While reading Brian Christian’s evocative new book The Most Human Human, which manages to explore an impressively wide and variegated territory while covering the secondary contest at an annual Turing Test competition to determine which human entrant seems most human, I ran across this random fun fact:
…. Humans are known to have the largest and most visible sclera—the “whites” of the eyes—of any species…. There must be some reason humans developed it, despite its obvious costs. In fact, the advantage of visible sclera—so goes the “cooperative eye hypothesis”—is precisely that it enables humans to see clear, and from a distance, which directions other humans are looking…. Chimpanzees, gorillas, and bonobos—our nearest cousins—follow the direction of each other’s heads, whereas human infants follow the direction of each other’s eyes.
All evolved traits have costs associated with them. A peacock develops his tail to attract a peahen at great nutritive cost. In fact, he does so as a way of signaling, “I must be really special because I can squander resources on this utterly useless and even detrimental fancy fanny fan.” So likewise, there must have been costs to developing these large and prominent sclera of ours. The most obvious leaping to my mind is the fact that when I can easily see what other people are looking at, they can just as easily do the same with me. This is mutual mind-reading, plain and simple. And we have to assume that being able to read each others’ minds was ultimately more advantageous to our forbears than permanent obfuscation. We were stronger when we understood each other well. We still are.
As usual, I see implications for theatre. A while ago I posted here an essay explaining why solo shows are not plays, and therefore not, strictly speaking, theatre. I conceded, however, that they belong to the even older art of story-telling. Now, based on some of the newest science available, I am no longer convinced it really is the elder form.
Communication based on gesture, eye movement and even sympathetic neuronal patterning (more on that later when I abstract research on “mirror neurons”) may well have preceded verbal communication, which leans so heavily on semantic content. Put more simply, our evolutionary ancestors may have been “play-acting” long before they were “story-telling”.