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)

A detailed account of human language and evolution, reconciling the apparent dichotomy between humans and all other animals. Focuses on the speculative presence of a Generative Assembly Device, unique to Homo sapiens.

To most people it seems obvious that there are major mental differences between ourselves and other species, but there is considerable debate over exactly how special our minds are, in what respects, and which were the critical evolutionary events that have shaped us. Some researchers claimlanguage as a solely human, even defining, attribute, while others claim that only humans are truly conscious. These questions have been explored mainly by archaeologists and anthropologists until recently, but this volume aims to show what (...) psychologists have to say on the evolution of mind. The book begins with a thorough overview of what is known of the non-primate mind and its evolution. Following this, an international range of experts discuss in temporal sequence the human mind at various stages of evolution, beginning with the pre-hominids of 20 million years ago and ending withcontemporary human behaviour. Accessible to students and researchers alike in psychology, anthropology, evolution, archaeology, and ethology, The Descent of Mind provides a range of provocative answers to the timeless question of what it means to be human. (shrink)

We present a new road map for research on “How the Brain Got Language” that adopts an EvoDevoSocio perspective and highlights comparative neuroprimatology – the comparative study of brain, behavior and communication in extant monkeys and great apes – as providing a key grounding for hypotheses on the last common ancestor of humans and monkeys and chimpanzees and the processes which guided the evolution LCA-m → LCA-c → protohumans → H. sapiens. Such research constrains and is constrained by analysis of (...) the subsequent, primarily cultural, evolution of H. sapiens which yielded cultures involving the rich use of language. (shrink)

One view of language is that it emerged in a single step in Homo sapiens, and depended on a radical transformation of human thought, involving symbolic representations and computational rules for combining them. I argue instead that language should be viewed as a communication system for the sharing of thoughts, and that thought processes themselves evolved well before the capacity to share them. One property often considered unique to language is generativity—the capacity to generate a potentially infinite variety of sentences. (...) I suggest that generativity is derived from the understanding of space and the capacity to recall or construct spatiotemporal scenarios, and probably goes far back in the evolution of animals that move in spatial habitats. Another property essential to language is theory of mind, the ability to understand what others are thinking, which probably emerged from animal empathy and became more complex in hominin evolution. Language evolved for the sharing of experiences, whether remembered or constructed, perhaps initially through pantomime but gradually conventionalized into standardized forms, including speech. These developments probably took place gradually during the Pleistocene, rather than as a sudden event in the evolution of H. sapiens. (shrink)

There is a growing interest in mental time travel in cognitive psychology, neuroscience, developmental psychology, comparative psychology, and evolutionary psychology. Here we review current issues in each of these disciplines. To help move the debates forward we name and distinguish 15 key hypotheses about mental time travel. We argue that foresight has for too long lived in the shadows of research on memory and call for further research efforts.

I argue that a critical feature of language that distinguishes it from animal communication isdisplacement,the means to communicate about the non-present. This implies a capacity for mental travels in time and space, which is the ability to call to mind past episodes, imagine future ones or purely fictitious ones, and locate them in different places. While mental travel in time, in particular, is often considered to be unique to humans, behavioral and neurophysiological evidence suggests that it is evident in some (...) form, at least, in nonhuman animals, including rodents, and may go far back in the evolution of animals that move. The linguistic capacity to share experiences that transcend space and time evolved much more recently, accelerating during the Pleistocene with increasing demands for effective cooperation and long-distance planning. The expansion of mental time travel probably co-evolved with the development of language itself, because the sharing of memories, plans, and stories vastly added to our own individual experiences. From this perspective, the critical period of the Road Map runs from the emergence of the genusHomoaround 2 million years ago to the present. (shrink)

Euan Macphail’s work and ideas captured a pivotal time in the late 20th century when behavioral laws were considered to apply equally across vertebrates, implying equal intelligence, but it was also a time when behaviorism was challenged by the view that language was unique to humans, and bestowed a superior mental status. Subsequent work suggests greater continuity between humans and their forebears, challenging the Chomskyan assumption that language evolved in a single step {“the great leap forward”) in humans. Language is (...) now understood to be based on an amalgam of cognitive functions, including mental time travel, theory of mind, and what may be more broadly defined as imagination. These functions probably evolved gradually in hominin evolution and are present in varying degrees in nonhuman species. The blending of language into cognition provides both for interspecies differences in mental function, and continuity between humans and other species. What does seem to be special to humans is the ability to communicate the contents of imagination, although even this is not absolute, and is perhaps less adaptive than we like to think. (shrink)

Language is commonly held to be unique to humans, and to have emerged suddenly in a single “great leap forward” within the past 100,000 years. The view is profoundly anti-Darwinian, and I propose instead a framework for understanding how language might have evolved incrementally from our primate heritage. One major proposition is that language evolved from manual action, with vocalization emerging as the dominant mode late in hominin evolution. The second proposition has to do with the role of language as (...) a means of communicating about events displaced in space and time from the present. Some have argued that mental time travel itself is unique to human, which might explain why language itself is uniquely human. I argue instead that mental time travel has ancient evolutionary origins, and gradually assumed narrative-like properties during the Pleistocene, when language itself began to take shape. (shrink)

Recognising that signed languages are true languages adds to the variety of forms that languages can take. Such recognition also allows one to differentiate those aspects of language that depend on the medium (voiced or signed) from those that depend on more cognitive aspects. At least some aspects of language, such as symbolic representation, time markers, and generativity, may derive from the communication of the products of mental time travel, and from the sharing of remembered past and planned future episodes.

Language anomalies and left-hemisphere dysfunction are commonly reported in schizophrenia. Additional evidence also suggests differences in the integration of information between the hemispheres. Bilateral gain is the increase in accuracy and decrease in latency that occurs when identical information is presented simultaneously to both hemispheres. This study measured bilateral gain in controls and individuals with schizophrenia using a lexical-decision task where word or non-word judgements were made to letter strings presented in the left visual field , right visual field or (...) bilaterally . Language was not abnormally lateralized in the schizophrenia group. Controls exhibited the expected decrease in latency when words were presented bilaterally. This effect was not observed in the schizophrenia group who were actually disadvantaged in this condition. The lack of bilateral gain in schizophrenia is discussed as arising from differences in the connections between areas in each hemisphere that mediate language. (shrink)

Population-level asymmetry may be maintained, not by an “evolutionarily stable strategy” pitting a dominant bias against its nondominant opposite, but rather by a genetically based system pitting a directional bias against the absence of any such bias. Stability is then achieved through a heterozygotic advantage, maintaining balanced polymorphism. This model may better capture the fundamental trade-off between lateralization and bilateral symmetry.

I enlarge on the theme that the brain mechanisms required for languageand other aspects of the human mind evolved through selective changes in the regulatory genes governing growth. Extension of the period of postnatal growth increases the role of the environment in structuring the brain, and spatiotemporal programming ofgrowth might explain hierarchical representation, hemispheric specialization, and perhaps sex differences.

Many commentators have raised issues concerning the idea that language evolved from manual gestures. I deal with these first, reiterating the points that speech is very different from animal vocal calls, and that cortical control over manual action provided the best platform for the evolution of intentional communication and language. I then deal with commentaries on the origins of handedness. The critical questions are whether there is indeed an evolutionary coupling between handedness and lateralized control of speech, and if there (...) is, whether a prior lateralization of vocal control provided the nudge that gave most of us left-sided speech and right-handedness. (shrink)