The proposal that language has evolved to conform to general cognitive and learning constraints inherent in the human brain calls for specification of these mechanisms. We propose that just as cognition appears to be grounded in cross-modal perceptual-motor capabilities, so too must language. Evidence for perceptual-motor grounding comes from non-arbitrary sound-to-meaning correspondences and their role in word learning.

We suggest there is somewhat more potential than Christiansen & Chater (C&C) allow for genetic adaptations specific to language. Our uniquely cooperative social system requires sophisticated language skills. Learning and performance of some culturally transmitted elements in animals is genetically based, and we give examples of features of human language that evolve slowly enough that genetic adaptations to them may arise.

Christiansen & Chater (C&C) have taken the interactionist approach to linguistic universals to an extreme, adopting the metaphor of language as an organism. This metaphor adds no insights to five decades of analyzing language universals as the result of interaction of linguistically unique and general cognitive systems. This metaphor is also based on an outmoded view of classical Darwinian evolution and has no clear basis in biology or cognition.

I identify a number of problematic aspects of Christiansen & Chater's (C&C's) contribution. These include their suggestion that subjacency and binding reflect non-domain-specific mechanisms; that proto-language is a “cultural product”; and that non-adaptationism requires overly rich innate structures, and is incompatible with acceptable evolutionary processes. It shows that a fully UG (Universal Grammar)-free version of the authors' neo-adaptationism would be incoherent.

Christiansen & Chater (C&C) focus solely on general-purpose cognitive processes in their elegant conceptualization of language evolution. However, numerous developmental facts attested in L1 acquisition confound C&C's subsequent claim that the logical problem of language acquisition now plausibly recapitulates that of language evolution. I argue that language acquisition should be viewed instead as a multi-layered construction involving the interplay of general and domain-specific learning mechanisms.

We agree that language adapts to the brain, but we note that language also has to adapt to brain-external constraints, such as those arising from properties of the cultural transmission medium. The hypothesis that Christiansen & Chater (C&C) raise in the target article not only has profound consequences for our understanding of language, but also for our understanding of the biological evolution of the language faculty.

Christiansen & Chater (C&C) suggest that language is itself an evolutionary system, and that natural languages “evolve” to be easy to learn and process. The tight economy of the world's case-marking systems lends support to this hypothesis. Only two major case systems occur, cross-linguistically, and noun phrases are seldom overtly case-marked wherever zero-marking would be functionally practical.

Though we agree with their argument that language is shaped by domain-general learning processes, Christiansen & Chater (C&C) neglect to detail how the development of these processes shapes language change. We discuss a number of examples that show how developmental processes at multiple levels and timescales are critical to understanding the origin of domain-general mechanisms that shape language evolution.

Language learning is not primarily driven by a motivation to describe invariant features of the world, but rather by a strong force to be a part of the social group, which by definition is not invariant. It is not sufficient for language to be fit for the speaker's perceptual motor system. It must also be fit for social interactions.

Our target article argued that a genetically specified Universal Grammar (UG), capturing arbitrary properties of languages, is not tenable on evolutionary grounds, and that the close fit between language and language learners arises because language is shaped by the brain, rather than the reverse. Few commentaries defend a genetically specified UG. Some commentators argue that we underestimate the importance of processes of cultural transmission; some propose additional cognitive and brain mechanisms that may constrain language and perhaps differentiate humans from nonhuman primates; and others argue that we overstate or understate the case against co-evolution of language genes. In engaging with these issues, we suggest that a new synthesis concerning the relationship between brains, genes, and language may be emerging.

Research indicates that people value music primarily because of the emotions it evokes. Yet, the notion of musical emotions remains controversial, and researchers have so far been unable to offer a satisfactory account of such emotions. We argue that the study of musical emotions has suffered from a neglect of underlying mechanisms. Specifically, researchers have studied musical emotions without regard to how they were evoked, or have assumed that the emotions must be based on the “default” mechanism for emotion induction, a cognitive appraisal. Here, we present a novel theoretical framework featuring six additional mechanisms through which music listening may induce emotions: (1) brain stem reflexes, (2) evaluative conditioning, (3) emotional contagion, (4) visual imagery, (5) episodic memory, and (6) musical expectancy. We propose that these mechanisms differ regarding such characteristics as their information focus, ontogenetic development, key brain regions, cultural impact, induction speed, degree of volitional influence, modularity, and dependence on musical structure. By synthesizing theory and findings from different domains, we are able to provide the first set of hypotheses that can help researchers to distinguish among the mechanisms. We show that failure to control for the underlying mechanism may lead to inconsistent or non-interpretable findings. Thus, we argue that the new framework may guide future research and help to resolve previous disagreements in the field. We conclude that music evokes emotions through mechanisms that are not unique to music, and that the study of musical emotions could benefit the emotion field as a whole by providing novel paradigms for emotion induction.

Whether and how music is involved in evoking emotions is a matter of considerable debate. In the target article, Juslin & Västfjäll (J&V) argue that music induces a wide range of both basic and complex emotions that are shared with other stimuli. If such a link exists, it would provide a common basis for considering the interactions among music, emotion, timing, and time perception.

Juslin & Västfjäll (J&V) advance our understanding of the proximate mechanisms underlying emotional responses to music, but fail to integrate their findings into a comprehensive evolutionary model that addresses the adaptive functions of these responses. Here we offer such a model by examining the ontogenetic relationship between music, ritual, and symbolic abstraction and their role in facilitating social coordination and cooperation.

Juslin & Västfjäll's (J&V's) discussions of evaluative conditioning and episodic memory focus on circumstances in which music becomes associated with arbitrary life events. However, analyses of film music suggest that viewers experience consistent pairings between types of music and types of narrative content. Researchers have demonstrated that the emotional content of film music has a major impact on viewers' emotional experiences of a narrative.

We propose three extensions of the theory developed by Juslin & Västfjäll (J&V). First, motion should be considered as an additional mechanism. Second, synchronization plays a role in eliciting emotion. And, third, the spectrum of musical affect or feelings is denser and broader than the spectrum of emotions, suggesting an expansion of the scope of the theory beyond emotions.

We suggest that semantic association may be a further mechanism by which music may elicit emotion. Furthermore, we note that emotional contagion is not always an immediate process requiring little prior information processing; rather, emotional contagion contributing to music processing may constitute a more complex decoding mechanism for information inherent in the music, which may be subject to a time course of activation.

In the target article, Juslin & Västfjäll (J&V) contend that neural mechanisms not unique to music are critical to its capability to convey emotion. The work reviewed here provides a broader context for this proposal. Human abilities to signal emotion through sound could have been essential to human evolution, and may have contributed vital foundations for music. Future learning experiments are needed to further clarify engagement underlying musical and broader emotional signaling.

Juslin & Västfjäll (J&V) propose a theoretical framework of how music may evoke an emotional response. This commentary presents results from a pilot study that employed young children as participants, and measured musically induced emotions through facial expressions. Preliminary findings support certain aspects of the proposed theoretical framework. The implications of these findings on future research employing the proposed framework are discussed.

Key premises of the target article by Juslin & Västfjäll (J&V) are challenged. It is also shown that most of the six “psychological mechanisms” proposed by the authors as underlying the induction of emotion by music involve nonmusical proximal causes. As a replacement for “musical emotions,” the state of being-moved – from the recently developed Aesthetic Trinity Theory – is proposed.

When examining how emotions are evoked through music, the role of musical expectancy is often surprisingly under-credited. This mechanism, however, is most strongly tied to the actual structure of the music, and thus is important when considering how music elicits emotions. We briefly summarize Leonard Meyer's theoretical framework on musical expectancy and emotion and cite relevant research in the area.