In the target article, Ackermann et al. contend that speech has emerged as a major evolutionary advantage in hominin ancestors as a result of a refinement in the projections from the motor cortex to the brainstem nuclei responsible for the control of laryngeal muscles as well as the further development of vocalization-specific cortico-basal ganglia circuitries driven by certain mutations in the FOXP2 gene which were unique to humans.
Complex adaptive system (CAS) analysis has emerged as a powerful research approach that has been successfully used to study the basic mechanisms underlying the evolution of dynamical systems composed of multiple agents interacting through complex and interdependent networks. As a broad and general theoretical tool, CAS analysis has been employed in a variety of research fields in both biological and social sciences in order to unveil the common general principles responsible for the evolution of apparently unrelated complex systems, such as global macroeconomics (Gintis Reference Gintis2006), the stock market (Mauboussin Reference Mauboussin2002), geopolitical organizations (Braman Reference Braman and Braman2004), the cyberspace (Phister Reference Phister2010), natural ecosystems (Levin Reference Levin1998), the immune system (Grilo et al. Reference Grilo, Caetano, Rosa, Roy, Köppen, Ovaska, Furuhashi and Hoffmann2002), the human brain (Gomez Portillo & Gleiser Reference Gomez Portillo and Gleiser2009), and intracellular signaling networks (Schwab & Pienta Reference Schwab and Pienta1997).
Recently it has been suggested that, taking into account the dynamic nature of grammar and semantics' evolution throughout the centuries, language should be considered a typical example of a complex adaptive system (Ellis Reference Ellis2009). More importantly, the emergence of the cognitive apparatus responsible for the processing of acoustic communication can be regarded as a unique breakthrough within biological complex adaptive systems, as it fostered the development of new signaling networks not only among different individuals, but also within the subsystems operating inside each specific agent (Pinker Reference Pinker2010). By enabling dynamical inter-individual interactions through fast and instantaneous feedback loops, the emergence of speech granted the biological systems harboring such a new cognitive resource an enormous evolutionary advantage not only from the individual standpoint, but also from the perspective of further development of the whole species through social collaboration. Ultimately the combination of such new signaling networks built upon oral communication and language gave rise to more complex and general social elements, which, in turn, began to play a central role in the very interactions among such individuals through new types of information exchange pathways such as advertisement, mass communication vehicles, and, more recently, social media (Fitch Reference Fitch2006).
By exploring the underlying brain structures involved in the phylogenetic emergence of speech, the target article demonstrates how the use of words, as standardized vocal utterances filled with specific meaning (or, as Ackermann et al. call them, phonetic-linguistic categories), represents a unique cognitive resource of the human species. In a simple manner, speech can be understood as a voluntary pattern of vocalization common to a social community which has definite connotations and which is carefully manipulated at each individual communication event for the transferring of specific information, intentions, and abstract ideas. As discussed by the authors, despite the fact that close primates may demonstrate elaborated oral-motor capabilities and possess an extensive vocal repertoire, they fail in producing a pattern of vocal communication that resembles speech. As properly pointed by Ackermann et al., nonhuman primate oral communication would be much more similar to other nonverbal affective forms of human vocal expressions (such as laughing, crying, or moaning) than to any type of organized and standardized pattern of vocalization that might possibly deserve the status of language. Based on such considerations, Ackermann et al. argue that a unique state of development of the neurophysiological networks responsible for coupling intentional planning and the refined coordination between the several motor elements involved in phonation (such as the tongue, laryngeal, jaw and facial muscles), ultimately enabled the human race to cross the critical edge that separates the crude vocalization patterns observed in other primates from human speech and language. In this sense, it could be said that, from the phylogenetic standpoint of brain evolution, the observed advancements in the neuroanatomical areas responsible for acoustic communication mentioned in the target article (such as the cortico-brainstem connections and the FOXP2 gene-induced new cortico-basal projections) fostered the further development of the primary cortical areas related to language emission (Broca's area, which is localized in the left inferior frontal gyrus of the dominant hemisphere – Brodmann's areas 44 and 45) and language comprehension (Wernicke's area, which is localized in the posterior section of the superior temporal gyrus – Brodmann's area 22) as well as of the white matter connection tracts and the accessory heteromodal association areas involved in the generation and processing of different speech features such as prosody, melody, rhythm, pitch, and syntax (Rauschecker Reference Rauschecker2012).
Such refinement in the brain networks responsible for the production and processing of speech in conjunction with advances in other brain regions which enabled the emergence of more complex non-pictographic forms of written language (i.e. systems which provided symbolic representations for the phonemes and words that became established in the oral culture throughout early human history) were also a decisive factor for the development of other higher cognitive functions which ended up achieving a uniquely sophisticated status in humans, such as semantic memory, abstraction, future anticipation and planning, and mathematical reasoning (Aboitiz et al. Reference Aboitiz, García, Bosman and Brunetti2006).
In summary, the specific pattern observed in the evolutionary development of speech highlighted in the target article (which involves one breakthrough change leading to the percolation of the whole system and the emergence of new unpredictable attributes) represents a typical feature of complex adaptive systems. In fact, in such types of self-adapting and dynamical systems, it has already been demonstrated that a significant improvement in the signaling flow among agents (such as that proportioned by the development of speech and language) constitutes one of the most powerful triggering events for the emergence of new complex behaviors, very often leading to a complete reformulation of the boundaries and hierarchical structures within the system (Holland Reference Holland2012). As an academic masterpiece on the issue, Ackermann and colleagues' comprehensive phylogenetic analysis of the brain structures responsible for speech in humans and nonhumans primates provides further evidence of the essential role that speech and language, as breakthrough signaling resources, have played in the evolutionary development of human cognition viewed from the standpoint of complex adaptive system analysis.
In the target article, Ackermann et al. contend that speech has emerged as a major evolutionary advantage in hominin ancestors as a result of a refinement in the projections from the motor cortex to the brainstem nuclei responsible for the control of laryngeal muscles as well as the further development of vocalization-specific cortico-basal ganglia circuitries driven by certain mutations in the FOXP2 gene which were unique to humans.
Complex adaptive system (CAS) analysis has emerged as a powerful research approach that has been successfully used to study the basic mechanisms underlying the evolution of dynamical systems composed of multiple agents interacting through complex and interdependent networks. As a broad and general theoretical tool, CAS analysis has been employed in a variety of research fields in both biological and social sciences in order to unveil the common general principles responsible for the evolution of apparently unrelated complex systems, such as global macroeconomics (Gintis Reference Gintis2006), the stock market (Mauboussin Reference Mauboussin2002), geopolitical organizations (Braman Reference Braman and Braman2004), the cyberspace (Phister Reference Phister2010), natural ecosystems (Levin Reference Levin1998), the immune system (Grilo et al. Reference Grilo, Caetano, Rosa, Roy, Köppen, Ovaska, Furuhashi and Hoffmann2002), the human brain (Gomez Portillo & Gleiser Reference Gomez Portillo and Gleiser2009), and intracellular signaling networks (Schwab & Pienta Reference Schwab and Pienta1997).
Recently it has been suggested that, taking into account the dynamic nature of grammar and semantics' evolution throughout the centuries, language should be considered a typical example of a complex adaptive system (Ellis Reference Ellis2009). More importantly, the emergence of the cognitive apparatus responsible for the processing of acoustic communication can be regarded as a unique breakthrough within biological complex adaptive systems, as it fostered the development of new signaling networks not only among different individuals, but also within the subsystems operating inside each specific agent (Pinker Reference Pinker2010). By enabling dynamical inter-individual interactions through fast and instantaneous feedback loops, the emergence of speech granted the biological systems harboring such a new cognitive resource an enormous evolutionary advantage not only from the individual standpoint, but also from the perspective of further development of the whole species through social collaboration. Ultimately the combination of such new signaling networks built upon oral communication and language gave rise to more complex and general social elements, which, in turn, began to play a central role in the very interactions among such individuals through new types of information exchange pathways such as advertisement, mass communication vehicles, and, more recently, social media (Fitch Reference Fitch2006).
By exploring the underlying brain structures involved in the phylogenetic emergence of speech, the target article demonstrates how the use of words, as standardized vocal utterances filled with specific meaning (or, as Ackermann et al. call them, phonetic-linguistic categories), represents a unique cognitive resource of the human species. In a simple manner, speech can be understood as a voluntary pattern of vocalization common to a social community which has definite connotations and which is carefully manipulated at each individual communication event for the transferring of specific information, intentions, and abstract ideas. As discussed by the authors, despite the fact that close primates may demonstrate elaborated oral-motor capabilities and possess an extensive vocal repertoire, they fail in producing a pattern of vocal communication that resembles speech. As properly pointed by Ackermann et al., nonhuman primate oral communication would be much more similar to other nonverbal affective forms of human vocal expressions (such as laughing, crying, or moaning) than to any type of organized and standardized pattern of vocalization that might possibly deserve the status of language. Based on such considerations, Ackermann et al. argue that a unique state of development of the neurophysiological networks responsible for coupling intentional planning and the refined coordination between the several motor elements involved in phonation (such as the tongue, laryngeal, jaw and facial muscles), ultimately enabled the human race to cross the critical edge that separates the crude vocalization patterns observed in other primates from human speech and language. In this sense, it could be said that, from the phylogenetic standpoint of brain evolution, the observed advancements in the neuroanatomical areas responsible for acoustic communication mentioned in the target article (such as the cortico-brainstem connections and the FOXP2 gene-induced new cortico-basal projections) fostered the further development of the primary cortical areas related to language emission (Broca's area, which is localized in the left inferior frontal gyrus of the dominant hemisphere – Brodmann's areas 44 and 45) and language comprehension (Wernicke's area, which is localized in the posterior section of the superior temporal gyrus – Brodmann's area 22) as well as of the white matter connection tracts and the accessory heteromodal association areas involved in the generation and processing of different speech features such as prosody, melody, rhythm, pitch, and syntax (Rauschecker Reference Rauschecker2012).
Such refinement in the brain networks responsible for the production and processing of speech in conjunction with advances in other brain regions which enabled the emergence of more complex non-pictographic forms of written language (i.e. systems which provided symbolic representations for the phonemes and words that became established in the oral culture throughout early human history) were also a decisive factor for the development of other higher cognitive functions which ended up achieving a uniquely sophisticated status in humans, such as semantic memory, abstraction, future anticipation and planning, and mathematical reasoning (Aboitiz et al. Reference Aboitiz, García, Bosman and Brunetti2006).
In summary, the specific pattern observed in the evolutionary development of speech highlighted in the target article (which involves one breakthrough change leading to the percolation of the whole system and the emergence of new unpredictable attributes) represents a typical feature of complex adaptive systems. In fact, in such types of self-adapting and dynamical systems, it has already been demonstrated that a significant improvement in the signaling flow among agents (such as that proportioned by the development of speech and language) constitutes one of the most powerful triggering events for the emergence of new complex behaviors, very often leading to a complete reformulation of the boundaries and hierarchical structures within the system (Holland Reference Holland2012). As an academic masterpiece on the issue, Ackermann and colleagues' comprehensive phylogenetic analysis of the brain structures responsible for speech in humans and nonhumans primates provides further evidence of the essential role that speech and language, as breakthrough signaling resources, have played in the evolutionary development of human cognition viewed from the standpoint of complex adaptive system analysis.