THE YEAR IN COGNITIVE NEUROSCIENCE 2009 The Evolution of Language Michael C. Corballis Department of Psychology, University of Auckland, Auckland, New Zealand Language, whether spoken or signed, can be viewed as a gestural system, evolving from the so-called mirror system in the primate brain. In nonhuman primates the gestural system is well developed for the productions and perception of manual action, especially transitive acts involving the grasping of objects. The emergence of bipedalism in the hominins freed the hands for the adaptation of the mirror system for intransitive acts for communication, initially through the miming of events. With the emergence of the genus Homo from some 2 million years ago, pressures for more complex communication and increased vocabulary size led to the conventionalization of gestures, the loss of iconic representation, and a gradual shift to vocal gestures replacing manual ones— although signed languages are still composed of manual and facial gestures. In parallel with the conventionalization of symbols, languages gained grammatical complexity, perhaps driven by the evolution of episodic memory and mental time travel, which involve combinations of familiar elements—Who did what to whom, when, where, and why? Language is thus adapted to allow us to share episodic structures, whether past, planned, or fictional, and so increase survival fitness. Key words: language; evolution; gesture; FOXP2; mirror neurons Introduction Is language evolution “the hardest problem in science,” as recently suggested (Christiansen & Kirby 2003, p. 1)? Certainly, it has had an extraordinarily difficult and contentious his- tory. In early times, at least, part of the diffi- culty has been religious, but that in turn might relate to the seemingly miraculous flexibility and open-endedness of language. In Christian thought it was proclaimed that language must be a gift from God: “In the beginning,” says St. John in the Bible, “was the Word, and the Word was with God, and the Word was God.” This view constrained philosophical thinking well into the second millennium AD. In the 17th century, R´ en´ e Descartes (1985/1647) con- sidered that language allowed such freedom of expression that it could not be reduced to Address for correspondence: Michael C. Corballis, Department of Psychology, University of Auckland, Auckland, New Zealand. m.corballis@auckland.ac.nz mechanical principles, confirming for him, at least, that it must indeed be God-given. Non- human animals, on the other hand, were mere automata, and therefore incapable of human- like language. Descartes has been called the founder of modern philosophy, but his views on language clearly left little scope for an evo- lutionary account. The publication of Darwin’s Origin of Species in 1859 should have encouraged a more evo- lutionary approach but was quickly followed in 1866 by the famous ban on all discussion of the origin of language by the Linguistic Society of Paris. The ban was reiterated in 1872 by the Philological Society of London. These suppres- sive moves may well have been influenced by the religious opposition to Darwin’s theory of natural selection but may have also been mo- tivated by the apparent uniqueness of human language, the absence of material evidence as to how it evolved, and the speculative nature of any discussion. In more recent times, discussion of language evolution was further stifled by the views of The Year in Cognitive Neuroscience 2009: Ann. N.Y. Acad. Sci. 1156: 19–43 (2009). doi: 10.1111/j.1749-6632.2009.04423.x C  2009 New York Academy of Sciences. 19