The species-specific organizational property of speech is a continual mouth open-close alternation, the two phases of which are subject to continual articulatory modulation. The cycle constitutes the syllable, and the open and closed phases are segments framescontent displays that are prominent in many nonhuman primates. The new role of Broca's area and its surround in human vocal communication may have derived from its evolutionary history as the main cortical center for the control of ingestive processes. The frame and content components (...) of speech may have subsequently evolved separate realizations within two general purpose primate motor control systems: (1) a motivation-related medial system, including anterior cingulate cortex and the supplementary motor area, for self-generated behavior, formerly responsible for ancestral vocalization control and now also responsible for frames, and (2) a lateral system, including Broca's area and surround, and Wernicke's area, specialized for response to external input (and therefore the emergent vocal learning capacity) and more responsible for content. (shrink)

The article analyzes the neural and functional grounding of language skills as well as their emergence in hominid evolution, hypothesizing stages leading from abilities known to exist in monkeys and apes and presumed to exist in our hominid ancestors right through to modern spoken and signed languages. The starting point is the observation that both premotor area F5 in monkeys and Broca's area in humans contain a “mirror system” active for both execution and observation of manual actions, and that F5 (...) and Broca's area are homologous brain regions. This grounded the mirror system hypothesis of Rizzolatti and Arbib (1998) which offers the mirror system for grasping as a key neural “missing link” between the abilities of our nonhuman ancestors of 20 million years ago and modern human language, with manual gestures rather than a system for vocal communication providing the initial seed for this evolutionary process. The present article, however, goes “beyond the mirror” to offer hypotheses on evolutionary changes within and outside the mirror systems which may have occurred to equip Homo sapiens with a language-ready brain. Crucial to the early stages of this progression is the mirror system for grasping and its extension to permit imitation. Imitation is seen as evolving via a so-called simple system such as that found in chimpanzees (which allows imitation of complex “object-oriented” sequences but only as the result of extensive practice) to a so-called complex system found in humans (which allows rapid imitation even of complex sequences, under appropriate conditions) which supports pantomime. This is hypothesized to have provided the substrate for the development of protosign, a combinatorially open repertoire of manual gestures, which then provides the scaffolding for the emergence of protospeech (which thus owes little to nonhuman vocalizations), with protosign and protospeech then developing in an expanding spiral. It is argued that these stages involve biological evolution of both brain and body. By contrast, it is argued that the progression from protosign and protospeech to languages with full-blown syntax and compositional semantics was a historical phenomenon in the development of Homo sapiens, involving few if any further biological changes. Key Words: gestures; hominids; language evolution; mirror system; neurolinguistics; primates; protolanguage; sign language; speech; vocalization. (shrink)

"This reviewer had to be restrained from stopping people in the street to urge them to read it: They would learn something of the way science is done,...

David McNeill, a pioneer in the ongoing study of the relationship between gesture and language, here argues that gestures are active participants in both speaking and thinking. He posits that gestures are key ingredients in an “imagery-language dialectic” that fuels speech and thought. The smallest unit of this dialectic is the growth point, a snapshot of an utterance at its beginning psychological stage. In _Gesture and Thought,_ the central growth point comes from a Tweety Bird cartoon. Over the course of (...) twenty-five years, the McNeill Lab showed this cartoon to numerous subjects who spoke a variety of languages, and a fascinating pattern emerged. The shape and timing of gestures depends not only on what speakers see but on what they take to be distinctive; this, in turn, depends on the context. Those who remembered the same context saw the same distinctions and used similar gestures; those who forgot the context understood something different and changed gestures or used none at all. Thus, the gesture becomes part of the growth point—the building block of language and thought. _Gesture and Thought _is an ambitious project in the ongoing study of how we communicate and how language is connected to thought. (shrink)

A previous observational study suggested that when faced with a partner with its back turned, chimpanzees tend to move around to the front of a non-attending partner and then gesture — rather than gesturing once to attract attention and then again to convey a specific intent. We investigated this preference experimentally by presenting six orangutans, five gorillas, nine chimpanzees, and four bonobos with a food begging situation in which we varied the body orientation of an experimenter with respect to the (...) subject and the location of the food. These manipulations allowed us to measure whether subjects preferred to move around to face E or to use signals to attract her attention before they begged for food. Results showed that all species moved around to face E and then produced visual gestures, instead of using tactile/ auditory gestures behind E to call her attention. Species differences were apparent particularly when the food and E were in different locations. Unlike gorillas and orangutans, chimpanzees and bonobos produced their gestures in front of E in all conditions, including that in which subjects had to leave the food behind to communicate with her. Implications of these results are discussed in the context of the evolution of social cognition in great apes. (shrink)

Pointing by apes is near-ubiquitous in captivity, yet rare in their natural habitats. This has implications for understanding both the ontogeny and heritability of pointing, conceived as a behavioral phenotype. The data suggest that the cognitive capacity for manual deixis was possessed by the last common ancestor of humans and the great apes. In this review, nonverbal reference is distinguished from symbolic reference. An operational definition of intentional communication is delineated, citing published or forthcoming examples for each of the defining (...) criteria from studies of manual gestures in apes. Claims that chimpanzees do not point amongst themselves or do not gesture declaratively are refuted with published examples. Links between pointing and cognitive milestones in other domains relating means to ends are discussed. Finally, an evolutionary scenario of pointing as an adaptation to changes in hominid development is briefly sketched. (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)

This article argues for the gestural origins of speech and language based on the available evidence gathered in humans and nonhuman primates and especially from ape studies. The strong link between motor functions and speech in humans is reviewed. The presence of asymmetrical cerebral organization in nonhuman primates along with functional asymmetries in the perception and production of vocalizations and in intentional referential gestural communication is then emphasized. The nature of primate communicatory systems is presented, and the similarities and differences (...) between these systems and human speech are discussed. It is argued that recent findings concerning neuroanatomical asymmetries in the chimpanzee brain and the existence of both mirror neurons and lateralized use of hands and vocalizations in communication necessitate a reconsideration of the phylogenic emergence of the cerebral and behavioral prerequisites for human speech. (shrink)

For vocal animals, recognizing species-specific vocalizations is important for survival and social interactions. In humans, a voice region has been identified that is sensitive to human voices and vocalizations. As this region also strongly responds to speech, it is unclear whether it is tightly associated with linguistic processing and is thus unique to humans. Using functional magnetic resonance imaging of macaque monkeys (Old World primates, Macaca mulatta) we discovered a high-level auditory region that prefers species-specific vocalizations over other vocalizations and (...) sounds. This region not only showed sensitivity to the ‘voice’ of the species, but also to the vocal identify of conspecific individuals. The monkey voice region is located on the superior-temporal plane and belongs to an anterior auditory ‘what’ pathway. These results establish functional relationships with the human voice region and support the notion that, for different primate species, the anterior temporal regions of the brain are adapted for.. (shrink)