~ Pergamon Neuropsychologia, Vol. 33, No. 12, pp. 1637-1646, 1995 Copyright~ 1995 Elsevier Science Ltd Printedin Great Britain. All rightsreserved DO28-3932[95$9.50 + 0.D0 0028-3932(95)00043-7 LATERALIZATION OF PREDATOR-EVASION RESPONSE IN A TELEOST FISH (GIRARDINUS FALCATUS) CLAUDIO CANTALUPO,*t ANGELO BISAZZAt and GIORGIO VALLORTIGARA~: tDipartimento di Psicologia Generale, Universifft di Padova, Italy; and ~:Istituto di Filosofia, Pedagogia, Didattica deUe Lingne Moderne, Universit~ di Udine, Italy (Received 9 January 1995; accepted 16 March 1995) Al~traet--Evidence of lateral asymmetries in the direction of turning during escape behaviour in a species of poeciliid fish, Girardinus falcatus, is reported. When repeatedly faced with a simulated predator (in five successive sessions, spaced 7 days apart), immature Girardinusfalcatus exhibited a significant population bias to turn fight on the first session and a progressive bias to turn left in subsequent sessions. Mature Girardinus were then tested to check whether the shift in the direction of turn with repeated sessions depended on maturation or habituation. It was found that adult Girardinus showed a slight population bias to turn right in the first session and a strong subsequent bias to turn left after repeated sessions. The implications of these findings to our current understanding of the evolution of brain lateralization are discussed. Key Words: brain lateralization; evolution of lateralization; teleost fish; predator evasion; poeciliid fish; Girardinus falcatus. INTRODUCTION Evidence for brain lateralization is now widespread among both mammals and birds (reviews in Refs. [3, 10, 57]). It is unclear, however, whether this should be interpreted as reflecting basic homology or parallel but independent evolutionary histories. Various authors have suggested that the functional significance of lateralization may be to prevent conflict of response emission arising from visual input of two laterally placed (largely monocular) eyes [5, 11]. Although this explanation may offer a selective pressure for the initial independent evolution of lateral asymmetries in different classes, it does not specifically explain the pattern of convergence in the direction of the asymmetries in species as different as birds and mammals. Mice [20], rats [22], Japanese macaques [42], passerine birds [39, 40] and humans [10] all show a dominance of the left hemisphere in the production and/or perception (e.g. zebra finches [41]) of acoustic signals. Though it is not clear whether the crucial factor is the communicative significance [43] or the temporal processing of auditory sequences (see Fitch et al. [22]), the similarity remains nonetheless impressive. Furthermore, humans [10], rhesus monkeys [26], chimpanzees [38], and chicks [52, 53] all show a right hemisphere advantage in individual recognition of familiar conspecifics. The right hemisphere is also selectively involved in the production of facial expression in humans [50] and monkeys *To whom all correspondence should be addressed. 1637