a1 Department of Psychology, Cornell University, Ithaca, NY 14853, and Santa Fe Institute, Santa Fe, NM 87501 [email protected] http://www.psych.cornell.edu/people/Faculty/mhc27.html
a2 Division of Psychology and Language Sciences, University College London, London, WC1E 6BT, United Kingdom [email protected] http://www.psychol.ucl.ac.uk/people/profiles/chater_nick.htm
It is widely assumed that human learning and the structure of human languages are intimately related. This relationship is frequently suggested to derive from a language-specific biological endowment, which encodes universal, but communicatively arbitrary, principles of language structure (a Universal Grammar or UG). How might such a UG have evolved? We argue that UG could not have arisen either by biological adaptation or non-adaptationist genetic processes, resulting in a logical problem of language evolution. Specifically, as the processes of language change are much more rapid than processes of genetic change, language constitutes a “moving target” both over time and across different human populations, and, hence, cannot provide a stable environment to which language genes could have adapted. We conclude that a biologically determined UG is not evolutionarily viable. Instead, the original motivation for UG – the mesh between learners and languages – arises because language has been shaped to fit the human brain, rather than vice versa. Following Darwin, we view language itself as a complex and interdependent “organism,” which evolves under selectional pressures from human learning and processing mechanisms. That is, languages themselves are shaped by severe selectional pressure from each generation of language users and learners. This suggests that apparently arbitrary aspects of linguistic structure may result from general learning and processing biases deriving from the structure of thought processes, perceptuo-motor factors, cognitive limitations, and pragmatics.
Morten H. Christiansen is Associative Professor in the Department of Psychology and Co-Director of the Cognitive Science Program at Cornell University (Ithaca, New York). His research focuses on the interaction of biological and environmental constraints in the processing, acquisition, and evolution of language, which he approaches using a variety of methodologies, including computational modeling, corpus analyses, psycholinguistic experimentation, neurophysiological recordings, and molecular genetics. Christiansen is the author of more than 90 scientific papers and has edited volumes on Connectionist Psycholinguistics, Language Evolution, and, most recently, Language Universals.
Nick Chater is Professor of Cognitive and Decision Sciences at University College London, United Kingdom. He is the author of more than 150 scientific publications in psychology, philosophy, linguistics, and cognitive science, and has written or edited eight books. He currently serves as Associate Editor for Psychological Review. Chater has also served as Associate Editor for the journal Cognitive Science and on the Editorial Boards of Psychological Review and Trends in Cognitive Sciences. His research explores formal models of inference, choice, and language.