the theory that language is a development of natural interjections (cf. bow-wow, int. n.2b).

attributive./ˈbaʊwaʊ/, as in bow-wow theory, applied in ridicule to the theory that human speech originated in the imitiation of animal sounds.

Psychology and Linguistics. Originally: the theory that in the development of language an inherent connection exists in the mind between sound and…

the theory that language originated in an attempt to imitate the body's gestures with the vocal organs.

the theory (propounded by Jespersen) that language evolved from primitive singing.