Insectopedia (48 page)
Nonetheless, at the very least, the natural world’s indifference should make us wary of assuming too quickly that flowers that draw our eye are similarly seductive to a pollinator. Such hidden truths make visible one important fact about vision (our own and that of other beings): it is a property not only of the viewer and the object but also of the relationship between them.
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The closer we look, the more we see. Bee masks and UV photos are not just intriguing; they’re beguiling. If we could only re-create an insect’s visual apparatus, they promise, we could see what it sees, and if we could see
what
it sees … why, then we could see
as
it sees, too. But I doubt many of us, including scientists and exhibit designers, believe this. Vision is so much more than mechanics.
The Soviet entomologist Georgii Mazokhin-Porshnyakov drew attention to this long ago: “When we talk about vision,” he wrote in the late 1950s, “we imply not only that animals are able to distinguish objects visually (i.e., the stimuli), but also that they are able to recognize them.”
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Photoreception, on its own, he suggested, is of little value to an organism; what counts is the ability to identify an object and make some sense of it. Reception presupposes perception. Insects see with their brain, not their eyes.
In this respect, an insect’s vision is identical to that of a human. Like ours, an insect’s vision is a complex sorting procedure, a way to filter and hierarchize objects in the world, one sense among several interdependent senses, one entangled element of perception.
Frederick Prete, a biologist at DePaul University who studies the visual universe of praying mantises, points out that until quite recently the standard scientific assumption was that insect vision operated by exclusion, that bees, butterflies, wasps, mantises, and similar creatures were designed “to ignore all but some very limited, specific types of visual information … [such as] a small, moving, fly-shaped spot just a few millimeters away … [or] yellow flowers of a certain size.” Instead, Prete and his colleagues demonstrate, mantises and many other insects deal with sensory information in ways not dissimilar from those of humans: “they use categories to classify moving objects; [and] they learn and use complex algorithms to solve difficult problems.” Prete describes human processing of visual information as a type of taxonomy:
We filter sensory information by recognizing and assessing certain key characteristics of the events and objects around us, and we use that information
to identify an event or object as an example of a general class of events or objects. For instance, you would not reject a meal … because it did not look like a specific, idealized plate of food. You would assess its characteristics (odor, color, texture, temperature), and if they all met certain criteria, you would take a bite. In this case, the novel meal is an example of the category “acceptable meal.” Likewise, we can learn that a particular task—mending a ripped curtain, for instance—is an example of the category “sewing material together.” So, when attempting to mend a curtain for the first time, we apply the rules that we learned are successful in other, analogous mending tasks. In other words, we have acquired and employ an algorithm, or “rule of thumb” for solving specific problems of this general type.
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A mantis, write Prete and his colleague Karl Kral, is confronted by a large number of potential meals in the course of a day, and like us, it both creates and deploys a relational category (“a theoretical, perceptual envelope”) that corresponds to the thought “acceptable meal.” To evaluate an object, the animal draws on experience—learned from past events and encounters—to assess a series of “stimulus parameters” that include the object’s size (if it is compact), its length (if it is elongated), the contrast between the object and its background, the object’s location in the mantis’s visual field, the object’s speed, and the object’s overall direction of movement.
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A varying number of these criteria must be met for the mantis to strike. Yet, rather than a reaction being triggered by the meeting of a specific threshold, the mantis takes into account the relationship among different data in each parameter. Kral and Prete call this calculation a “perceptual algorithm” (and make the not-unreasonable point that if it were described in primates, it would be considered abstract reasoning).
Along with a small number of other invertebrate scientists who integrate behavioral and neuroanatomical studies in what is sometimes called psychophysiological research (that is, research on the connections between the psychological and physiological aspects of behavior), Kral and Prete write un-self-consciously of the complexity of insect behavior, of the correspondence between the ways insects and vertebrates (including humans) make sense of the world, and of the insect’s
mind.
But maybe these insects are just a little too calculating, modeled a little
too much on the rational actors of classical economic theory (who we know from our own experience don’t really exist). Maybe they’re not lively and spontaneous enough. How do we know they always calculate solely according to the logic of the hunter? Might they have other desires? Or maybe this is exactly how mantises are even if we don’t have to assume that butterflies, say, or fruit flies proceed in this way too. No matter; this is thought-provoking work: there is a cognition here, say Kral and Prete, that is dependent on but somehow not reducible to physiology. Yet, if cognitive processes are irreducible to electrochemical function, what exactly are they? Nobody seems very sure.
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It’s worth noting that these questions are central to contemporary neuroscience, the interdisciplinary field concerned with the study of the nervous systems of animals. Neuroscience is dedicated to physiological explanation but is nonetheless deeply preoccupied with questions of mind, with such indeterminate phenomena as consciousness, cognition, and perception, with material solutions to what many might consider ontological or even metaphysical problems. In neuroscience, it is axiomatic that the brain is the center of all animal life—“the key philosophical theme of modern neural science is that all behavior is a reflection of brain function” begins a standard reference work.
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“Higher-order” brain functions, such as metacognition (thinking about thinking) and emotion, tend to be understood as functional outcomes of brain anatomy and physiology.
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Yet the model of perception that overlies this straightforward if controversial principle is formidably elaborate. Perception is conceived as a set of dynamic, interactive brain functions that integrate cognition and experience and include filtering, selection, prioritization, and other forms of active and flexible information management in the context of previously unimagined neuroplasticity. One example might be the interplay between the brain and particular visually salient objects, such that the objects instantly and without conscious registration are isolated within a saturated and nonhierarchical visual field. Such ideas are fully congruent with the type of perceptual algorithm developed for insects by Kral and Prete (and others; see, for example, the two decades of work on honeybee cognition carried out by Mandyam Srinivasan and his team at Australian National University). Yet this parallelism between people and
invertebrates would, I suspect, seem foolish to many neuroscientists, for whom the marvelous size and complexity of the modern hominid brain—specifically the number of its neural connections—is the decisive marker of human exceptionalism.
Kral and Prete are likely to find still less support in the social sciences and humanities, though for different reasons. Research on vision here emphasizes the role of culture and history in mediating between the human eye and the world.
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For cultural analysts, physiology often provides little more than a set of possibilities for a complex human perceptual engagement with the world. How humans see and what we see are understood as profoundly shaped by social and cultural history. Vision, and perception more generally, are neither unchanging in time nor constant across cultures.
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They have history—several histories, in fact, as the character of perceptual understanding is understood to be shaped by regional and national aesthetic cultures. Key moments of transformation are tied to the emergence of specific visual technologies. In the West, for example, among other moments, scholars have drawn attention to the invention and dissemination of linear perspective in the fifteenth century and the shift in the nineteenth century to a preoccupation with surface morphologies: the preoccupation with the superficialities of objects and bodies with which we still live.
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In these accounts, vision—the ways in which we observe people and things, the forms of categorization that are embedded in our own ways of looking, and the technologies through which we, in turn, are seen, surveilled, classified, assessed—is central to the ways in which we understand ourselves and are understood by others; it is a source of culture-history-society as well as its outcome.
Such a different vision of vision! Unlike the isolated neurobiological brain, the social brain is immersed in a world that is itself overflowing with meaning, is deeply part of a universe in which even so-called natural phenomena are always simultaneously both biophysical and cultural-historical, so that colors, for example, are always at the same time both measurable wavelength and shimmering story (in which we can’t escape knowing that pink—whether it works for us or not—is cuter than navy blue). In this vision, people
learn
to see, and the form and content of that learning are specific to time and place. A man blinded years before recovers his sight and must be taught to recognize perspective in culturally
effective ways; a woman leaves the closed forest in which she has spent her life and has to make radical, even traumatic adjustments before understanding the spatiality of the urban landscape that is now her home.
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Yet history, politics, and aesthetics—the central categories employed by cultural theorists to explore vision—are by definition exclusively human, are, in fact, definitively, classically, human. Though their proponents may disagree about almost everything else, when it comes to human exceptionalism, there is an emphatic alliance between the social brain, with its immersion in culture, and the neurobiological brain, preoccupied as it is with size and physiological complexity. And the differences on which these competing visions converge are surely not trivial. How can we hold on to them and at the same time refuse their implicit hierarchy?
“The best of the [insect] eyes,” wrote the optical-instrument maker Henry Mallock in 1894, “would give a picture about as good as if executed in rather coarse wool-work and viewed at a distance of a foot.” Indeed, Mallock continued, a compound eye with the resolution of a human eye would itself be a spectacle. Mallock estimated its diameter at more than sixty feet.
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Why so monstrous? Because to adequately counter diffraction—the tendency of light to spread out and blur as it passes through a narrow opening—each lens in every one of the many facets of the compound eye would require a diameter of 0.08 inches, the size of a human pupil—small, perhaps, but an eightyfold increase for a bee.
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Mallock’s fantastic notion—the insect head: outsize, outrageous, but not horrific, not Cronenberg’s fly—makes me want to climb back into one of those Lucite masks! Even though I know that they don’t really work, that there’s far more to vision than this, the urge to see through another’s eyes isn’t easily suppressed. And I’m far from alone. So many people have been driven to try it, the more scientifically minded concocting ingenious ways to record the view directly, delicately scraping out the
eye’s internal structures, removing the retina, cleaning the cornea, experimenting with light, microscopes, cameras, the product less immersive than a mask but more objective seeming, more authentic feeling. This impulse to capture the vision of another being is potent, and I believe I’m right in thinking it derives its power from the unusual coincidence it creates between the two visions of vision we’re caught in here: the promise of the natural sciences (that is, the revelation of how things work, a revelation of structure and function that is often ultimately rather unrevealing) and the inaccessible dream of the human sciences (the utopian dissolution of ontological difference, the impossible yearning to enter another self). The most recondite mysteries are resolvable, the impulse tells us. Everything can be illuminated.
Anton van Leeuwenhoek, the discoverer of bacteria, sperm, and blood cells, of the mouthparts and stings of bees, of animal motion in a droplet of water, and of many, many other microbiological phenomena, was the first to see the gleam in a compound eye. Shining a candle through an insect’s cornea, he used one of the gold and silver compound microscopes of his own invention, one of the microscopes sold by his family after his death and now lost, one of the microscopes that Robert Hooke copied to access the unimagined and deeply disturbing world he laid bare with his draftsman’s precision in
Micrographia
, the volume that includes his famous engraving of a dragonfly’s head—its diabolical masklike face made visible for the very first time—and in which he recorded his disbelieving observation that reflected perfectly from each of the facets of the animal’s compound eye was “a Landscape of those things which lay before my window, one thing of which was a large Tree, whose trunk and top I could plainly discover, as I could also the parts of my window, and my hand and fingers, if I held it between the Window and the Object.”
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