The sensory systems of Alouatta: Evolution with an eye to ecology

Abstract

Our knowledge about the perceptual world of howler monkeys is unevenly distributed between the five senses. Whereas there is abundant knowledge about the sense of vision in the genus Alouatta, only limited data on the senses of hearing, smell, taste, and touch are available. The discovery that howler monkeys are the only genus among the New World primates to possess routine trichromacy has important implications for the evolution of color vision and therefore has been studied intensively. Detailed information about the genetic mechanisms and physiological processes underlying color vision in howler monkeys are available. Although the sound production, vocal repertoire, and acoustic communication in the genus Alouatta have been well documented, basic physiological measures of hearing performance such as audiograms are missing. Similarly, despite an increasing number of observational studies on olfactory communication in howler monkeys, there is a complete lack of physiological studies on the efficiency of their sense of smell. Information about the senses of taste and touch is even scarcer and mainly restricted to a description of their anatomical basis. A goal of this chapter is to summarize our current knowledge of the anatomy, physiology, genetics, and behavioral relevance of the different senses in howler monkeys in comparison to other platyrrhines.