What is the use of the comparative approach in studying the origins of language and music?

Diagrammatic representation of the comparative
approach (as discussed in ten Cate & Honing, 2022)

Comparative studies can be done in several ways. One approach is to examine the sounds made by animals and look for shared features or parallels with language or music. To study these, one can, for example, examine how the structure of a sequence of sounds compares to syntactic structures in language or rhythmic structures in music, or whether harmonic sounds are recognized by their pitch (like in music) or by their spectral structure (like in speech). The presence of such features can indicate that similar sensory or cognitive mechanisms may underlie their perception and production and those needed for language and music in humans. However, one needs to be cautious with drawing such conclusions. That a sound produced by an animal has certain features in common with language or music may be incidental and a result of human interpretation, rather than indicating shared mechanisms per se. Animal sounds showing, for example, a specific rhythmic pattern (e.g., in the call of the indri, a lemur species; De Gregorio et al., 2021) or that contain tones based on a harmonic series (e.g., in the hermit thrush; Doolittle et al., 2014), need not indicate an ability of the animal to perceive or produce rhythms or harmonic sounds in general, as is common in humans. To show this, it is necessary to demonstrate the perception or production of such patterns outside and beyond what is realized in the species-specific sound patterns. This requires a second approach: using controlled experiments to address whether animals can (learn to) distinguish and generalize artificially constructed sounds that differ in specific linguistic or musical features. The two approaches, observational-analytical and experimental, are complementary: the first one may hint at presence of a certain ability, while the second one can test its existence and the limits of the capacity (Adapted from: ten Cate & Honing).

De Gregorio, C., Valente, D., Raimondi, T., Torti, V., Miaretsoa, L., Friard, O., Giacoma, C., Ravignani, A. & Gamba, M. (2021). Categorical rhythms in a singing primate. Current Biology, 31(20), R1379–R1380. https://doi.org/10.1016/j.cub.2021.09.032 

Doolittle, E. L., Gingras, B., Endres, D. M. & Fitch, W. T. (2014). Overtone-based pitch selection in hermit thrush song: Unexpected convergence with scale construction in human music. Proceedings of the National Academy of Sciences, 11(46), 1–6. https://doi.org/10.1073/pnas.1406023111

Ten Cate, C. & & Honing, H. (2023, in press). Precursors of Music and Language in Animals. Sammler, D. (ed.) Oxford Handbook of Language and Music Oxford: Oxford University Press. Preprint: psyarxiv.com/4zxtr.