Juslin & Vastfjall's (J&V) work represents an important step forward in our understanding of the proximate mechanisms involved in emotional responses to music. What is missing from their model, however, is an overarching evolutionary theory that coherently integrates the ontogenetic, neuropsychological, and cultural elements identified by the authors into an adaptive whole capable of explaining not only how, but also why we have such strong, emotional responses to music.

As noted by the authors, humans appear to be genetically predisposed to respond to music. Changes in pulse, respiration, heart rate, skin conductance, motor patterns, neuroendocrine response, and even immunological function can be induced by music (Harrer & Harrer Reference Harrer, Harrer, Critchley and Henson1977; Hirokawa & Ohira Reference Hirokawa and Ohira2003; Khalfa et al. Reference Khalfa, Dalla Bella, Roy, Peretz and Lupien2003). Like the ritualized displays of many nonhuman species, the formality, pattern, sequence, and repetition of human music appears to engage basic brain functions, including brain stem, limbic, and cortical regions, and to activate specific pathways related to autonomic, emotional, and motor behaviors (Blood & Zatorre Reference Blood and Zatorre2001; Patel Reference Patel2008). In nonhuman species, ritualized displays serve to communicate reliable information between sender and receiver regarding the sender's condition, intention, and motivation (Alcock Reference Alcock2005). This information impacts the autonomic, endocrine, and behavioral responses of the receiver, ultimately engendering either approach or withdrawal responses. Music clearly elicits similar neurophysiological responses in humans. In contrast to nonhuman ritual, however, music amplifies and symbolically abstracts the component elements of ritual, thereby providing a transformative mechanism for engendering and entraining specific autonomic and emotional responses across groups of individuals, as well as across time and space.

Patel has noted “humans are the only species to spontaneously synchronize to the beat of music” (2008, p. 100). Such musically induced synchronization promotes congruent motor and autonomic responses which, in turn, impact both emotions and subconscious social judgment and decision-making (Bargh et al. Reference Bargh, Chen and Burrows1996; Bar-On et al. Reference Bar-On, Tranel, Denburg, Bechara, Cacioppo and Berntson2005; Clore & Huntsinger Reference Clore and Huntsinger2007; Damasio Reference Damasio1994). These congruent states, and the mirror neuron activation they are likely to initiate, have been positively correlated with empathy (Carr et al. Reference Carr, Iacoboni, Charlotte-Dubeau, Mazziotta, Lenzi, Cacioppo and Berntson2005; Levenson Reference Levenson, Ekman, Campos, Davidson and de Waal2003), an important building block of both inter-individual trust and social cooperation. It is important to note, however, that not all human emotional responses to music are universal. Many of the emotions evoked by music are culturally specific, suggesting an important role for learning in the development of musico-emotional associations.

The inclusion of ontogenetic factors in emotional responses to music is a significant contribution of the target article. Recent findings regarding brain plasticity and the role of experiential influences on the development of neural networks, particularly during adolescence and infancy (Giedd et al. Reference Giedd, Blumenthal, Jeffries, Catellanos, Liu, Zijdenbos, Paus, Evans and Rapoport1999; Koelsch et al. Reference Koelsch, Fritz, Schulze, Alsop and Schlaug2005), offer important insights into how genetic predispositions for music may be shaped through socialization processes. Music is at once individual and social, innate and learned (Cross Reference Cross, Avanzini, Faienza, Minciacchi, Lopez and Majno2003). Universal human pitch preferences and an innate sensitivity to consonance and dissonance (Hannon & Trainor Reference Hannon and Trainor2007) set the stage for developing musical expectancy. Throughout the world, newborns prefer song to speech, particularly songs that are slower, higher-pitched, and exaggerated in rhythm (Trehub Reference Trehub, Zatorre and Peretz2001). Such songs are likely to optimize the autonomic and motor entrainment of infant and caregiver, thereby contributing to empathic attachment. During childhood, these innate musical preferences and capacities are channeled and elaborated into specific cultural forms. By age 6, children readily employ both tempo and mode in the music of their cultures to identify basic emotions of happiness, sadness, fear, and anger (Trehub Reference Trehub, Zatorre and Peretz2001). By age 10, they are able to identify and neurologically respond to syntactic irregularities in the music of their culture (Koelsch et al. Reference Koelsch, Fritz, Schulze, Alsop and Schlaug2005).

It is during adolescence, however, that emotional response to music seems to peak. Adolescent brain changes, including the heightened activity of limbic and dopaminergic reward systems, and the maturation of temporal and prefrontal cortices (Spear Reference Spear2000), are likely to drive this heightened emotional response to music. Simultaneously, many of the brain areas activated by music, including the amygdala, insula, anterior cingulate cortex, prefrontal cortex, and superior temporal sulcus (Blood & Zatorre Reference Blood and Zatorre2001; Koelsch et al. Reference Koelsch, Fritz, Schulze, Alsop and Schlaug2005), are also integral to social cognition and behavior (Blakemore Reference Blakemore2008). The synaptic pruning and myelination occurring throughout these brain regions during adolescence make this a particularly sensitive developmental period for creating associational networks across sensory, social, and symbolic domains. Simultaneous shifts in the dopaminergic reward system of the adolescent brain, and heightened amygdala activity, provide unique opportunities for the “evaluative conditioning” proposed by J&V (Alcorta Reference Alcorta and McNamara2006; Alcorta & Sosis Reference Alcorta and Sosis2005). It is becoming increasingly clear that brain stem reflexes (Boso et al. Reference Boso, Politi, Barale and Emanuele2007), musical expectancy (Huron Reference Huron2006; Koelsch et al. Reference Koelsch, Fritz, Schulze, Alsop and Schlaug2005), emotional contagion (Hatfield et al. Reference Hatfield, Cacioppo and Rapson1994; Juslin Reference Juslin, Juslin and Sloboda2001), and evaluative conditioning (De Houwer et al. Reference De Houwer, Thomas and Baeyens2001) all have important roles to play in the ontogenetic development of neural networks linking the sensory stimuli of music with motor, cognitive, emotional, and social functions.

Although such evaluative conditioning may result in the emotional “tagging” of music as the authors propose, we believe that the converse – that is, the evaluative conditioning of neutral stimuli through association with emotionally evocative music – is likely to be the more frequent and evolutionarily adaptive response (Alcorta, in press). The intimate association of music and religious ritual across all cultures, and the cross-cultural prevalence of religious rites of passage during adolescence (Alcorta Reference Alcorta and McNamara2006; Reference Alcorta, Bulbulia, Sosis, Harris, Genet, Genet and Wyman2008), suggest an important role for music in the evaluative conditioning of religious beliefs and symbols. Emotional responses to music may be instrumental in imbuing abstract symbols and beliefs with sacred and motivational meaning, particularly during adolescence. Brain-imaging data have demonstrated activation of the brain's reward circuitry in response to familiar music (Blood & Zatorre Reference Blood and Zatorre2001; Menon & Levitin Reference Menon and Levitin2005). The ability of music to engender and entrain autonomic responses, evoke emotions, engage reward circuitry, elicit empathy, and associate motivational responses with socially salient stimuli renders it a powerful emotive and mnemonic mechanism for creating cohesive groups among non-kin.

The social salience of music receives only passing attention in the target article. The authors largely limit their scope to contemporary secular music and consider music principally from the perspective of the individual listener. Yet, historically and cross-culturally music is neither individual nor secular (Alcorta, in press; Becker Reference Becker, Juslin and Sloboda2001; Reference Becker2004). Music has been and continues to be intimately associated with communal and religious ritual in societies as diverse as Australian hunter-gatherers, African agriculturalists, and American industrialists. In traditional societies, the relationship between music and religion is not only intimate, but often inseparable (Becker Reference Becker, Juslin and Sloboda2001). Even in modern, secular societies, music continues to play a fundamental role in both communal (Huron Reference Huron, Peretz and Zatorre2003) and religious ritual (Chaves et al. Reference Chaves, Konieszny, Beyerlein and Barman1999). This close relationship between sociality, sanctity, and music offers important insights into emotional responses to music and suggests possible adaptive functions for those responses that shed light on both proximate and ultimate causes (Alcorta & Sosis Reference Alcorta and Sosis2005).

J&V assert that “most emotional reactions to music do not involve implications for goals in life” (target article, sect. 1, para. 7, emphasis theirs). However, just as we may be largely unaware of the subconscious processes that drive many of our life choices (Bargh et al. Reference Bargh, Chen and Burrows1996; Damasio Reference Damasio1994), we are also likely to be consciously unaware of the life goals involved in emotional reactions to music. There is strong psychological, neurological, ontogenetic, and cross-cultural evidence to suggest that our emotional reactions to music have important and far-reaching adaptive implications for our beliefs, goals, and actions as members of social and cultural groups.