It is a truth both obvious and profound that all creatures perceive the world via their own unique sensory mechanisms. Thus, when the philosopher Thomas Nagel wrote his oft-cited essay “What Is It Like to Be a Bat?,” ethologists as well as nonscientists couldn’t help agreeing with his conclusion: We don’t know, and the deeply frustrating reality is that we probably never will.
Not only is each individual necessarily separated from every other, but members of different species are even more cordoned off, not merely as a matter of existential isolation and loneliness, but as a genuine, hard-core, physical, and biological fact.
Of course, we human beings can take advantage of elaborate technologies, through which we create remarkable prosthetic extensions of our senses—not just hearing aids and eyeglasses, but binoculars, telescopes, Geiger counters, ultraviolet and infrared sensors, cosmic-ray detectors, ultra-sensitive seismic-monitoring devices, and so forth.
But when it comes to perceiving and making “sense” of information received, we’re still stuck within our own heads. Even when we record the ultrasonic vocalizations of a bat, we nonetheless “hear” them with the brains and minds of Homo sapiens.
Those strains of thought came to mind after a simple yet notable wildlife encounter. Reading a book recently at my campsite in a lovely and gloriously remote part of the central Oregon high desert, I happened to look up at the same moment that a turkey vulture glided very low—perhaps 25 feet above me—such that the sun reflected with astonishing brilliance off its shockingly red naked head.
As a field biologist, I have had numerous encounters with free-living wildlife all over the world, including cherished observations of some of our rarest creatures. Truth be told, turkey vultures are neither rare nor, for the most part, especially cherished. Still, this simple event left an impression on me.
First was the dramatic fact that an animal, of the sort typically seen wheeling in the sky at relatively great distance, had suddenly come so close. Even more notable, however, was the sense of surprise: I hadn’t been looking for the bird, nor was I responding to any sensory impression that had invaded my consciousness. How, then, had this convergence been achieved?
As for the vulture, it is likely that the bird simply wanted to check out a possible meal, which brings to mind the wonderful poem, “Vulture,” in which Robinson Jeffers recounts:
"… I saw through half-shut eyelids a vulture wheeling high up in heaven,
And presently it passed again, but lower and nearer, its orbit narrowing, I understood then
That I was under inspection. I lay death-still and heard the flight-feathers
Whistle above me and make their circle and come nearer.
I could see the naked red head between the great wings
Bear downward staring. I said, “My dear bird, we are wasting time here.
These old bones will still work; they are not for you.” But how beautiful he looked, gliding down
On those great sails …"
But what about me? I can readily explain why the vulture looked down, but why did I look up, and at just exactly the right time? I’d bet that, like Mr. Jeffers when he heard those flight-feathers whistle, I also heard—or maybe somehow glimpsed—the approaching critter, but that unlike the poet, my “perception” was muffled and thus somehow below my conscious awareness.
This brings me back to the ethologists’ recognition that organisms possess “windows unto the world” that are unique to themselves, and barely if at all understood by us.
In his classic treatise, A Stroll Through the Worlds of Animals and Men, the pioneering ethologist Jakob J. von Uexküll (1864-1944) introduced the important concept of umwelt, often translated into English as “environment,” but more correctly seen as the perceptual world as perceived by the animal, to be distinguished from the umgebung, which refers to the “real,” objective environment.
Von Uexküll famously discussed the umwelt of a tick, whose feeding behavior effectively involves of only three sensory inputs: (1) the odor of butyric acid, produced by mammals; (2) the temperature of 37 degrees Celsius, the body temperature of said mammals; and (3) the presence of hair or fur, whereupon the tick proceeds to burrow into its prey.
In a similarly renowned but more recent study, nicely titled “What the Frog’s Eye Tells the Frog’s Brain,” biologists led by the electrophysiologist Jerome Y. Lettvin reported in 1959 that bullfrog eyes transmit to their amphibian brains only a highly schematized version of the real world, based on the selective firing of a limited number of receptor cells, including some specialized for perceiving moving dots (“bug detectors”), others responding only to large moving edges (“predator detectors”), and so forth. In short, nothing even remotely like what we perceive.
Of course, the living world is also replete with creatures whose umwelten are far more sensitive than ours, but along axes of which we have limited experience: bats that “hear” in the ultrasonic, salmon that smell their way upstream, “weakly electric” fish that create an electric field around their bodies and use deformations in the field to discriminate rocks from prey, snakes with exquisite sensitivity to the body temperature of a small rodent, honeybees that see different “shades” of ultraviolet as well as being able to discriminate the plane of polarization of sunlight, ants with a vast array of pheromones—different and highly specific chemicals that convey information about what trail to follow, who is a friend and who a foe, whether a neighboring ant is dead and therefore needs to be carried out of the nest … the list is enormous.
There is more to the world as perceived by other creatures than we know, probably more than we can even imagine. And in other cases, considerably less! Moreover, when it comes to ourselves, we are also strangers even to our own perceptions. We don’t have the visual acuity of a vulture, but we may well be capable of gathering and acting upon far more information than we consciously realize, and sometimes, as a result, we catch a glimpse of things strangely beautiful, all the more so because they are unexpected.
David Barash is an evolutionary biologist and professor of psychology at the University of Washington, whose most recent book is "Homo mysterious: evolutionary puzzles of human nature" (Oxford University Press, 2012).