These two papers present contrasting views of music's relationship to evolutionary theory, drawing on a wide range of diverse sources. Savage et al. suggest that music is a mechanism for enhancing social bonds, its role in evolution being bound to its efficacy in establishing group cohesion. Mehr et al. reject this idea, claiming that music had dual adaptive functions in human evolution concerned with (i) coalition signalling, and (ii) signalling parental attention as a substitute for parental proximity. Both papers represent significant contributions to the literature on music and evolutionary theory, although both suffer from similar problems in the ways in which they operationalize conceptions of music that in one case weaken the force of the argument and in the other critically undermine the conclusions reached.

Both papers make frequent reference to the ethnomusicological literature and to findings with respect to cross-cultural musical universals. However, in outlining and defending their theses both tend to rely on ideas of music that reflect Western conceptions, substantially in Mehr et al., much less so in Savage et al. For Savage et al., this is most evident in their treatment of music in development, where they suggest that singing to infants allows “parents to communicate specific emotional messages to infants”; what's missing here is any sense of the interactive and reciprocal nature of musical engagement in infancy and, indeed, adulthood (see Malloch & Trevarthen, Reference Malloch and Trevarthen2009). This is unfortunate, as in building a case for a close relationship between music and social bonding their paper otherwise engages fruitfully with the distinction between music as an interactive and as a presentational medium (after Turino, Reference Turino2008) although their characterization of that distinction is too categorical and could have benefited from reference to studies by Slobin (Reference Slobin1992) and Finnegan (Reference Finnegan1989).

In the case of Mehr et al., the conception of music that is at the heart of the paper – “Music is an auditory display built from melodies and rhythms” – is critically flawed by its curious neglect of the literature on music as a participatory and interactive medium. Although one of their two hypotheses concerns a signalling function of music in group behaviour, the members of the “group” that engages in musical signalling seem more like fireflies in their undifferentiatedly synchronous signalling than like the “Aka Congo Basin hunter-gatherers” to whom the authors refer, whose group musical behaviour is far away from synchrony in its spontaneously supple polyphony. The processes through which the members of a group interact with each other in creating and sustaining a “musical signal” are here treated almost as occurring in a black box, whereas the primary argument with respect to their musical signalling hypothesis really requires that the dynamics of those processes be understood and explained (see, e.g., Gratier, Reference Gratier2008; Keller, Novembre, & Hove, Reference Keller, Novembre and Hove2014; Turino, Reference Turino2008).

Another curious omission from both papers is any consideration of the concept of attachment, mentioned in passing by Savage et al. and absent from Mehr et al. A substantial literature supports the idea that attachment constitutes a process grounded in mammalian neurophysiology that is powerfully and flexibly present in humans across the lifespan, extending to a wide variety of social relationships (see, e.g., Coan, Reference Coan, Cassidy and Shaver2008; Feldman, Reference Feldman2017). Reference to that literature could have strengthened the argument in Savage et al. although problematizing that presented in Mehr et al. A reorientation of the arguments towards attachment rather than bonding, a focus on infant–parent attachment, an acknowledgement that music plays a significant role in reinforcing this as an interactive medium, and an extension of the neural and behavioural correlates of parent–infant attachment behaviours to interactions with adults, kin, and strangers can yield what, according to Mehr et al., appears unviable; the instauration in the human behavioural repertoire of a mechanism – which we can call “something-like-music” – that can facilitate dyadic and group bonding.

Finally, both papers appear to conceive of music as a discrete domain of human experience, having parallels with but being distinct from language. Savage et al. suggest that because “music and language are both found universally in all known societies,” they independently fulfil adaptive functions, whereas Mehr et al. assert that “language adequately provides whatever social functions grooming may have. As a social coordination or bonding mechanism, music thus appears to have no advantages over language and many disadvantages” (sect. 3.2.3, para 5). Ethnomusicological and ethnolinguistic evidence, together with a growing number of studies of real-time communicative interaction (e.g., Gorisch, Wells, & Brown, Reference Gorisch, Wells and Brown2012; Robledo Del Canto, Hawkins, Cross, & Ogden, Reference Robledo Del Canto, Hawkins, Cross and Ogden2016) would suggest that a boundary between music and language is not clear-cut and that it may, in fact, not exist.

A fascinating recent instance is study by Senft (Reference Senft, Capone, Carapezza and Lo Piparo2018), who finds that the preferred mode of communicative interaction among the Trobriand islanders is biga sopa, “joking or lying speech … speech which is not vouched for,” which is “characterised by four genres; sopa (joke, lie, trick), kukwanebu sopa (story), kasilam (gossip) and wosi (songs).” Here, speech in a register that is recognizable as phatic (after Malinowski, Reference Malinowski, Ogden and Richards1923) shades into music in the form of song; its function is strategic and social. As Senft notes (Reference Senft, Capone, Carapezza and Lo Piparo2018, pp. 211–212), “the biga sopa variety channels emotions, it keeps aggression under control, and it keeps possibilities of contact open … this concept with its tension-releasing functions secures harmony in Trobriand society.”

The biga sopa speech register fulfils a function that I and others (Cross, Reference Cross2006, Reference Cross2014; McLeod, Reference McLeod1974) have proposed as integral to music across cultures and times: the management of situations of social uncertainty. Thinking of music as overlapping significantly – as an interactive medium – with speech registers oriented towards establishing and sustaining social relationships, the function of “something-like-music” in social bonding appears to fall out of its potential for managing situations of social uncertainty from dyads to groups, and from situations ranging across caregiver–infant interaction (Malloch & Trevarthen, Reference Malloch and Trevarthen2009), the Aka's performance of mokondi massana to delight the forest (Lewis, Reference Lewis, Botha and Knight2009), and the sophisticatedly crude chanting of football crowds (Kytö, Reference Kytö2011).

And, of course, in whatever form something-like-music manifests itself, we do it together because it's fun!