HOW DOES EVOLUTION DESIGN A BRAIN CAPABLE OF LEARNING LANGUAGE?

Compositionality, Metaphor, and the Evolution of Language

One of the great unknowns in language evolution is the transition from unstructured sign combination to grammatical structure. This paper investigates the central — while hitherto overlooked — role of functor–argument metaphor. This type of metaphor pervades modern language, but is absent in animal communication. It arises from the semantic clash between the default meanings of terms. Functor–argument metaphor became logically possible in protolanguage once sufficient vocabulary and basic compositionality arose, allowing for novel combinations of terms. For example, the verb to hide, a functor, could be combined not only with a concrete, spatial entity like food as its argument, but also with an abstract, non-spatial one like anger. Through this clash, to hide is reinterpreted as a metaphorical action. Functor–argument metaphor requires the possibility of term combinability and the existence of compositionality. At the same time, it transcends compositionality, forcing a non-literal interpretation. We argue that functor–argument metaphor led the development of protolanguage into fully-fledged language in multiple ways. Not only did it expand expressiveness, but it drove the development of syntax including the conventionalization and fixation of word order, and the development of demonstratives. Thus, functor–argument metaphor fills in multiple gaps in the trajectory from a protolanguage, with only some terms and simple term combinations, to the elaborate grammatical structures of fully-fledged human languages.

Cerebral localization of functions and the neurology of language: fact versus fiction or is it something else?

Over the last 15 years there has been a burgeoning number of publications using functional brain imaging (>40,000 articles based on an ISI/Web of Science search) to localize behavioral and cognitive processes to specific areas in the human brain that are often not confirmed by traditional, lesion-based studies. Thus, there is a need to reassess what cerebral localization of functions is and is not. Otherwise, there is no rational way to interpret the escalating claims of localization in the functional imaging literature that is taking on the appearance of neurophysiologic "phrenology". This article will present arguments to suggest that functional localization in the brain is a robust but very dynamic, four-dimensional process. It is a learned phenomenon driven over time by large-scale, spatially distributed, neural networks seeking to efficiently maximize the processing, storage, and manipulation of information for cognitive and behavioral operations. Because of historical considerations and space limitations, the main focus will be on localization of language-related functions whose theoretical neurological basis can be generalized for any complex cognitive-behavioral function.

Visualizing vocal perception in the chimpanzee brain

The study of nonhuman primate vocal-auditory behavior continues to provide novel insights into the origins of human language. However, data on the neural systems involved in the perception and processing of conspecific vocalizations in great apes are virtually absent in the scientific literature, yet are critical for understanding the evolution of language. Here we used positron emission tomography to examine the neurological mechanisms associated with the perception of species-specific vocalizations in chimpanzees. The data indicate right-lateralized activity in the chimpanzee posterior temporal lobe, including the planum temporale, in response to certain calls, but not others. In addition, important differences are apparent when these data are compared with those published previously from monkey species suggesting that there may be marked differences in the way chimpanzees and macaque monkeys perceive and process conspecific vocalizations. These results provide the first evidence of the neural correlates of auditory perception in chimpanzees and offer unprecedented information concerning the origins of hemispheric specialization in humans.