Computational modeling of the macaque brain grounds hypotheses on the brain of LCA-m (the last common ancestor of monkey and human). Elaborations thereof provide a brain model for LCA-c (c for chimpanzee). The Mirror System Hypothesis charts further steps via imitation and pantomime to protosign and protolanguage on the path to a "language-ready brain" inHomo sapiens,with the path to speech being indirect. The material poses new challenges for both experimentation and modeling.

In this paper, I argue that an important component of the language-ready brain is the ability to recognize and conceptualize events. By ‘event’, I mean any situation or activity in the world or our mental life, that we find salient enough to individuate as a thought or word. While this may sound either trivial or non-unique to humans, I hope to show that abstracting away events and their participants from the embodied flow of experience is a characteristic unique to humans. (...) This ability is enabled, I will argue, by two critical competencies that act as scaffolds for language-ready thought in the prehuman brain. The first, as argued by Arbib (2006,2012,2016) and others, is a sophisticated system of gesture production and understanding in prehumans, which provided a template for schema-like sequencing and slot-filling of information units. The second involves the integration of multiple modalities of expression in the communicative act, in particular, the alignment of co-gestural speech and co-speech gesture. With such computational facilities, action-based gestures can be abstracted away from their associated objects and become full event representations. This view supports the MSH argument for the emergence of more complex linguistic expressions from initially holophrastic units. In particular, actions can be thought of as protoverbs, which through this process are abstracted to full event descriptions, i.e., verbs. (shrink)

I argue that a critical feature of language that distinguishes it from animal communication isdisplacement,the means to communicate about the non-present. This implies a capacity for mental travels in time and space, which is the ability to call to mind past episodes, imagine future ones or purely fictitious ones, and locate them in different places. While mental travel in time, in particular, is often considered to be unique to humans, behavioral and neurophysiological evidence suggests that it is evident in some (...) form, at least, in nonhuman animals, including rodents, and may go far back in the evolution of animals that move. The linguistic capacity to share experiences that transcend space and time evolved much more recently, accelerating during the Pleistocene with increasing demands for effective cooperation and long-distance planning. The expansion of mental time travel probably co-evolved with the development of language itself, because the sharing of memories, plans, and stories vastly added to our own individual experiences. From this perspective, the critical period of the Road Map runs from the emergence of the genusHomoaround 2 million years ago to the present. (shrink)

Cognitive and emotional processes are now known to be intertwined and thus the limbic system that underlies emotions is important for human brain evolution, including the evolution of circuits supporting language. The neural substrates of limbic functions, like motivation, attention, inhibition, evaluation, detection of emotional stimuli and others have changed over time. Even though no new, added structures are present in the human brain compared to nonhuman primates, evolution tweaks existing structural systems with possible functional implications. Empirical comparative neuroanatomical evidence (...) is presented here in support of such changes in the limbic system, including the amygdala and the orbitofrontal cortex. Given their possible functional significance, these alterations may further enable and enhance human interest and motivation to communicate beyond what is seen in other primates living in complex social groups. The argument here is that even though emotion processing is likely needed for increased social complexity independent of language, the reason why humans want to talk may be related in part to the enhancement of socioemotional processes resulting from the reorganization and rewiring of underlying neural systems some of which are interconnected to the language areas. Neurodevelopmental disorders in humans affecting both language and sociability fuel such arguments. (shrink)

We used optical neuroimaging to explore the extent of functional overlap between working memory (WM) networks involved in language and Early Stone Age toolmaking behaviors. Oldowan tool production activates two verbal WM areas, but the functions of these areas are indistinguishable from general auditory WM, suggesting that the first hominin toolmakers relied on early precursors of verbal WM to make simple flake tools. Early Acheulian toolmaking elicits activity in a region bordering on Broca’s area that is involved in both visual (...) and verbal WM tasks. The sensorimotor and mirror neurons in this area, along with enhancement of general WM capabilities around 1.8 million years ago, may have provided the scaffolding upon which a WM network dedicated to processing exclusively linguistic information could evolve. In the road map going forward, neuro-archaeologists should investigate the trajectory of WM over the course of human evolution to better understand its contribution to language origins. (shrink)

It is now generally accepted that the motor system is not purely dedicated to the control of behavior, but also has cognitive functions. Mirror neurons have provided a new perspective on how sensory information regarding others’ actions and gestures is coupled with the internal cortical motor representation of them. This coupling allows an individual to enrich his interpretation of the social world through the activation of his own motor representations. Such mechanisms have been highly preserved in evolution as they are (...) present in humans, apes and monkeys. Recent neuroanatomical data showed that there are two different connectivity patterns in mirror neuron networks in the macaque: one is concerned with sensorimotor transformation in relation to reaching and hand grasping within the traditional parietal-premotor circuits; the second one is linked to the mouth/face motor control and the new data show that it is connected with limbic structures. The mouth mirror sector seems to be wired not only for ingestive behaviors but also for orofacial communicative gestures and vocalizations. Notably, the hand and mouth mirror networks partially overlap, suggesting the importance of hand-mouth synergies not only for sensorimotor transformation, but also for communicative purposes in order to better convey and control social signals. (shrink)

Comparative approaches to language evolution are essential but cannot by themselves resolve the timing and context of evolutionary events since the last common ancestor with chimpanzees. Archaeology can help to fill this gap, but only if properly integrated with evolutionary theory and the ethnographic, ethological, and experimental analogies required to reconstruct the broader social, behavioral, and neurocognitive implications of ancient artifacts. The current contribution elaborates a technological pedagogy hypothesis of language origins by developing the concept of an evolving human technological (...) niche and applying it to investigate two key transitions posited by Arbib’s Mirror System Hypothesis: from complex action recognition and imitation to proto-language, and from proto-language to language. (shrink)

This paper outlines how the focus on how communicative signals might emerge and how the capacity to interpret them might develop, does not yet explain what type of motivation is required to actually deal with those signals. Without the consistent production of appropriate responses to the production of communicative signals, there would be no point in producing any signal. If language is a tool to accomplish things with others, we need to understand what would lead to cooperation. The first step (...) consists in avoiding the blind belief that all cooperation requires some prosocial attitude. A great deal of cooperation can occur while each participant in the interaction is selfishly attempting to maximize their own benefits or minimizing damaging consequences.I describe how different types of turn-taking can be achieved via different levels of cognitive complexity and how interpretive turn-taking requires a great deal of cognitive abilities that great apes possess. Finally, I provide empirical evidence of social manipulation in non-human primates. Given our awareness of the occurrence of social manipulation during cooperation among human adults, it seems necessary to reconsider to what degree human communication and language evolution require unique prosocial motivations. (shrink)

Empirical advances have been made in understanding how human language, in its combinatorial complexity and unbounded expressivity, may have evolved from the communication systems present in our evolutionary ancestors. However, a number of cognitive processes and neurobiological mechanisms that support language may not have evolved specifically for communication, but rather from abilities that support perception and cognition more generally. We review recent evidence from comparative behavioural and neurobiological studies on structured sequence learning in human and nonhuman primates. These studies support (...) the notion that certain sequence learning abilities are evolutionarily conserved and engage corresponding inferior frontal brain regions across the species, regions also involved in processing language in humans. Alongside the cross-species similarities is evidence for human specialisations, illuminating the likely evolutionary pathways towards language in modern humans. We argue that cognitive abilities that were in place for animals to learn combinatorial relationships in the sensory world were available and co-opted for language in humans. (shrink)

Language is a cognitively demanding human trait, but it is also a fundamentally cooperative enterprise that rests on the motivation to share information. Great apes possess many of the cognitive prerequisites for language, but largely lack the motivation to share information. Callitrichids (including marmosets and tamarins) are highly vocal monkeys that are more distantly related to humans than great apes are, but like humans, they are cooperative breeders and all group members help raising offspring. Among primates, this rearing system is (...) correlated with proactive prosociality, which can be expressed as motivation to share information. We therefore propose that the unique coincidence of these two components in humans set the stage for language evolution: The cognitive component inherited from our great ape-like ancestors, and the motivational one added convergently as a result of cooperative breeding. We evaluate this scenario based on a review of callitrichd vocal communication and show that furthermore, they possess many of the mechanistic elements emphasized by the mirror system hypothesis of language evolution. We end by highlighting how more systematic phylogenetic comparisons will enable us to further promote our understanding of the role of cooperative breeding during language evolution. (shrink)

Despite the variety of theories suggesting how human language might have evolved, very few consider the potential role of emotions in such scenarios. The few existing theories jointly highlight that gaining control over the production of emotional communication was crucial for establishing and maintaining larger social groups. This in turn resulted in the development of more complex social emotions and the corresponding sophisticated socio-cognitive skills to understand others’ communicative behavior, providing the grounds for language to emerge. Importantly, these theories propose (...) that the ability of controlling emotional communication is a uniquely human trait, an assumption that we will challenge. By taking a comparative approach, we discuss recent findings from behavioral and neurobiological studies from our closest relatives, the non-human primates, on the extent of control over their gestural, facial and vocal signals. This demonstrates that research foci differ drastically across these modalities, which further enhances the traditional dichotomy between emotional, involuntary facial and vocal expressions in contrast to intentionally, voluntarily produced gestures. Based on this brief overview, we point to gaps of knowledge in primate communication research and suggest how investigating emotional expressions in our closest relatives might enrich the road map towards the evolution of human language. (shrink)

Many researchers consider language to be definitionally unique to humans. However, increasing evidence suggests that language emerged via a series of adaptations to neural systems supporting earlier capacities for visuomotor integration and manual action. This paper reviews comparative neuroscience evidence for the evolutionary progression of these adaptations. An outstanding question is how to mechanistically explain the emergence of new capacities from pre-existing circuitry. One possibility is that human brains may have undergone selection for greater plasticity, reducing the extent to which (...) brain organization is hard-wired and increasing the extent to which it is shaped by socially transmitted, learned behaviors. Mutations that made these new abilities easier or faster to learn would have undergone positive selection, and over time, the neural changes once associated with individual neural plasticity would tend to become heritable, innate, and fixed. Clearly, though, language is not entirely “innate;” it does not emerge without the requisite environmental input and experience. Thus, a mechanistic explanation for the evolution of language must address the inherent trade-off between the evolutionary pressure for underlying neural systems to be flexible and sensitive to environmental input vs. the tendency over time for continually adaptive behaviors to become reliably expressed in an early-emerging, canalized, less flexible manner. (shrink)

Evolutionary change occurs most often through the modification of pre-existing structures. What were the pre-existing circuits in our primate ancestors that paved the way for human language, and how did they change in the lineages leading to our present condition? Among the neural modifications that were critical for human language, there are two of special interest: The origin and evolution of the remarkably rich conceptual world that humans share to the exclusion of other primates, and the origin of neural circuitry (...) that underlies various sequential and hierarchical aspects of language, as utilized for example in syntax and word morphology. The fossil record of brain evolution and the archaeological record provide intriguing clues about these processes. (shrink)

Language and speech depend on a relatively well defined neural circuitry, located predominantly in the left hemisphere. In this article, I discuss the origin of the speech circuit in early humans, as an expansion of an auditory-vocal articulatory network that took place after the last common ancestor with the chimpanzee. I will attempt to converge this perspective with aspects of the Mirror System Hypothesis, particularly those related to the emergence of a meaningful grammar in human communication. Basically, the strengthening of (...) auditory-vocal connectivity via the arcuate fasciculus and related tracts generated an expansion of working memory capacity for vocalizations, that was key for learning complex utterances. This process was concomitant with the development of a robust interface with visual working memory, both in the dorsal and ventral streams of auditory and visual processing. This enabled the bidirectional translation of sequential codes into hierarchical visual representations, through the development of a multimodal interface between both systems. (shrink)

This paper assesses great apes’ abilities for pantomime and action imitation, two communicative abilities proposed as key contributors to language evolution. Modern great apes, the only surviving nonhuman hominids, are important living models of the communicative platform upon which language evolved. This assessment is based on 62 great ape pantomimes identified via data mining plus published reports of great ape action imitation. Most pantomimes were simple, imperative, and scaffolded by partners’ relationship and scripts; some resemble declaratives, some were sequences of (...) several inter-related elements. Imitation research consistently shows great apes perform action imitation at low fidelity, but also that action imitation may not represent a distinct process or function. Discussion focuses on how findings may advance reconstruction of the evolution of language, including what great apes may contribute to understanding ‘primitive’ forms of pantomime and imitation and how to improve their study. (shrink)

We review major developmental evidence on the continuity from action to gesture to word and sign in human children, highlighting the important role of caregivers in the development of multimodal communication. In particular, the basic issues considered here and contributing to the current debate on the origins and development of the language-ready brain are: (1) links between early actions, gestures and words and similarities in representational strategies; (2) importance of multimodal communication and the interplay between gestures and spoken words; (3) (...) interconnections between early actions, gestures and signs. The innovation of this report is in connecting these themes together to relevant findings from studies on children between 6 and 36 months of age and highlighting interesting parallels in studies on ape communicative behavior. (shrink)

This paper focuses on how human complex imitation and its developmental processes are related to the abilities for action representation, acquisition of symbols, and language. After overviewing the characteristics of imitation in chimpanzees and humans, I propose a model of imitation emphasizing how these two species differ in the ways they process visual-motor information. These differences may in turn contribute to core interspecies differences in higher-order cognitive functions, not only for bodily imitation but for action understanding through complex referential information (...) from faces, sharing symbols, and language. This ‘developmental-comparative’ approach reveals the development of species-specific intelligences, and shows what is shared and not shared between humans and other primates. In doing so, we can obtain a more complete understanding of the emergence of the ‘language-ready brain’ in relation to its biological and evolutionary foundations. (shrink)

Language- and music-readiness are demonstrated as related within comparative neuroprimatology by elaborating three hypotheses concerning music-readiness (MR): The (musicological) rhythm-first hypothesis (MR-1), the combinatoriality hypothesis (MR-2), and the socio-affect-cohesion hypothesis (MR-3). MR-1 states that rhythm precedes evolutionarily melody and tonality. MR-2 states that complex imitation and fractionation within the expanding spiral of the mirror system/complex imitation hypothesis (MS/CIH) lead to the combinatorial capacities of rhythm necessary for building up a musical lexicon and complex structures; and rhythm, in connection with repetition (...) and variation, scaffolds both musical form and content. MR-3 states that music’s main evolutionary function is to self-induce affective states in individuals to cope with distress; rhythm, in particular isochrony, provides a temporal framework to support movement synchronization, inducing shared affective states in group members, which in turn enhances group cohesion. This document reviews current behavioural and neurocognitive research relevant to the comparative neuroprimatology of music-readiness. It further proposes to extend MS/CIH through the evolution of the relationship of the language- and music-ready brain, by comparing “affective rhythm” and prosody – i.e. by comparatively approaching the language- and music-emotion link in neuroprimatology. (shrink)

This article focuses on the interweaving of constructive praxis with communication inontogenesis, inphylogenesisand in biocultural niche evolution (ecogenesis), within anEvoDevoSocioframework. I begin by discussing the nature of symbolization, its evolution from communicative signaling and its elaboration into semantic systems. I distinguish between thesymbol-readyand thelanguage-readybrain, leading to a discussion of linguistic conceptualization and itsdual groundingin organism and language system. There follows an outline account of the interpenetration in the human biocultural niche-complex ofsemiosphereandtechnosphere,mediated by the evolution of the niche of infancy. Symbolization (...) (the foundation of the semiosphere) is by definition normative; the normative character of the technosphere is demonstrated by the interrelations in human development between affordance, action schema and canonical functional object schema. A model of the neuro-computational implementation of dual grounding is proposed. (shrink)

In this paper, we complement proximate or ‘how’ explanations for the origins of language, broadening our perspective to include fitness-consequences explanations, i.e. ultimate, or ‘why’ explanations. We identify theplatform of trustas a fundamental prerequisite for the development of a language-like system of symbolic communication. The platform of trust is a social niche in which cheap but honest communication with non-kin is possible, because messages tend to be trusted as a default. We briefly consider the place of the platform of trust (...) on the road map as laid out in the Mirror System Hypothesis. We then turn to recent research on turn-taking in primates, which has been proposed as a precursor of the cooperative structuring of conversation in humans. We suggest, instead, that human turn-taking, in its full richness that makes it an interesting explanatory target, may only appear in a communicative system that is already founded on a community-wide, cooperative platform of trust. (shrink)