Toolmaking requires motor skills that in turn require handedness, so that there is no competition between the two sides of the brain. Thus, handedness is not necessarily linked to vocalization but to the origin of causal beliefs required for making complex tools. Language may have evolved from these processes.

In a dynamic world, mechanisms allowing prediction of future situations can provide a selective advantage. We suggest that memory systems differ in the degree of flexibility they offer for anticipatory behavior and put forward a corresponding taxonomy of prospection. The adaptive advantage of any memory system can only lie in what it contributes for future survival. The most flexible is episodic memory, which we suggest is part of a more general faculty of mental time travel that allows us not only (...) to go back in time, but also to foresee, plan, and shape virtually any specific future event. We review comparative studies and find that, in spite of increased research in the area, there is as yet no convincing evidence for mental time travel in nonhuman animals. We submit that mental time travel is not an encapsulated cognitive system, but instead comprises several subsidiary mechanisms. A theater metaphor serves as an analogy for the kind of mechanisms required for effective mental time travel. We propose that future research should consider these mechanisms in addition to direct evidence of future-directed action. We maintain that the emergence of mental time travel in evolution was a crucial step towards our current success. (shrink)

The strong predominance of right-handedness appears to be a uniquely human characteristic, whereas the left-cerebral dominance for vocalization occurs in many species, including frogs, birds, and mammals. Right-handedness may have arisen because of an association between manual gestures and vocalization in the evolution of language. I argue that language evolved from manual gestures, gradually incorporating vocal elements. The transition may be traced through changes in the function of Broca's area. Its homologue in monkeys has nothing to do with vocal control, (...) but contains the so-called “mirror neurons,” the code for both the production of manual reaching movements and the perception of the same movements performed by others. This system is bilateral in monkeys, but predominantly left-hemispheric in humans, and in humans is involved with vocalization as well as manual actions. There is evidence that Broca's area is enlarged on the left side in Homo habilis, suggesting that a link between gesture and vocalization may go back at least two million years, although other evidence suggests that speech may not have become fully autonomous until Homo sapiens appeared some 170,000 years ago, or perhaps even later. The removal of manual gesture as a necessary component of language may explain the rapid advance of technology, allowing late migrations of Homo sapiens from Africa to replace all other hominids in other parts of the world, including the Neanderthals in Europe and Homo erectus in Asia. Nevertheless, the long association of vocalization with manual gesture left us a legacy of right-handedness. Key Words: cerebral dominance; gestures; handedness; hominids; language evolution; primates; speech; vocalization. (shrink)

In this paper I discuss scientific and philosophical issues related to the interdisciplinary area of Neurolinguistics, focusing on the origin and nature of human language. What kind of evolutionary process leads to the emergence of language? I propose that this process began with the adoption of bipedalism, triggering the co-evolution of new brain structures and forms of social organization. This process created a context that favoured the emergence of articulated vocalization using a combinatorial linguistic system. The identification of sufficient conditions (...) for the emergence of human language in this context depends on the paradigm adopted for the analysis. I look for a synthesis of nativist and constructivist paradigms, showing that both contribute to an understanding of the origin and nature of human language. (shrink)

Humans grasp discrete infinities within several cognitive domains, such as in language, thought, social cognition and tool-making. It is sometimes suggested that any such generative ability is based on a computational system processing hierarchical and recursive mental representations. One view concerning such generativity has been that each of the mind’s modules defining a cognitive domain implements its own recursive computational system. In this paper recent evidence to the contrary is reviewed and it is proposed that there is only one supramodal (...) computational system with recursion in the human mind. A recursion thesis is defined, according to which the hominin cognitive evolution is constituted by a recent punctuated genetic mutation that installed the general, supramodal capacity for recursion into the human nervous system on top of the existing, evolutionarily older cognitive structures, and it is argued on the basis of empirical evidence and theoretical considerations that the recursion thesis constitutes a plausible research program for cognitive science. (shrink)

The presence of asymmetry in the human cerebral hemispheres is detectable at both the macroscopic and microscopic scales. The horizontal expansion of cortical surface during development (within individual brains), and across evolutionary time (between species), is largely due to the proliferation and spacing of the microscopic vertical columns of cells that form the cortex. In the asymmetric planum temporale (PT), minicolumn width asymmetry is associated with surface area asymmetry. Although the human minicolumn asymmetry is not large, it is estimated to (...) account for a surface area asymmetry of approximately 9% of the region’s size. Critically, this asymmetry of minicolumns is absent in the equivalent areas of the brains of other apes. The left-hemisphere dominance for processing speech is thought to depend, partly, on a bias for higher resolution processing across widely spaced minicolumns with less overlapping dendritic fields, whereas dense minicolumn spacing in the right hemisphere is associated with more overlapping, lower resolution, holistic processing. This concept refines the simple notion that a larger brain area is associated with dominance for a function and offers an alternative explanation associated with “processing type.” This account is mechanistic in the sense that it offers a mechanism whereby asymmetrical components of structure are related to specific functional biases yielding testable predictions, rather than the generalization that “bigger is better” for any given function. Face processing provides a test case – it is the opposite of language, being dominant in the right hemisphere. Consistent with the bias for holistic, configural processing of faces, the minicolumns in the right-hemisphere fusiform gyrus are thinner than in the left hemisphere, which is associated with featural processing. Again, this asymmetry is not found in chimpanzees. The difference between hemispheres may also be seen in terms of processing speed, facilitated by asymmetric myelination of white matter tracts ( Anderson et al., 1999 found that axons of the left posterior superior temporal lobe were more thickly myelinated). By cross-referencing the differences between the active fields of the two hemispheres, via tracts such as the corpus callosum, the relationship of local features to global features may be encoded. The emergent hierarchy of features within features is a recursive structure that may functionally contribute to generativity – the ability to perceive and express layers of structure and their relations to each other. The inference is that recursive generativity, an essential component of language, reflects an interaction between processing biases that may be traceable in the microstructure of the cerebral cortex. Minicolumn organization in the PT and the prefrontal cortex has been found to correlate with cognitive scores in humans. Altered minicolumn organization is also observed in neuropsychiatric disorders including autism and schizophrenia. Indeed, altered interhemispheric connections correlated with minicolumn asymmetry in schizophrenia may relate to language-processing anomalies that occur in the disorder. Schizophrenia is associated with over-interpretation of word meaning at the semantic level and over-interpretation of relevance at the level of pragmatic competence, whereas autism is associated with overly literal interpretation of word meaning and under-interpretation of social relevance at the pragmatic level. Both appear to emerge from a disruption of the ability to interpret layers of meaning and their relations to each other. This may be a consequence of disequilibrium in the processing of local and global features related to disorganization of minicolumnar units of processing. (shrink)

The gestural repertoire of captive gorillas contains the so-called “hand-on“ (or “pat-off“) gesture in which one animals puts its flat hand on top of another's head, which often leads to cessation of the receiver's previous activity. We investigate the origins of this gesture and developmental aspects of gesture creation. We further analyze gesture form and use in relation to the age of the sender with special consideration of the reaction of the receiver to better explain the function of the hand-on. (...) The focus of the study is to compare this gesture across different age groups in gorillas in regard to both production and reception and to get insights into possible origins of the gesture. (shrink)

Recent interest in the origins of language, within the strongly cognitive field of Evolutionary Psychology, has predominantly focused upon the origins of syntax (cf. Hurford, Knight, & Studdert-Kennedy, 1998). However, Ullin Place's (2000a) theory of the gestural origins of language also addresses the more fundamental issue of the antecedents of symbols, and does so from a behaviorist perspective, stressing the importance of the peculiarly human ability to form stimulus equivalence classes. The rejection by many developmental psychologists of a behaviorist account (...) of language acquisition has led to a modular and distinctly nativist psychology of language (cf. Pinker, 1994, 1997; Pinker & Bloom, 1990). Little has been said about the role or nature of learning mechanisms in the evolution of language. Although Place does not provide any defense of a behaviorist linguistic ontogeny, this is no reason to rule out his phylogenetic speculations. We aim to outline Place's evolutionarily parsimonious view of symbol origins and their relation to stimulus equivalence. We applaud Ullin Place for bringing symbols into focus within the broader discipline of language origins and suggest that he has raised an interesting set of questions to be discussed in future work. (shrink)

The evolution of cognition literature is dominated by views that presume the evolution of underlying neural structures. However, recent models of cognition reemphasize the role of physiological structures, development, and external resources as important components of cognition. This article argues that these alternative models of cognition challenge our understanding of human cognitive evolution. As a case study, it focuses on rehabilitating bipedalism as a crucial moment in human evolution. The australopithecines are often seen as “merely” bipedal chimpanzees, with a similar (...) suite of behaviors. But an embodied, developmental approach to understanding australopithecine cognitive abilities shows that the transition between australopithecines and the emergence of the Homo genus is less of a break than is often thought. Bipedalism on this view is not just a physiological and behavioral breakthrough: it represents a major cognitive leap as well. (shrink)