Hypotheses about the origin of music frequently mention the importance of maternal singing, as in soothing lullabies, which is virtually universal. However, studies by developmental psychologists of playful face-to-face interactions between mothers and infants of 4 weeks to 6 months of age show that a mother's vocalizations are more complex than “singing.” They are embedded in a multimodal package that includes her facial expressions and head and body movements, as well as singsong vocalizations.
Microanalyses of these early interactions reveal that the behavior and affect of both partners are temporally organized, thereby emotionally coordinating or “attuning” the pair (Beebe, Reference Beebe and Key1982; Jaffe, Beebe, Feldstein, Crown, & Jasnow, Reference Jaffe, Beebe, Feldstein, Crown and Jasnow2001, pp. 13–14; Stern, Reference Stern1985; Trevarthen, Reference Trevarthen1999). Infants as young as 4–8 weeks expect social contingency. That is revealed by dual-video recordings of face-to-face interactions on television screens in separate rooms. After 2 min of normal ongoing play, the mother's film is desynchronized (replayed) so that the infant now sees her earlier behavior that had just been engaging and delightful. However, it quickly realizes that something is wrong and shows signs of psychological distress such as averted gaze, closed mouth, frowning, fingering of clothing, and the displacement activity of yawning (Murray & Trevarthen, Reference Murray, Trevarthen, Field and Fox1985; Nadel, Carchon, Kervella, Marcelli, & Reserbet-Planty, Reference Nadel, Carchon, Kervella, Marcelli and Reserbet-Planty1999).
This emotional/behavioral coordination is more than “social.” It is relational, and has developmental benefits and adaptive implications. Neurobiologists describe the pathological effects to infants of deficient early interactive exchanges (Aitken & Trevarthen, Reference Aitken and Trevarthen1997; Koulomzin et al., Reference Koulomzin, Beebe, Anderson, Jaffe, Feldstein and Crown2002; Schore, Reference Schore1994; Trevarthen & Aitken, Reference Trevarthen and Aitken1994), corroborating psychologists' findings about the importance of positive intimate multimodal early interactions to beneficial outcomes in later (post-infant) life.
These early interaction findings support the music as social bonding (MSB) hypothesis by adding to it (a) the psychobiological (and presumably evolutionary) importance of maternal facial, head, and body movements (not only “singing”) in the earliest mother–infant interactions; (b) the creation and reinforcement of emotional bonding (not only “infant mood regulation”) by the temporal coordination achieved and reinforced by the attendant neurochemical mechanisms the authors describe; and (c) the infant's contribution to (participation in) the multimodal exchange, as its own behavior affects the mother's changing vocal, facial, and gestural dynamics of faster–slower, louder–softer, larger–smaller, wider–narrower and so forth, which she produces according to her perception of her infant's emotional/behavioral state.
The authors describe “neurobiological proximate mechanisms,” as “underpinning musicality's social effects” and occurring “between infant and mother, mates, and among members of groups.” Because oxytocin and other endogenous opioids are released during parturition, lactation, and maternal caring behavior in mammals, it is plausible that these emotionally rewarding prosocial mechanisms would have been used, and augmented, to address an adaptive problem in ancestral humans: ensuring maternal care of highly altricial (helpless) infants who need months and years of care. The coevolved creation of and response to ritualized facial, bodily, and vocal signals of affiliative intent by ancestral mother–infant pairs physically coordinated and emotionally bonded them. A successful bond would have helped to assure both infant survival and maternal reproductive success.
Looked at in this way, it is mother–infant mutuality that is the adaptation and musicality can be considered an exaptation (not a byproduct) that, as the “set of capabilities that can be utilized in different ways to support multiple functions, all involving social effects,” appears universally in all societies in culturally varied ways. Musicality as a set of capacities that was prefigured in early interactions need not have been only, as the MSB authors suggest, a “cultural ‘invention’” or “byproduct” of other adaptations but an evolved predisposition to use these capacities according to the different lifeways of varied cultural groups.
This scenario also challenges some of the assumptions and assertions of the authors of the credible signaling hypothesis (MCS) as applied to infant care – that is, that infant-directed song is primarily a coevolved system for credibly signaling parental attention to secondarily altricial infants. The authors of the hypothesis mention affective prosody of mothers to infants – calling it “manipulative” – but do not take account of the whole reciprocal package in early mother–infant interactions that emotionally bonds the pair by means of facial and gestural as well as vocal components (and also includes touch). These early interactions do not only “communicate information” but express and exchange signals of shared positive emotional intent and accord, apart from whatever overt or covert information the mother might also communicate about what is in her mind.
The MCS hypothesis rests upon competition and territoriality, and parent–infant conflict. The authors emphasize that in ancestral societies (and presumably, later, in other small-scale societies), mothers were required to simultaneously care for multiple dependent offspring and that infants had to compete with multiple juveniles for the attention of multiple caregivers. Accounts of infancy in small-scale societies (e.g., Eibl-Eibesfeldt, Reference Eibl-Eibesfeldt1989, p. 215; Field, Sostek, Vietze, & Leidermann, Reference Field, Sostek, Vietze and Leidermann1981; Hrdy, Reference Hrdy2009; Leiderman, Tuckerman, & Rosenfeld, Reference Leiderman, Tuckerman and Rosenfeld1977) suggest that crying and care-eliciting distress vocalizations by infants are rare, as babies are usually carried or otherwise attached to the mother's body or handed to another person – older siblings, cousins, grandparents.
The authors of MCS are rightly concerned that hypotheses about a behavior's adaptive value present evidence of design, distinguishing between proximate and ultimate benefits.
As I describe, the original adaptive problem was to insure maternal care of unprecedently altricial human infants, thereby assuring the ultimate benefits of infant survival and maternal reproductive success. The solution was to co-opt the dopaminergic reward system and produce oxytocin and other opioids (that already underlay mammalian maternal behavior) for use in proximately rewarding face-to-face interactions.
In addition to the mother's ritualized (enhanced, emphasized) facial, bodily, and vocal signals of accord, the interactions became more temporally coordinated and more emotionally rewarding, ultimately bonding the pair.
Let us assume that in small bands of hominins it would be adaptive for individuals in a fractious group to become periodically bonded – physically and emotionally coordinated – and thereby predisposed to cooperate in common cause. Mother–infant early interactions already provided rewarding neurophysiological mechanisms that accompanied ritualized and temporally coordinated vocal and movement modalities to the end of bonding. These could have been developed in group rituals, such as feasting, with its multimodal components of music, dance, costume, ornament, and so forth, as the authors of MCS describe (see Dissanayake, Reference Dissanayake, Renfrew, Morley and Boyd2018, pp. 91–93, for detailed discussion of the development of ritual and ceremonial behavior in ancestral humans).
With this scenario – music(ality)'s origins in biobehavioral predispositions that originated in adaptive ancestral mother–infant interactions – other suggested evolutionary hypotheses of music's function can fit under one umbrella. One can emphasize either a cooperative or competitive outcome – social bonding, sexual or social or territorial display, credible signaling, or other possibilities – any one or all of which may exist within one group. Considering music in this way as an exaptation supports the emphasis in both articles on cultural evolution as explaining music's many different appearances around the world. All retain the original features of early interactions, as described above.
Hypotheses about the origin of music frequently mention the importance of maternal singing, as in soothing lullabies, which is virtually universal. However, studies by developmental psychologists of playful face-to-face interactions between mothers and infants of 4 weeks to 6 months of age show that a mother's vocalizations are more complex than “singing.” They are embedded in a multimodal package that includes her facial expressions and head and body movements, as well as singsong vocalizations.
Microanalyses of these early interactions reveal that the behavior and affect of both partners are temporally organized, thereby emotionally coordinating or “attuning” the pair (Beebe, Reference Beebe and Key1982; Jaffe, Beebe, Feldstein, Crown, & Jasnow, Reference Jaffe, Beebe, Feldstein, Crown and Jasnow2001, pp. 13–14; Stern, Reference Stern1985; Trevarthen, Reference Trevarthen1999). Infants as young as 4–8 weeks expect social contingency. That is revealed by dual-video recordings of face-to-face interactions on television screens in separate rooms. After 2 min of normal ongoing play, the mother's film is desynchronized (replayed) so that the infant now sees her earlier behavior that had just been engaging and delightful. However, it quickly realizes that something is wrong and shows signs of psychological distress such as averted gaze, closed mouth, frowning, fingering of clothing, and the displacement activity of yawning (Murray & Trevarthen, Reference Murray, Trevarthen, Field and Fox1985; Nadel, Carchon, Kervella, Marcelli, & Reserbet-Planty, Reference Nadel, Carchon, Kervella, Marcelli and Reserbet-Planty1999).
This emotional/behavioral coordination is more than “social.” It is relational, and has developmental benefits and adaptive implications. Neurobiologists describe the pathological effects to infants of deficient early interactive exchanges (Aitken & Trevarthen, Reference Aitken and Trevarthen1997; Koulomzin et al., Reference Koulomzin, Beebe, Anderson, Jaffe, Feldstein and Crown2002; Schore, Reference Schore1994; Trevarthen & Aitken, Reference Trevarthen and Aitken1994), corroborating psychologists' findings about the importance of positive intimate multimodal early interactions to beneficial outcomes in later (post-infant) life.
These early interaction findings support the music as social bonding (MSB) hypothesis by adding to it (a) the psychobiological (and presumably evolutionary) importance of maternal facial, head, and body movements (not only “singing”) in the earliest mother–infant interactions; (b) the creation and reinforcement of emotional bonding (not only “infant mood regulation”) by the temporal coordination achieved and reinforced by the attendant neurochemical mechanisms the authors describe; and (c) the infant's contribution to (participation in) the multimodal exchange, as its own behavior affects the mother's changing vocal, facial, and gestural dynamics of faster–slower, louder–softer, larger–smaller, wider–narrower and so forth, which she produces according to her perception of her infant's emotional/behavioral state.
The authors describe “neurobiological proximate mechanisms,” as “underpinning musicality's social effects” and occurring “between infant and mother, mates, and among members of groups.” Because oxytocin and other endogenous opioids are released during parturition, lactation, and maternal caring behavior in mammals, it is plausible that these emotionally rewarding prosocial mechanisms would have been used, and augmented, to address an adaptive problem in ancestral humans: ensuring maternal care of highly altricial (helpless) infants who need months and years of care. The coevolved creation of and response to ritualized facial, bodily, and vocal signals of affiliative intent by ancestral mother–infant pairs physically coordinated and emotionally bonded them. A successful bond would have helped to assure both infant survival and maternal reproductive success.
Looked at in this way, it is mother–infant mutuality that is the adaptation and musicality can be considered an exaptation (not a byproduct) that, as the “set of capabilities that can be utilized in different ways to support multiple functions, all involving social effects,” appears universally in all societies in culturally varied ways. Musicality as a set of capacities that was prefigured in early interactions need not have been only, as the MSB authors suggest, a “cultural ‘invention’” or “byproduct” of other adaptations but an evolved predisposition to use these capacities according to the different lifeways of varied cultural groups.
This scenario also challenges some of the assumptions and assertions of the authors of the credible signaling hypothesis (MCS) as applied to infant care – that is, that infant-directed song is primarily a coevolved system for credibly signaling parental attention to secondarily altricial infants. The authors of the hypothesis mention affective prosody of mothers to infants – calling it “manipulative” – but do not take account of the whole reciprocal package in early mother–infant interactions that emotionally bonds the pair by means of facial and gestural as well as vocal components (and also includes touch). These early interactions do not only “communicate information” but express and exchange signals of shared positive emotional intent and accord, apart from whatever overt or covert information the mother might also communicate about what is in her mind.
The MCS hypothesis rests upon competition and territoriality, and parent–infant conflict. The authors emphasize that in ancestral societies (and presumably, later, in other small-scale societies), mothers were required to simultaneously care for multiple dependent offspring and that infants had to compete with multiple juveniles for the attention of multiple caregivers. Accounts of infancy in small-scale societies (e.g., Eibl-Eibesfeldt, Reference Eibl-Eibesfeldt1989, p. 215; Field, Sostek, Vietze, & Leidermann, Reference Field, Sostek, Vietze and Leidermann1981; Hrdy, Reference Hrdy2009; Leiderman, Tuckerman, & Rosenfeld, Reference Leiderman, Tuckerman and Rosenfeld1977) suggest that crying and care-eliciting distress vocalizations by infants are rare, as babies are usually carried or otherwise attached to the mother's body or handed to another person – older siblings, cousins, grandparents.
The authors of MCS are rightly concerned that hypotheses about a behavior's adaptive value present evidence of design, distinguishing between proximate and ultimate benefits.
As I describe, the original adaptive problem was to insure maternal care of unprecedently altricial human infants, thereby assuring the ultimate benefits of infant survival and maternal reproductive success. The solution was to co-opt the dopaminergic reward system and produce oxytocin and other opioids (that already underlay mammalian maternal behavior) for use in proximately rewarding face-to-face interactions.
In addition to the mother's ritualized (enhanced, emphasized) facial, bodily, and vocal signals of accord, the interactions became more temporally coordinated and more emotionally rewarding, ultimately bonding the pair.
Let us assume that in small bands of hominins it would be adaptive for individuals in a fractious group to become periodically bonded – physically and emotionally coordinated – and thereby predisposed to cooperate in common cause. Mother–infant early interactions already provided rewarding neurophysiological mechanisms that accompanied ritualized and temporally coordinated vocal and movement modalities to the end of bonding. These could have been developed in group rituals, such as feasting, with its multimodal components of music, dance, costume, ornament, and so forth, as the authors of MCS describe (see Dissanayake, Reference Dissanayake, Renfrew, Morley and Boyd2018, pp. 91–93, for detailed discussion of the development of ritual and ceremonial behavior in ancestral humans).
With this scenario – music(ality)'s origins in biobehavioral predispositions that originated in adaptive ancestral mother–infant interactions – other suggested evolutionary hypotheses of music's function can fit under one umbrella. One can emphasize either a cooperative or competitive outcome – social bonding, sexual or social or territorial display, credible signaling, or other possibilities – any one or all of which may exist within one group. Considering music in this way as an exaptation supports the emphasis in both articles on cultural evolution as explaining music's many different appearances around the world. All retain the original features of early interactions, as described above.