Story on the evolution of vision in humans & primates:
Opinion: For Human Eyes Only
New York Times, 1/13/07
"Trying to explain why the whites of human eyes are larger than those of other primates leads to one of the deepest and most controversial topics in the modern study of human evolution: the evolution of cooperation."
Tomasello describes some fascinating work in which he & his colleagues study how humans & primates follow their fellow's eye / head movement. Human infants, it seems, follow eye movements and ignore head movements of their mothers, while primates follow head movement and don't pay much attention to eye movement of other primates.
Tomasello says "One possible answer, what we have called the cooperative eye hypothesis, is that especially visible eyes made it easier to coordinate close-range collaborative activities in which discerning where the other was looking and perhaps what she was planning, benefited both participants."
Browse some Google results for "Cooperative Eye Hypothesis" for more info, or check out his article in the Journal of Human Evolution; "Reliance on head versus eyes in the gaze following of great apes and human infants: the cooperative eye hypothesis." In Press, Corrected Proof, Available online 20 October 2006, by Michael Tomasello, Brian Hare, et al. ($30 for the non-library savvy, or request from Interlibrary Loan).