Inside of a Dog_ What Dogs See, Smell, and Know - Alexandra Horowitz [50]
Dog-eyed
It takes all of six seconds for Pump to go from masterful to maladroit. In the first five she flawlessly navigates the brambles and bushes and thick-trunked trees that web the opening of the forest into field to catch a fast-moving tennis ball. It thonks off a tree and she's there to nearly vacuum it into her mouth. An apparition of a dog tears in out of nowhere, a racing blur of white fur and bark. Pump notes him and hurtles away, evading this stealer of tennis balls. In that sixth second, she stops, suddenly adrift. She's lost track of me. I watch her search: erect body, head high. I'm within sight; I smile at her. She looks at and past me, not seeing me. Instead, she spots the large, limping, heavy-coated man who came through with the white tear. She takes off after him. I must run to retrieve her. The moment before Pump was all-seeing; now she's a fool.
There is an intrinsic ranking of the modes by which we humans sense the world—and vision is winner by a long shot. Eyes arouse great interest in human psychologists; they betoken much more than one might imagine just from their physical form. However pretty a nose one might have, however close the forehead is to the brain, neither our noses nor foreheads nor cheeks nor ears are granted such importance.
We are visual animals. There's barely a challenge for second, either: audition is part of nearly every experience we have. Olfaction and touch might duke it out for third, and taste runs a distant fifth. Not that each of these isn't important to us on any particular occasion. The loveliness of presentation of, say, a tiered wedding cake would be undercut if vinegar replaced the anticipated taste of unmitigated sweetness. Or if any odor besides that of baked goods emanated from the cake—or if the first bite was not soft and yielding, but crunchy or slimy. Still, on most occasions we first direct our gaze to a new scene or object. If we notice something unusual or unexpected on the sleeve of our jacket, we turn to examine it with our eyes. Vision would have to really fail to provide any information before we decide to learn about it by inhaling it closely or taking a bold lick.
The order of operations is turned upside-down for dogs. Snout beats eyes and mouth beats ears. Given the olfactory acuity of dogs, it makes sense that vision plays an accessory role. When a dog turns his head toward you, it is not so much to look at you with his eyes; rather, it is to get his nose to look at you. The eyes just come along for the ride. You may be a recipient of an imploring gaze by a dog across the room right now. But can dogs even see what we do?
In many ways, the visual system of a dog—a subsidiary means to look at the world—is very much like our own. Its demotion behind other senses, in fact, may allow dogs to see details with their eyes that we overlook with ours.
One might well ask what a dog would even need eyes for. They can navigate and find food with their remarkable noses. Anything that needs closer examination goes right in the mouth. And they can identify each other through that sensory apparatus squished between their mouth and nose, the vomeronasal organ. As it turns out, they have at least two critical uses of their eyes: to complement their other senses and to see us. The natural history of the dog eye, seen in the story of their forebears, wolves, explains the context in which their vision evolved. It is a happy and transformative side effect that