Perceptual and Acoustic Evidence for Species-Level Differences in Meow Vocalizations by Domestic Cats (Felis catus) and African Wild Cats (Felis silvestris lybica) Nicholas Nicastro Cornell University To test for possible anthropogenic selection effects on meows in domestic felids, vocalizations by domestic cats (Felis catus) were compared with cries by their closest wild relative, the African wild cat (Felis silvestris lybica). Comparisons included analysis of acoustic characteristics and perceptual studies with human (Homo sapiens) listeners. The perceptual studies obtained human listener ratings of call pleasantness. Both the acoustic and perceptual comparisons revealed clear species-level differences: The domestic cat meows were significantly shorter in mean duration than the wild cat meows, showed higher mean formant frequencies, and exhibited higher mean fundamental frequencies. Human listeners at all levels of experience and affinity for cats rated domestic cat meows as far more pleasant sounding than wild cat vocalizations. These results are consistent with a model of cat domestication that posits selective pressure on meows based on human perceptual biases. Domestication has been defined as “the capture and taming by man of wild animals of a species with particular behavioral char- acteristics, their removal from their natural living area and breed- ing community, and their maintenance under controlled breeding conditions for mutual benefits” (Bo ¨ko ¨nyi, 1989, p. 22, 1969; Bo ¨ko ¨nyi, 1989). A predictable consequence of reproductive isola- tion, founder effects, and controlled breeding has been that do- mesticated animals look and behave differently from their ances- tors. These differences were widely appreciated at the dawn of evolutionary theory itself (Darwin, 1859/1993), and our under- standing continues to develop (Clutton-Brock, 1989, 1999). In general, most domestic animals are held to have smaller brains on average than their wild counterparts, exhibit changes in superficial coloring, have less acute senses, and have higher thresholds against stress due to conspecific crowding and proximity to hu- mans (Hemmer, 1990). In addition to the physical and physiological changes associated with domestication, changes in communicative behavior (poten- tially including production, usage and/or reception; cf. Seyfarth & Cheney, 1997) seem probable. Cameron-Beaumont (1997) has considered what might be either the elaboration or the outright origination of the physical signal “tail up” in the domestic cat (Felis catus). Analogous changes in the vocal behavior of com- panion animals have also been suggested, such as acoustic differ- ences in dog barks correlated with behavioral contexts typical of dog– human interaction (Yin, 2002). Studies of social gaze in dogs have suggested canine capabilities of “reading” the posture, head position, and eyes of humans that compare favorably to those reported for chimpanzees (Hare & Tomasello, 1999) and even for 3-year-old children (Soproni, Miklo ´si, Topa ´l, & Csa ´nyi, 2001). Controlled experiments involving dog– owner play communication have concluded that dogs can competently interpret certain inten- tional movements of humans (T. D. McKinley & Sambrook, 2000; Rooney, Bradshaw, & Robinson, 2001). Vocal communication is an important dimension of cat– human interaction, in part because vocal communication is so important to human caretakers. The meow, in particular, seems to be associated with vocal communication to people. The meow is defined here as a quasiperiodic sound with at least one band of tonal energy enhanced by the resonant properties of the vocal tract. The call ranges between a fraction of a second to several seconds in duration. The pitch profile is generally arched, with resonance changes often reflected in formant shifts that give the call a diphthong-like vowel quality. Although all meows in this study were mainly periodic sounds, this call type very often includes atonal features (Wilden, Herzel, Peters, & Tembrock, 1998) and garnishments (trills or growls) that may serve to differentiate the calls perceptually. Although meows are among the most common cat-to-human vocalizations (Bradshaw & Cameron-Beaumont, 2000), they are observed infrequently in cat-to-cat interactions (S. L. Brown, 1993). Animal rescue workers have noted that the meow is largely absent in unsocialized feral cats, appearing only on regular contact with human caretakers (Franklin, 2002; S. Greene, personal com- munication, April 25, 2002). Only a handful among the approxi- mately 40 species in the family Felidae produce meow-type calls. These include Felis silvestris silvestris (European wild cat), Ca- racal caracal (caracal), Leopardus wiedii (margay), an unspecified member of the Lynx genus (reviewed in Bradshaw & Cameron- Nicholas Nicastro was supported by National Institute of Mental Health Predoctoral Research Fellowship T32 MN 19389 during preparation of this study. He thanks Ferdie Schoemann, Claudia Schra, Elsie Birdenhann, and Nathaniel Taweni of the National Zoological Gardens, Pretoria, South Africa for their assistance in the wild cat studies and domestic cat own- ers Leslie Horowitz, Thomas Volman, Isabel Tovar, Jill Mateo, Darryl Mayeaux, S. K. List, Karl and Pamela Reichert, and Robert and Linda Newton. He gives additional thanks to Michael Owren for his advice and support for this and previous cat studies. Correspondence concerning this article should be addressed to Nicholas Nicastro, Department of Psychology, Cornell University, 243 Uris Hall, Ithaca, NY 14853. E-mail: nn12@cornell.edu Journal of Comparative Psychology Copyright 2004 by the American Psychological Association 2004, Vol. 118, No. 3, 287–296 0735-7036/04/$12.00 DOI: 10.1037/0735-7036.118.3.287 287