Darwin states that it is not speech, but humans’ “large power of connecting definite sounds with definite ideas” that is definition of language. Tecumseh Fitch writes a Language Log guest post on Darwin’s theories of language evolution. I had never known that Darwin’s theories did not restrict themselves to the evolution of the species. Fitsch discusses chapter two of the Descent of Man, in which Darwin considers the evolution of the human mind.

Darwin lays out his theory of the stages of evolution where an increase in intelligence is followed by the complex vocal control required for singing. In the third stage, meaning is added to song, “which was both driven by, and in turn fueled, further increases in intelligence.”

Darwin recognized that physiology is not sufficient for learning songs: “crows have a syrinx as complex as a nightingale’s but use it only in unmusical croaking.”

…birds have fully instinctive calls, and an instinct to sing. But the songs themselves are learned. He recognized the parallel between infant babbling and songbird “subsong”, and recognized the key fact that cultural transmission ensures the formation of regional dialects in both birdsong and speech.

Darwin describes the next step, which Fitch calls a “musical protolanguage” (Fitch, 2006), which would improve by sexual selection and be used in courtship, to establish territory, and to express emotions. While Fitsch also highlights that gesture plays an important role in conveying meaning, both in Darwin’s writings and other sources, I found the theories relating to song most intriguing.

I have no basis of research to speak from, but this theory resonates with my own experience. It seems logical to me that language would stem from song, where a complex serious of sounds and tones yielded complex meaning and only later would the simpler words evolve. In seeing how my own child learned language, he seemed to leap forward with whole phrases. While his first stabs at communication seemed to be the identification of simple nouns, most language echoed sounds strung together in a rhythm rather than, apparently, putting those simple nouns into a more complex grammar.

My personal experience seem to jive with theories of Otto Jespersen’s hypothesis of a “holistic protolanguage.” More recently championed by linguist Alison Wray (Wray, 1998, 2000) and neuroscientist Michael Arbib (Arbib, 2005) with supporting evidence from modern studies of adult language, child language acquisition, and cognitive neuroscience.

Fitch notes that the key remaining question is “how emotionally-expressive musical proto-language made the transition to true meaningful language.” I would think that if just one individual were to evolve (or learn?) to connect more abstract meaning to phrases then he or she would teach their offspring, which would provide all sorts of fitness benefits. Perhaps that is the essential question: how much of the change was due to physiological changes rather than learned ones, and why it happened in humans and not in nightingales.

Fitch also contrasts Darwin’s assertion that the evolution of language was driven by courtship with the more modern view of music and song in the context of childcare.

The popular notion that music evolved for courtship (Miller, 2000, 2001) stands on a surprisingly weak empirical footing compared to a less obvious, but better-documented function of music: mother-infant communication (Trainor, 1996; Trehub, 2003a, 2003b). Mothers sing to their infants all over the world, even those who claim to be unable to sing (Street, Young, Tafuri, & Ilari, 2003), and infants both prefer song to speech, and respond to song in manifestly adaptive ways (e.g. engaging with and getting excited by play songs, and being lulled to sleep by lullabies (Trehub & Trainor, 1998).

In the final stage, Darwin theorizes that language interacts with the evolution of intelligence and cognitive thought:

…language would have “reacted on the mind by enabling and encouraging it to carry on long trains of thought” which “can no more be carried on without the aid of words, whether spoken or silent, than a long calculation without the use of figures or algebra”. Thus began the interactive evolutionary spiral that led to modern humans.