Savage et al. include groove and dance among musical features which enhance social bonds and group coherence. I discuss groove as grounded in structure and performance, and relate musical performance to play in nonhuman animals and humans. The interplay of individuals' contributions with group action is proposed as the common link between music and play as contributors to social bonding.

We propose that not social bonding, but rather a different mechanism underlies the development of musicality: being unable to survive alone. The evolutionary constraint of being dependent on other humans for survival provides the ultimate driving force for acquiring human faculties such as sociality and musicality, through mechanisms of learning and neural plasticity. This evolutionary mechanism maximizes adaptation to a dynamic environment.

The music and social bonding (MSB) hypothesis suggests that damage to brain regions in the proposed neurobiological model, including the ventromedial prefrontal cortex (vmPFC), would disrupt the social and emotional effects of music. This commentary evaluates prior research in persons with vmPFC damage in light of the predictions put forth by the MSB hypothesis.

Both the music and social bonding (MSB) hypothesis and the music as a credible signal hypothesis emerge as solid views of how human music and human musicality might have evolved. Nonetheless, both views could be improved (and tested in better ways) with the consideration of the way in which human language(s) might have evolved under the effects of our self-domestication.

Savage et al. do an excellent job of making the case for social bonding in general, but do a less good job of distinguishing the manners by which dance and music achieve this. It is important to see dance and music as two parallel and interactive mechanisms that employ the “group body” and “group voice,” respectively, in engendering social cohesion.

Both papers – to different degrees – underplay the interactive dimensions of music, and both would have benefited from integrating the concept of attachment into their treatments of social bonding. I further suggest that their treatment of music as a discrete domain of human experience and behaviour weakens their arguments concerning its functions in human evolution.

The music and social bonding (MSB) hypothesis proposes that human musicality has evolved as mechanisms supporting social bonding. We consider the MSB hypothesis under the lens of amnesia by arguing how patients with amnesia, especially those with Alzheimer's disease, can benefit from music, not only to retrieve personal memories, but also to use them for social bonding.

Human infants are born ready to respond to affiliative signals of a caretaker's face, body, and voice. This ritualized behavior in ancestral mothers and infants was an adaptation that gave rise to music and dance as exaptations for promoting group ritual and other social bonding behaviors, arguing for an evolutionary relationship between mother and infant bonding and both music and dance.

Is musicality an individual level adaptation? The authors of this target article reject the need for group selection within their model, yet their arguments do not fulfill the conceptual requirements for justifying such a rejection. Further analysis can highlight the explanatory value of embracing multilevel selection theory as a foundational element of the music and social bonding (MSB) hypothesis.

“Music As a Coevolved System for Social Bonding” (MSB) is a brilliant synthesis and appealing hypothesis offering insights into the evolution and social bonding of musicality, but is so broad and sweeping it will be challenging to test, prove or falsify in the Popperian sense (Popper, 1959). After general comments, I focus my critique on underlying neurobiological mechanisms, and offer some suggestions for experimental tests of MSB.

The hypothesis that music is well suited to facilitate social bonding (Savage et al., target article) is highly consistent with social psychological research on the need to belong. We explore how music is uniquely placed to increase feelings of connections to large collectives by increasing collective effervescence, providing narratives, reminding one of others, and providing social surrogates.

Music's efficacy as a credible signal and/or as a tool for social bonding piggybacks on a diverse set of biological and cognitive processes, implying different proximate mechanisms. It is likely this multiplicity of mechanisms that explains why it is so difficult to account for music's putative biological role(s), as well as its possible origins, by proposing a single adaptive function.

Music uses the evolutionarily unique temporal sensitivity of the auditory system and its tight coupling to the motor system to create a common neurophysiological clock between individuals that facilitates action coordination. We propose that this shared common clock arises from entrainment to musical rhythms, the process by which partners' brains and bodies become temporally aligned to the same rhythmic pulse.

Both target papers cite evidence from infancy and early childhood to support the notion of human musicality as a somewhat static suite of capacities; however, in our view they do not adequately acknowledge the critical role of developmental timing, the acquisition process, or the dynamics of social learning, especially during later periods of development such as middle childhood.

Despite acknowledging that musicality evolved to serve multiple adaptive functions in human evolution, Savage et al. promote social bonding to an overarching super-function. Yet, no unifying neurobiological framework is offered. We propose that oxytocin constitutes a socio-allostatic agent whose modulation of sensing, learning, prediction, and behavioral responses with reference to the physical and social environment facilitates music's social bonding effects.

Savage et al. and Mehr et al. provide well-substantiated arguments that the evolution of musicality was shaped by adaptive functions of social bonding and credible signalling. However, they are too quick to dismiss byproduct explanations of music evolution, and to present their theories as complete unitary accounts of the phenomenon.

Comparative studies of primates indicate that humans have evolved unique motivations and cognitive skills for sharing emotions, experiences, and collaborative actions. Given the characteristics of music, the music and social bonding (MSB) hypothesis by Savage et al. fits this view. Within a cross-species approach, predispositions not observed in current communication system may contribute to a better understanding of the biological roots of human musicality.

The two target articles address the origins of music in complementary ways. However, both proposals focus on overt musical behaviour, largely ignoring the role of perception and cognition, and they blur the boundaries between the potential origins of language and music. To resolve this, an alternative research strategy is proposed that focuses on the core cognitive components of musicality.

The category “music” as used in this area of science is inconsistent and unstable, and its logical relationship to the word “musicality” – used by scientists to denote the human capacity for music – is circular. Therefore, rather than pursue the question, “Why did music(ality) evolve?” let us ask more inclusively, “What experiences in humankind's deep past might have felt like music?”

I support the music and social bonding (MSB) framework, but submit that the authors' predictions lack discriminative power, and that they do not engage sufficiently with the emotion mechanisms that mediate between musical features and social bonding. I elaborate on how various mechanisms may contribute, in unique ways, to social bonding at various levels to help account for the socio-emotional effects of music.