A new look at universals and specificities in the songs of humpback whales.

In this issue’s featured article, Mercado and Perazio (2021) describe songs of humpback whales using acoustic qualities, in part to determine the degree of similarity in songs across time and space that have not been revealed by information-theoretic analyses. They are particularly interested in evaluating alternative explanations of song variations in humpback whales. They argue that if humpback whales’ songs “are . . . transmitted through acoustic contact followed by imitation” (p. 29) then (a) songs of populations not in acoustic contact should diverge, (b) songs of the same population should diverge increasingly over time, and (c) song forms separated by multiple decades either within or across populations should be dissimilar. Alternatively, acoustic similarities in song structure across populations and/or across decades in the same population would challenge the hypothesis that socially mediated learning is the primary driver of variation in the structure of humpback whales’ songs over time. If that is the case, then identifying universal properties of song composition is important to move the field forward. Broadening the analytical tool kit can help in this effort.