Morton (Research Zoologist/National Zoological Park, Washington, D.C.) and Page (former science editor of Smithsonian) tell it like they think it is when it comes to animal and human talk. The star performers here are birds, particularly the Carolina wren, a virtuoso singer with an extended repertoire. The authors use birds to illustrate a number of general principles. For example, wrens vary the acoustics of their songs to achieve the maximum delivery of sound with minimum degradation over distance- -the point being to warn interlopers away from the singer's turf by implying that the singer is close by. Indeed, birds use the extent of degradation of song as a measure of distance, paying less heed to a degraded song but reacting aggressively to a high-quality rendition. These are just some of the ideas percolating through a text whose general theme is that animal talk has evolved as a means of increasing fitness and that the nature of the talk depends as much on the perceiver as on the speaker. Animal talk increases in sophistication with the degree of social interaction and dependency, and with the complexity of the environment. Furthermore, there are commonalities across species, such as the use of low-pitched growls for aggression and high-pitched whines or cries to appeal for aid or to inspire affiliative behavior. The authors conclude that human speech does not represent a sharp break in nature, but lies along a continuum of all animal communication. Our close relatives among hominids and primates may have reached a stage of preadaptation for language (through brain lateralization) that included the ability to distinguish consonantal sounds, which ultimately led to linking consonants and vowels in phonemes. A neat Darwinian approach that is sure to arouse controversy. (Four line drawings.)
