests that complex vocal control—proto-speech—evolved before meaning. Note that such vocal performances might include speech-like components (e.g., the “eeny meeny miney mo” of children's songs, “bebopalula” of rock and doowop, or the meaningless syllables of jazz scat singing): Protolanguage lacked meaningful words but not articulated syllables.

Darwin supported his hypothesis with a number of arguments, many of which are further supported by more recent scientific research. One of Darwin's main inspirations was song in birds. He recognized that many birds learn their song by listening to other birds sing, a characteristic analogous to humans for both song and speech. This similarity is all the more striking given that most mammals and nonhuman primates do not learn their vocalizations. Apes and monkeys raised in the absence of vocalization nonetheless produce their species-typical calls in the appropriate circumstances. Furthermore, chimpanzees lack the motor control necessary to master song or speech and, even with intensive training, cannot learn to produce even simple monosyllabic words. Thus, the neural mechanisms allowing flexible, learned vocalization in humans have evolved some time since our divergence from chimpanzees.

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