Opinion Language Evolution: A Changing Perspective

Religion and philosophy have traditionally viewed language as a unique and sudden gift to humans, primarily for thought, with communication as a secondary function. This contrasts with the theory of evolution, which suggests gradual development of complex structures.

Is Language Uniquely Human?

The Old Testament suggests language was given to Adam and was once universal. God then confused languages at the Tower of Babel. Similarly, Noam Chomsky proposes language was bestowed on a single individual, "Prometheus," around 100,000 years ago, after Homo sapiens emerged. This timing aligns with archaeological findings showing an explosion of art and technology around that time, followed by H. sapiens' dispersal from Africa, replacing other hominins. Artifacts from this period include cave art, musical instruments, and record-keeping notations. This surge is termed the ‘human revolution’ or ‘great leap forward,’ considered a major transition in evolution. Paleoanthropologist Ian Tattersall argues that modern Homo sapiens appeared too rapidly for natural selection to account for.

The Evolutionary Challenge

Such views oppose evolutionary theory. Charles Darwin stated his theory would fail if a complex organ couldn't have formed through numerous, slight modifications. Chomsky considers language an organ on par with the digestive and immune systems. Given the complexity of language and the fact that its rules are still not fully understood after 60 years of Chomskian linguistics, its sudden emergence contradicts Darwinian theory.

Evolutionary theory has evolved through the Modern Synthesis and the Extended Evolutionary Synthesis, which incorporate genetics, embryology, and population thinking, allowing for more rapid change than random mutation selection. Pinker and Bloom suggest language could be a 'spandrel' or byproduct of the brain's computational capacity. However, they believe natural selection shaped language within the orthodox neo-Darwinian theory. Gould and Eldredge proposed ‘punctuated evolution,’ where evolution occurs in spurts, but not due to ecological catastrophe or sudden genetic change. Chomsky appeals to evo-devo, suggesting complex changes arise from mutations in regulatory genes that control development timing, but these mutations don't add complexity. Niche construction, where organisms modify their environments, potentially accelerated change during the Pleistocene and the emergence of the ‘cognitive niche,’ but this implies a 2-million-year gestation period, not a sudden change.

Language and Thought

Advocates for the sudden emergence of language link it to a change in thought. Tattersall notes that symbolic thought indications appeared around 100,000 years ago. Chomsky considers 'internal language' (I-language) the basis of human symbolic thought, with communication as a byproduct. 'Externalization' forms diverse languages. Universal grammar underlies I-language and is common to all humans. Chomsky's Minimalist Program is a recent account, with ‘unbounded Merge’ as the main ingredient. If language is communication, not thought, precursors in nonhuman animals can be considered, rather than a sudden appearance in H. sapiens. Language then becomes a tool for sharing thoughts and experiences. This view 'turns the Chomsky proposal on its head.' The ‘great leap forward’ may be due to an enhanced capacity to share knowledge and experience rather than thought itself.

Thought isn't entirely independent of language. Many thoughts and knowledge come from others. Thoughts, whether personal or communicated, differ from the language expressing them. We struggle to find words for thoughts or individuals we can envisage. Thought isn't tied to a specific language; translation maintains thought despite different words. Retelling stories involves different words. As a source of knowledge, language creates a ratchet effect, with knowledge building over time and spreading, enabling specializations. Language may have influenced the human revolution through its power of communication rather than a change in the innate structure of thought.

Expressive language, designed for communication, is shaped by thought structure. The nature and structure of thought have a long, gradual evolutionary history. Possible precursors of language include tool manufacture, navigation, reciprocal altruism, and social understanding. Mental capacities critical to recursive, generative language, may obviate a mechanism unique to language or our species.

Mental Time Travel

'Displacement,' a design feature of language, references events at other times and places and relies on the ability to imagine such events. Mental time travel may have a long evolutionary history, with evidence from species like scrub jays, rats, and chimpanzees. Neuroscience shows the hippocampus activates when people remember past episodes, imagine future ones, or imagine fictitious ones. In rats, 'place cells' in the hippocampus record spatial locations, tracing trajectories. These trajectories can be replays, reversals, or novel paths, some anticipating future trajectories. Moser, Rowland, and Moser suggest the replay phenomenon supports mental time travel. Mental travels may be common to animals that move in space. In humans, the hippocampus involves language. Hippocampal activity in rats has language-like properties, influenced by the entorhinal cortex in a modular fashion. Combinations of modules can result in thousands of combinations, similar to an alphabet. Spatial imagination, like language, is generative. The spatial scale zooms out as recording shifts from the rearward to the forward end of the hippocampus, mirrored in humans processing narratives. Generative grammar relies on spatiotemporal imagination rather than properties unique to language. The zooming property implies recursion, with spatial maps nested in maps at larger scales. Chomsky’s Minimalist Program and Merge may apply to sensorimotor actions. Our thoughts may be grounded in spatial metaphor. Universal grammar may reside in the common experience of the spatiotemporal world rather than the innate structure of language.

Theory of Mind

We travel mentally into the minds of others. Theory of mind underlies storytelling. Theory of mind is required for language because the speaker and listener must know what is in each other’s minds. Language is underdetermined. Words have multiple meanings based on context. The English word ‘set’ has 105 different meanings. Whether nonhuman species possess theory of mind has been much disputed. Some studies suggest chimpanzees understand goals, intentions, perceptions, and knowledge but not beliefs or desires. Recent studies show great apes anticipate where a human agent will falsely believe an object has been hidden, passing the false-belief test. Rhesus monkeys may be capable of spontaneous metacognition. A neural network for mental orientation in ‘space, time, and person’ includes widespread regions in the frontal, parietal, and temporal cortices. This network overlaps with the ‘default mode network.’ Homologous networks have been identified in monkeys and rats, suggesting evolutionary continuity. Mental thinking may be less complex in rats and monkeys than in humans. Darwin said: ‘The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind’. Comparative research increasingly concludes that some nonhuman animals are capable of more ‘advanced’ cognition than previously thought, suggesting evolutionary continuity rather than a sudden shift in cognition. Mental excursions may be more comprehensive and sophisticated in humans due to language, which feeds our mental travels through storytelling and our minds through the exchange of knowledge. Their origins may go well back in our evolutionary history.

The Communicative Aspect

Our ability to communicate our thoughts, rather than our thoughts themselves, distinguishes us from other species. Great apes and dogs can understand and respond to spoken requests, implying symbolic understanding but a lack of productive language. Great apes may communicate more effectively through bodily movement and gesture. Pressure to develop flexible output systems grew during the Pleistocene when hominins were forced into open territory. The initial impetus may have come from sharing episodic events, information about territory, danger, food sources, tool making, and individual abilities. Brain size increased incrementally over 2 million years, likely due to grammatical language and increased knowledge.

Concluding Remarks: Is Rapprochement Possible?

The divide over language evolution may be softening. Chomsky’s theory of syntax has been simplified, with Merge as the primary ingredient, requiring a ‘slight mutation’ producing a ‘slight rewiring of the brain’. These descriptions contrast with earlier notions of language as a bodily organ and an attempt to bring the evolution of language within evolutionary credibility. Minimalist theory places a greater burden on externalization to explain the complex grammars of the world’s languages. Sentence parsing relies on an internal device, Merge, applied recursively. The question is whether this internal structuring is ‘uniquely human (species-specific) and uniquely linguistic (domain-specific)’ or whether it depends on the way that experience and knowledge have been incrementally structured over millions of years of evolution.

Box 1. The Gestural Theory of Language Origins

Only humans can achieve vocal learning. Sign languages have all the hallmarks of true language. Language may have originated from manual gestures. Captive great apes have learned manual gestures in language-like ways, and great apes in the wild communicate bodily in language-like forms. People gesture manually while speaking, involving the hippocampus. Gestural communication may derive from the primate ‘mirror system’. In macaques, the system responds to actions perceived acoustically and visually but not to animal calls. Brain imaging shows it expanded to encompass the language circuit. During the Pleistocene, brain size increased, and hands were freed, allowing communication through gesture and mime. Mimed gestures were simplified and conventionalized over time. Human language might evolved in the service of gestural communication alone, and the vocal capacity is actually a very recent overlay. Speech is a system of gestures of the tongue, lips, and larynx. Movements of the hand and mouth are linked neurally, phylogenetically, developmentally, and behaviorally, suggesting mouth gestures might have blended into manual ones, and the visible movements of speech remain verbally informative. The acoustic code is more arbitrary and sustained through culture. The transition might be an early example of miniaturization. The shift to speech produced the ‘human revolution’. Subsequent shifts, from writing to the Internet, have shaped human culture.