Current research on the organization and function of the visual system in primates

All primates, including humans, are highly visual creatures.1-3 We rely heavily on visual cues for basic adaptive behaviors such as finding food, mates, and shelter; as well as more complex behaviors such as parental care and the formation of social hier-archies. Throughout the course of primate evolution, our dependence on visual cues has increased with each adaptive advantage acquired from visually guided behavior; and so has the demand for greater and more efficient processing of visual information in primate brains. Consequently, the number, size, and complexity of brain structures involved in visual processing has expanded dramatically in the primate order, far more than those of any other species in the mammalian lineage.2,4 As we have learned to interact with the world using visual cues, our brains have evolved to absorb, manipulate, and react to visual information in increasingly effective ways. Individual brain structures dedicated to vision in primates also frequently exhibit anatomical and functional specializations that are not present in other mammals. These adaptations are not present in most nonprimate mammals, partly because many species rely on other sensory modalities for their individual behaviors. Thus, understanding how we, as humans, perceive the visual world around us begins with learning how vision is processed in the primate brain. Furthermore, learning how vision in primates differs both structurally and functionally from vision in nonprimate mammals, and determining how those changes enable adaptive traits in the primate lineage, will allow us to understand the truly unique phenomenon of human visual behavior.