EVOLUTION OF THE EAR AND HEARING - ISSUES AND QUESTIONS

The ear appears to have arisen early in the evolution of the vertebrat es. While there are significant interspecific differences in ear struc ture, it appears that receptor cell structure and the basic function o f the ear and auditory system are similar among all vertebrate groups. In this paper we present the evolution of the sensory hair cells of t he ear, the origins of the ear itself, and selected functions of the s ense of hearing. We argue that there have been strong selective pressu res in most vertebrate groups for the sorts of sound encoding and proc essing abilities that result in the efficient detection, localization, and identification of sound sources in noisy environments. Many of th e encoding and processing strategies underlying these functions are sh ared as well.