Two major studies which are explored in this paper concern the comparative morphology of a wide range of primates, how these differences affect behavior, and what inferences one can make regarding the adaptive reasons behind those differences. Hiromi Kobayashi and Shiro Kohshima conducted a study in 1998 that measured the eyes of 88 species of primates using computer-aided image analysis to determine the differences between species and to examine how these differences correlate with biological and environmental variability (Kobayashi & Kohshima 2001). Michael Tomasello and associates have carried out numerous studies using apes, monkeys, and children that explore issues relating to cognition and communication; this body of work is integrated into the “cooperative eye hypothesis,” which will be explored in the body of this paper (Tomasello et al. 2007:316).