The evolution of the capacity for language: the ecological context and adaptive value of a process of cognitive hijacking

Abstract

Language plays a pivotal role in the evolution of human culture, yet the evolution of the capacity for language-uniquely within the hominin lineage-remains little understood. Bringing together insights from cognitive psychology, neuroscience, archaeology and behavioural ecology, we hypothesize that this singular occurrence was triggered by exaptation, or 'hijacking', of existing cognitive mechanisms related to sequential processing and motor execution. Observed coupling of the communication system with circuits related to complex action planning and control supports this proposition, but the prehistoric ecological contexts in which this coupling may have occurred and its adaptive value remain elusive. Evolutionary reasoning rules out most existing hypotheses regarding the ecological context of language evolution, which focus on ultimate explanations and ignore proximate mechanisms. Coupling of communication and motor systems, although possible in a short period on evolutionary timescales, required a multi-stepped adaptive process, involving multiple genes and gene networks. We suggest that the behavioural context that exerted the selective pressure to drive these sequential adaptations had to be one in which each of the systems undergoing coupling was necessary or highly beneficial, as well as frequent and recurring over evolutionary time. One such context could have been the teaching of tool production or tool use. In the present study, we propose the Cognitive Coupling hypothesis, which brings together these insights and outlines a unifying theory for the evolution of the capacity for language.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

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

“…Moreover, both play and language share a computational/motor dimension: playing behavior entails the planning and execution of motor sequences, while sentence construction involves the arrangement of symbolic units (words) following a set of rules (grammar). Over the course of development, these precursors to play and language grow into complex abilities: the motor control required for single object reach subsequently drives the motor control that underpins more complex playing and verbal behavior, hence the hypothesis that the sequencing ability involved in tool‐making might have constituted a precursor of the ability to produce complex grammar (the “technological hypothesis”) …”

“…Over the course of development, these precursors to play and language grow into complex abilities: the motor control required for single object reach subsequently drives the motor control that underpins more complex playing and verbal behavior, 77 hence the hypothesis that the sequencing ability involved in tool-making might have constituted a precursor of the ability to produce complex grammar (the "technological hypothesis"). 7,78,79 In addition to sharing common origins, language and play can also be mutually supportive behaviors. [80][81][82] While functional play only correlates with expressive language, symbolic play, in which children make substitutions and transfer between objects and actions, significantly correlates with both expressive and receptive language.…”

Integrative studies of cultural evolution: crossing disciplinary boundaries to produce new insights

“…Studies at this level take theoretical and empirical approaches to population-level cultural dynamics, including patterns of the accumulation and loss of cultural traits in a population and the interaction between populations [10][11][12][13][14][15][16][17][18][19]. Yet other studies take an even higher-level approach, focusing on species: for example, evolutionary questions surrounding differences in social learning mechanisms, cultural niche construction, gene-culture coevolution, and the capacity for language in humans and vocal learning in birds [3,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Bridging cultural gaps: interdisciplinary studies in human cultural evolution

“…The aim of this issue is to advance interdisciplinary discussion of the roles that culture plays in shaping the course of human evolution, exploring the mechanisms of cultural evolution from their cognitive underpinnings in individuals, through the behavioural ecology of learning from others, to the dynamics of transmission at the level of individuals and populations. The articles in this issue bring insights from disparate disciplines to bear on major questions in cultural evolution [1][2][3][4][5][6][7][8][9][10][11] and suggest broad-scale ways in which the study of cultural evolution can be synthesized with other disciplines [12][13][14].…”

“…Applying this approach to a topic at the heart of cultural evolution, she outlines the possible cognitive processes that may underlie cultural transmission, asking whether a Darwinian view of selection dynamics is a correct description of these processes. Kolodny & Edelman [2] combine a cognitive approach with the thought paradigm of evolutionary biology to tackle the question of the evolution of the capacity for language. The authors bring together ideas and insights from anthropology, archaeology and behavioural ecology to suggest an explicit scenario for the ecological context in which language may have evolved, and they build on current knowledge of neural anatomy and function to outline a computational level model of the underpinnings of this adaptation.…”