The invasion of language: emergence, change and death

Research into the emergence and evolution of human language has received unprecedented attention during the past 15 years. Efforts to better understand the processes of language emergence and evolution have proceeded in two main directions: from the top-down (linguists) and from the bottom-up (cognitive scientists). Language can be viewed as an invading process that has had profound impact on the human phenotype at all levels, from the structure of the brain to modes of cultural interaction. In our view, the most effective way to form a connection between the two efforts (essential if theories for language evolution are to reflect the constraints imposed on language by the brain) lies in computational modelling, an approach that enables numerous hypotheses to be explored and tested against objective criteria and which suggest productive paths for empirical researchers to then follow. Here, with the aim of promoting the cross-fertilization of ideas across disciplines, we review some of the recent research that has made use of computational methods in three principal areas of research into language evolution: language emergence, language change, and language death.     

Language from a biological perspective

The faculty of language is unique to the human species. This implies that there are human-specific biological changes that lie at the basis of human language. However, it is not clear what the nature of such changes are, and how they could be shaped by evolution. In this paper, emphasis is laid on describing language in a Chomskyan manner, as a mental object. This serves as a standpoint to speculate about the biological basis of the emergence and evolution of language.     

Two organizing principles of vocal production: Implications for nonhuman and human primates

Vocal communication in nonhuman primates receives considerable research attention, with many investigators arguing for similarities between this calling and speech in humans. Data from development and neural organization show a central role of affect in monkey and ape sounds, however, suggesting that their calls are homologous to spontaneous human emotional vocalizations while having little relation to spoken language. Based on this evidence, we propose two principles that can be useful in evaluating the many and disparate empirical findings that bear on the nature of vocal production in nonhuman and human primates. One principle distinguishes production-first from reception-first vocal development, referring to the markedly different role of auditory-motor experience in each case. The second highlights a phenomenon dubbed dual neural pathways, specifically that when a species with an existing vocal system evolves a new functionally distinct vocalization capability, it occurs through emergence of a second parallel neural pathway rather than through expansion of the extant circuitry. With these principles as a backdrop, we review evidence of acoustic modification of calling associated with background noise, conditioning effects, audience composition, and vocal convergence and divergence in nonhuman primates. Although each kind of evidence has been interpreted to show flexible cognitively mediated control over vocal production, we suggest that most are more consistent with affectively grounded mechanisms. The lone exception is production of simple, novel sounds in great apes, which is argued to reveal at least some degree of volitional vocal control. If also present in early hominins, the cortically based circuitry surmised to be associated with these rudimentary capabilities likely also provided the substrate for later emergence of the neural pathway allowing volitional production in modern humans.     

From animal communication to the human language and cognition: evolution or revolution?

The paper discusses the problem of language and cognitive specificity in humans as compared to other species. The main hypotheses of human evolution and the emergence of language seem to be well researched on genetic basis of higher functions. Cognitive abilities of other animals and their communication signals and the main views on basic principles of brain underlying these functions are described.     

Emerging viral infections in a rapidly changing world

Emerging viral infections in both humans and animals have been reported with increased frequency in recent years. Recent advances have been made in our knowledge of some of these, including severe acute respiratory syndrome-associated coronavirus, influenza A virus, human metapneumovirus, West Nile virus and Ebola virus. Research efforts to mitigate their effects have concentrated on improved surveillance and diagnostic capabilities, as well as on the development of vaccines and antiviral agents. More attention needs to be given to the identification of the underlying causes for the emergence of infectious diseases, which are often related to anthropogenic social and environmental changes. Addressing these factors might help to decrease the rate of emergence of infectious diseases and allow the transition to a more sustainable society.     

Playing with language,creating complexity: Has play contributed to the evolution of complex language?

We argue that enhanced play may have contributed to the emergence of complex language systems in modern humans (Homo sapiens). To support this idea, we first discuss evidence for an expansion of playing behavior connected to the extended childhood of modern human children, and the potential of this period for the transmission of complex cultural traits, including language. We then link two of the most important functions of play—exploration and innovation—to the potential for cumulative cultural evolution in general and for the emergence of complex language in particular. If correct, the shorter childhood of Neanderthals—involving restrictions on time to experiment and innovate—may have restricted their language (and other symbolic) system/s. Consequently, fully investigating the role that play may have had in the transmission of language and the development of symbolic cultures in both modern humans and Neanderthals provides a new avenue of research for Paleolithic archaeology and related disciplines.     

The origin of human multi-modal communication

One reason for the apparent gulf between animal and human communication systems is that the focus has been on the presence or the absence of language as a complex expressive system built on speech. But language normally occurs embedded within an interactional exchange of multi-modal signals. If this larger perspective takes central focus, then it becomes apparent that human communication has a layered structure, where the layers may be plausibly assigned different phylogenetic and evolutionary origins—especially in the light of recent thoughts on the emergence of voluntary breathing and spoken language. This perspective helps us to appreciate the different roles that the different modalities play in human communication, as well as how they function as one integrated system despite their different roles and origins. It also offers possibilities for reconciling the ‘gesture-first hypothesis’ with that of gesture and speech having evolved together, hand in hand—or hand in mouth, rather—as one system.     

Evolutionary biology of language

Language is the most important evolutionary invention of the last few million years. It was an adaptation that helped our species to exchange information, make plans, express new ideas and totally change the appearance of the planet. How human language evolved from animal communication is one of the most challenging questions for evolutionary biology The aim of this paper is to outline the major principles that guided language evolution in terms of mathematical models of evolutionary dynamics and game theory. I will discuss how natural selection can lead to the emergence of arbitrary signs, the formation of words and syntactic communication.     

A neuropsychological perspective on the link between language and praxis in modern humans

Hypotheses about the emergence of human cognitive abilities postulate strong evolutionary links between language and praxis, including the possibility that language was originally gestural. The present review considers functional and neuroanatomical links between language and praxis in brain-damaged patients with aphasia and/or apraxia. The neural systems supporting these functions are predominantly located in the left hemisphere. There are many parallels between action and language for recognition, imitation and gestural communication suggesting that they rely partially on large, common networks, differentially recruited depending on the nature of the task. However, this relationship is not unequivocal and the production and understanding of gestural communication are dependent on the context in apraxic patients and remains to be clarified in aphasic patients. The phonological, semantic and syntactic levels of language seem to share some common cognitive resources with the praxic system. In conclusion, neuropsychological observations do not allow support or rejection of the hypothesis that gestural communication may have constituted an evolutionary link between tool use and language. Rather they suggest that the complexity of human behaviour is based on large interconnected networks and on the evolution of specific properties within strategic areas of the left cerebral hemisphere.     

Adaptive Communication: Languages with More Non-Native Speakers Tend to Have Fewer Word Forms

Explaining the diversity of languages across the world is one of the central aims of typological, historical, and evolutionary linguistics. We consider the effect of language contact-the number of non-native speakers a language has-on the way languages change and evolve. By analysing hundreds of languages within and across language families, regions, and text types, we show that languages with greater levels of contact typically employ fewer word forms to encode the same information content (a property we refer to as lexical diversity). Based on three types of statistical analyses, we demonstrate that this variance can in part be explained by the impact of non-native speakers on information encoding strategies. Finally, we argue that languages are information encoding systems shaped by the varying needs of their speakers. Language evolution and change should be modeled as the co-evolution of multiple intertwined adaptive systems: On one hand, the structure of human societies and human learning capabilities, and on the other, the structure of language.     

Increased breathing control: Another factor in the evolution of human language

Investigation into the evolution of human language has involved evidence of many different kinds and approaches from many different disciplines. For full modern language, humans must have evolved a range of physical abilities for the production of our complex speech sounds, as well as sophisticated cognitive abilities. Human speech involves free‐flowing, intricately varied, rapid sound sequences suitable for the fast transfer of complex, highly flexible communication. Some aspects of human speech, such as our ability to manipulate the vocal tract to produce a wide range of different types of sounds that form vowels and consonants, have attracted considerable attention from those interested in the evolution of language. 1 , 2 However, one very important contributory skill, the human ability to attain very fine control of breathing during speech, has been neglected. Here we present evidence of the importance of breathing control to human speech, as well as evidence that our capabilities greatly exceed those of nonhuman primates. Human speech breathing demands fine neurological control of the respiratory muscles, integrated with cognitive processes and other factors. Evidence from comparison of the vertebral canals of fossil hominids and those of extant primates suggests that a major increase in thoracic innervation evolved in later hominid evolution, providing enhanced breathing control. If that is so, then earlier hominids would have had quite restricted speech patterns, whereas more recent hominids, with human‐like breath control abilities, would have been capable of faster, more varied speech sequences.     

Neural basis of mathematical cognition

The human brain has remarkable capabilities for encoding and manipulating information about quantities. Understanding how the brain carries out such number and quantity processing is a problem not just for those interested in numerical cognition: it raises important questions that are relevant to understanding development, action, vision, language, executive function and cortical organisation. It is also a clear case of research into a core human psychological function having indisputable everyday relevance; hence the emphasis in early education on numeracy and later on mathematics.     

The origins of gestures and language: history,current advances and proposed theories

Investigating in depth the mechanisms underlying human and non‐human primate intentional communication systems (involving gestures, vocalisations, facial expressions and eye behaviours) can shed light on the evolutionary roots of language. Reports on non‐human primates, particularly great apes, suggest that gestural communication would have been a crucial prerequisite for the emergence of language, mainly based on the evidence of large communication repertoires and their associated multifaceted nature of intentionality that are key properties of language. Such research fuels important debates on the origins of gestures and language. We review here three non‐mutually exclusive processes that can explain mainly great apes' gestural acquisition and development: phylogenetic ritualisation, ontogenetic ritualisation, and learning via social negotiation. We hypothesise the following scenario for the evolutionary origins of gestures: gestures would have appeared gradually through evolution via signal ritualisation following the principle of derived activities, with the key involvement of emotional expression and processing. The increasing level of complexity of socioecological lifestyles and associated daily manipulative activities might then have enabled the acquisition and development of different interactional strategies throughout the life cycle. Many studies support a multimodal origin of language. However, we stress that the origins of language are not only multimodal, but more broadly multicausal. We propose a multicausal theory of language origins which better explains current findings. It postulates that primates' communicative signalling is a complex trait continually shaped by a cost–benefit trade‐off of signal production and processing of interactants in relation to four closely interlinked categories of evolutionary and life cycle factors: species, individual and context‐related characteristics as well as behaviour and its characteristics. We conclude by suggesting directions for future research to improve our understanding of the evolutionary roots of gestures and language.     

The function and mechanism of vocal accommodation in humans and other primates

The study of non‐human animals, in particular primates, can provide essential insights into language evolution. A critical element of language is vocal production learning, i.e. learning how to produce calls. In contrast to other lineages such as songbirds, vocal production learning of completely new signals is strikingly rare in non‐human primates. An increasing body of research, however, suggests that various species of non‐human primates engage in vocal accommodation and adjust the structure of their calls in response to environmental noise or conspecific vocalizations. To date it is unclear what role vocal accommodation may have played in language evolution, in particular because it summarizes a variety of heterogeneous phenomena which are potentially achieved by different mechanisms. In contrast to non‐human primates, accommodation research in humans has a long tradition in psychology and linguistics. Based on theoretical models from these research traditions, we provide a new framework which allows comparing instances of accommodation across species, and studying them according to their underlying mechanism and ultimate biological function. We found that at the mechanistic level, many cases of accommodation can be explained with an automatic perception–production link, but some instances arguably require higher levels of vocal control. Functionally, both human and non‐human primates use social accommodation to signal social closeness or social distance to a partner or social group. Together, this indicates that not only some vocal control, but also the communicative function of vocal accommodation to signal social closeness and distance must have evolved prior to the emergence of language, rather than being the result of it. Vocal accommodation as found in other primates has thus endowed our ancestors with pre‐adaptations that may have paved the way for language evolution.     

Learning bias, cultural evolution of language, and the biological evolution of the language faculty

The biases of individual language learners act to determine the learnability and cultural stability of languages: learners come to the language learning task with biases which make certain linguistic systems easier to acquire than others. These biases are repeatedly applied during the process of language transmission, and consequently should effect the types of languages we see in human populations. Understanding the cultural evolutionary consequences of particular learning biases is therefore central to understanding the link between language learning in individuals and language universals, common structural properties shared by all the world’s languages. This paper reviews a range of models and experimental studies which show that weak biases in individual learners can have strong effects on the structure of socially learned systems such as language, suggesting that strong universal tendencies in language structure do not require us to postulate strong underlying biases or constraints on language learning. Furthermore, understanding the relationship between learner biases and language design has implications for theories of the evolution of those learning biases: models of gene-culture coevolution suggest that, in situations where a cultural dynamic mediates between properties of individual learners and properties of language in this way, biological evolution is unlikely to lead to the emergence of strong constraints on learning.     

On emergence, agency, and organization

Ultimately we will only understand biological agency when we have developed a theory of the organization of biological processes, and science is still a long way from attaining that goal. It may be possible nonetheless to develop a list of necessary conditions for the emergence of minimal biological agency. The authors offer a model of molecular autonomous agents which meets the five minimal physical conditions that are necessary (and, we believe, conjointly sufficient) for applying agential language in biology: autocatalytic reproduction; work cycles; boundaries for reproducing individuals; self-propagating work and constraint construction; and choice and action that have evolved to respond to food or poison. When combined with the arguments from preadaptation and multiple realizability, the existence of these agents is sufficient to establish ontological emergence as against what one might call Weinbergian reductionism. Minimal biological agents are emphatically not conscious agents, and accepting their existence does not commit one to any robust theory of human agency. Nor is there anything mystical, dualistic, or non-empirical about the emergence of agency in the biosphere. Hence the emergence of molecular autonomous agents, and indeed ontological emergence in general, is not a negation of or limitation on careful biological study but simply one of its implications.     

Determining the Presence of Superantigens in Coagulase Negative Staphylococci from Humans

Superantigens (SAgs) are important virulence factors in S. aureus. Recent studies identified their presence in animal coagulase-negative staphylococci (CNS). The emergence of human-associated SAg⁺ CNS would mark a prodigious shift in virulence capabilities. We examined CNS isolates from healthy human nares and diseased individuals, and determined that no known SAgs were present.     

Neural correlates of Early Stone Age toolmaking: technology, language and cognition in human evolution

Archaeological and palaeontological evidence from the Early Stone Age (ESA) documents parallel trends of brain expansion and technological elaboration in human evolution over a period of more than 2Myr. However, the relationship between these defining trends remains controversial and poorly understood. Here, we present results from a positron emission tomography study of functional brain activation during experimental ESA (Oldowan and Acheulean) toolmaking by expert subjects. Together with a previous study of Oldowan toolmaking by novices, these results document increased demands for effective visuomotor coordination and hierarchical action organization in more advanced toolmaking. This includes an increased activation of ventral premotor and inferior parietal elements of the parietofrontal praxis circuits in both the hemispheres and of the right hemisphere homologue of Broca's area. The observed patterns of activation and of overlap with language circuits suggest that toolmaking and language share a basis in more general human capacities for complex, goal-directed action. The results are consistent with coevolutionary hypotheses linking the emergence of language, toolmaking, population-level functional lateralization and association cortex expansion in human evolution.     

Evolution of language: attempt at synthesis

There are at least three traits that distinguish modern Homo sapiens from his closest relatives: bipedal locomotion, the unusual size of his brain and the ability to use symbolic language. To this day the emergence and evolution of these traits have not been explained sufficiently. New research in anthropology, linguistics, cognitive science and other disciplines shows, that the evolution of the human language faculty is a complex field that was influenced by a wide variety of factors. This paper tries to show the width of these factors and to work out the demands that are to be met by a theory of language evolution. After the introduction, in Section 2 the evolutionary principles and their role in the evolution of symbolic communication will be reviewed. Section 3 gives an overview of the results and controversies of brain evolution research, while Section 4 introduces our current knowledge of the neuronal basis of language. In Section 5 the controversies that had the greatest impact on the field and development of ways to solve them are reviewed before Section 6 summarizes the most important preadaptations for the evolving language faculty.