Abstract:
<p>Most vertebrates possess some overlap of the right and left visual fields. The region of overlap, the binocular field, contains unique visual cues that provide an accurate estimate of distance and three-dimensional shape. The fact that animal's might use these cues to guide behavior has several interesting implications to the study of</p><p>primate evolution. While there is an abundance of data suggesting that many animals perceive binocular cues, there is little evidence demonstrating binocular information is advantageous during ecologically relevant behaviors. </p><p>The data presented here for cats, rats, and lemurs supports the hypothesis that a loss of binocular cues alters locomotion on discontinuous substrates. The alteration in performance is interpreted as a shift to a more conservative kinematic strategy associated with an increase in uncertainty regarding the precise location of the substrate. One interpretation of this finding is that early primates would have had access to visuomotor transformations allowing them to use binocular cues to guide precise movements. As forelimbs lengthened and became more mobile, the binocular visual field also increased to help place the forelimbs on complex discontinuous substrates. While this is the most straightforward reading of my experiments on locomotion, the precise placement of long mobile forelimbs is likely to be important in a wide range of circumstances. The role of forward facing eyes in primate origins remains one of the most intriguing questions in physical anthropology.</p>
