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In Favor of Animal Consciousness
From: University of Chicago Press
| By:
Donald R. Griffin |
EDITOR'S INTRODUCTION |
 If animals are capable of simple thoughts, as many scientists now believe, are they conscious as well? In Animal Minds: Beyond Cognition to Consciousness, published by the University of Chicago Press, Donald R. Griffin (right) seeks to answer this question in the affirmative. Recognizing that human consciousness is exceedingly more complex than any conceivable animal thinking, Griffin explores compelling scientific evidence regarding the obscure nature of animal consciousness. Mindful of the fact that "consciousness" itself is a difficult term to express definitively, he urges his audience to err on the side of caution when judging what's inside the minds of animals. |
 hungry chimpanzee walking through his native rain forest comes upon a large Panda oleosa nut lying on the ground under one of the widely scattered Panda trees. He knows that these nuts are much too hard to open with his hands or teeth and that although he can use pieces of wood or relatively soft rocks to batter open the more abundant Coula edulis nuts, these tough Panda nuts can only be cracked by pounding them with a very hard piece of rock. Very few stones are available in the rain forest, but he walks 80 meters straight to another tree where several days ago he had cracked open a Panda nut with a large chunk of granite. He carries this rock back to the nut he has just found, places it in a crotch between two buttress roots, and cracks it open with a few well-aimed blows. (The loud noises of chimpanzees cracking nuts with rocks had led early European explorers to suspect that some unknown native tribe was forging metal tools in the depths of the rain forest.) |
In a city park in Japan, a hungry green-backed heron picks up a twig, breaks it into small pieces, and carries one of these to the edge of a pond, where she drops it into the water. At first it drifts away, but she picks it up and brings it back. She watches the floating twig intently until small minnows swim up to it, and she then seizes one by a rapid thrusting grab with her long, sharp bill. Another green-backed heron from the same colony carries bits of material to a branch extending out over the pond and tosses the bait into the water below. When minnows approach this bait, he flies down and seizes one on the wing. |
Must we reject, or repress, any suggestion that the chimpanzees or the herons think consciously about the tasty food they manage to obtain by these coordinated actions? Many animals adapt their behavior to the challenges they face either under natural conditions or in laboratory experiments. This has persuaded many scientists that some sort of cognition must be required to orchestrate such versatile behavior. For example, in other parts of Africa chimpanzees select suitable branches from which they break off twigs to produce a slender probe, which they carry some distance to poke it into a termite nest and eat the termites clinging to it as it is withdrawn. Apes have also learned to use artificial communication systems to ask for objects and activities they want and to answer simple questions about pictures of familiar things. Vervet monkeys employ different alarm calls to inform their companions about particular types of predator. |
Such ingenuity is not limited to primates. Lionesses sometimes cooperate in surrounding prey or drive prey toward a companion waiting in a concealed position. Captive beaver have modified their customary patterns of lodge- and dam-building behavior by piling material around a vertical pole at the top of which was located food that they could not otherwise reach. They are also very ingenious at plugging water leaks, sometimes cutting pieces of wood to fit a particular hole through which water is escaping. Under natural conditions, in late winter some beaver cut holes in the dams they have previously constructed, causing the water level to drop, which allows them to swim about under the ice without holding their breath. |
Nor is appropriate adaptation of complex behavior to changing circumstances a mammalian monopoly. Bowerbirds construct and decorate bowers that help them attract females for mating. Plovers carry out injury-simulating distraction displays that lead predators away from their eggs or young, and they adjust these displays according to the intruder's behavior. A parrot uses imitations of spoken English words to ask for things he wants to play with and to answer simple questions such as whether two objects are the same or different, or whether they differ in shape or color. Even certain insects, specifically the honeybees, employ symbolic gestures to communicate the direction and distance their sisters must fly to reach food or other things that are important to the colony. |
These are only a few of the more striking examples of versatile behavior on the part of animals. Although these are not routine everyday occurrences, the fact that animals are capable of such versatility has led to a subtle shift on the part of some scientists concerned with animal behavior. Rather than insisting that animals do not think at all, many scientists now believe that they sometimes experience at least simple thoughts, although these thoughts are probably different from any of ours. For example, Terrace (1987, 135) closed a discussion of "thoughts without words" as follows: "Now that there are strong grounds to dispute Descartes' contention that animals lack the ability to think, we have to ask just how animals do think." Because so many cognitive processes are now believed to occur in animal brains, it is more and more difficult to cling to the conviction that this cognition is never accompanied by conscious thoughts. |
Conscious thinking may well be a core function of central nervous systems. For conscious animals enjoy the advantage of being able to think about alternative actions and select behavior they believe will get them what they want or help them avoid what they dislike or fear. Of course, human consciousness is astronomically more complex and versatile than any conceivable animal thinking, but the basic question addressed in this book is whether the difference is qualitative and absolute or whether animals are conscious even though the content of their consciousness is undoubtedly limited and very likely quite different from ours. There is of course no reason to suppose that any animal is always conscious of everything it is doing, for we are entirely unaware of many complex activities of our bodies. Consciousness may occur only rarely in some species and not at all in others, and even animals that are sometimes aware of events that are important in their lives may be incapable of understanding many other facts and relationships. But the capability of conscious awareness under some conditions may well be so essential that it is the sine qua non of animal life, even for the smallest and simplest animals that have any central nervous system at all. When the whole system is small, this core function may therefore be a larger fraction of the whole. |
The fact that we are consciously aware of only a small fraction of what goes on in our brains has led many scientists to conclude that consciousness is an epiphenomenon or trivial by-product of neural functioning, as discussed by Harnad (1982). But the component of central nervous system activity of which we are consciously aware is of special significance, because it is what makes life real and important to us, as discussed in detail by Siewert (1998). Insofar as other species are conscious, the same importance may well be manifest. Animals may carry out much of their behavior quite unconsciously. Many may never be conscious at all. But insofar as they are conscious, this is an important attribute. |
Although nonconscious information processing could in theory produce the same end result as conscious thinking, as emphasized by Shettleworth (1998) and others, it seems likely that conscious thinking and emotional feeling about current, past, and anticipated events is the best way to cope with some of the more critical challenges faced by animals in their natural lives. As pointed out by the philosopher Karl Popper (1978), what he termed "mental powers" are very effective in coping with novel and unpredictable challenges. This is especially true of many animals under natural conditions, where mistakes are often fatal. The effectiveness of conscious thinking and guiding behavioral choices on the basis of emotional feelings about what is liked or disliked may well be so great that this core function is one of the most important activities of which central nervous systems are capable. |
Defining consciousness
No one seriously denies that we experience conscious thoughts and subjective feelings, even though we cannot describe them with complete accuracy and therefore no one else can experience them exactly as we do. The question under consideration in this book is the extent to which nonhuman animals also experience something of the same general nature as the subjective feelings and conscious thoughts that we know at first hand. The content of an animal's conscious experience may be quite different from any human experience. It may ordinarily be limited to what the animal perceives at the moment about its immediate situation, but sometimes its awareness probably includes memories of past perceptions or anticipations of future events. An animal's understanding may be accurate or misleading, and the content of its thoughts may be simple or complex. A conscious animal must often experience some feeling about whatever engages its attention. Furthermore, any thinking animal is likely to guide its behavior at least partly on the basis of the content of its thoughts, however simple or limited these may be. |
The content of animal consciousness
Animal thoughts and emotions presumably concern matters of immediate importance to the animals themselves, rather than kinds of conscious thinking that are primarily relevant to human affairs. Consciousness is not an all-or-nothing attribute. It varies widely within our species, and it would be remarkable if the content of every animal's consciousness were identical. Conscious thinking and strong emotional feelings can ordinarily deal with only one or a very few things at a time. Large, complex animals must also be able to organize and retain information about innumerable perceptions and potential actions of which only one or a very few can be the focus of conscious awareness at any one moment. |
Recognizing that an animal's consciousness may be quite different from any human thoughts and feelings makes the problem of identifying and analyzing it more difficult. We may, however, tend to exaggerate this difficulty, because many basic concerns are likely to be very similar for most animals that have any conscious experiences at all. Hunger and desire for food, fear of dangers, affection, and hatred may well have much in common for any animal that experiences them. Once we give up the implicit assumption that any conscious experiences of other animals must be a subset of human experiences, we are faced with the difficulty of determining, or indeed even clearly imagining, what such nonhuman experiences are actually like to the animals who experience them. For instance, the range of odors that various animals can distinguish, and to which they react in different ways, suggests variations in subjective emotional feelings that odors may elicit. If a particular species of animal is capable of some type of conscious experience that our brains cannot generate, how can we ever hope to learn what it is? Although total and perfect understanding seem at first to be beyond our reach, enterprising investigation can probably achieve significant if incomplete understanding. |
Sensory and perceptual capabilities are an obvious category in which interspecies differences are probably large and important and in which we can anticipate a beginning of such investigation. The philosopher Thomas Nagel (1974) aroused great interest by raising the question "What is it like to be a bat?" He chose this example because bats' reliance on echolocation, detecting obstacles and capturing rapidly moving prey by hearing echoes of one's own sounds, seems at first glance so remote from any human experience as to be truly beyond our ken. But this specific example may not be as telling as it seems on first hearing. For blind people also carry out a form of echolocation, detecting objects by hearing echoes of sounds they make. To be sure, human echolocation is severely limited compared to that of bats and dolphins with respect to the types of targets that can be detected and discriminated from each other, and especially with respect to the ability to distinguish relevant echoes from competing sounds. But the fact remains that despite enormous differences in resolution and practical usefulness many blind people, and also well-practiced blindfolded subjects, do make good use of echolocation, as reviewed by Griffin (1958) and Rice (1967). |
The case of human echolocation has an intriguing and perhaps significant further ramification. Many blind people succeed quite well at echolocation but do not realize that they are detecting objects by their sense of hearing. Yet if they are prevented from making any sounds, if their hearing is blocked, or if they are subjected to masking noise, they lose almost completely their previous ability to detect obstacles and avoid collisions with them, as demonstrated by the meticulous experiments of Supa, Cotzin, and Dallenbach (1944). But this specialized type of auditory discrimination is not wholly divorced from consciousness. Many other skillful users of echolocation are well aware that they detect obstacles by hearing some difference in the sound of their voices, footsteps, cane taps, or other sounds they have found to be helpful in finding their way. Echolocation is of course only one case in which sensory or perceptual input channels to the central nervous system differ from those with which we are familiar. But it is an instructive example of how critical scientific investigation can lead to understanding of behavioral and subjective experiential phenomena that at one time appeared mysterious and inexplicable. |
Approaches to animal awareness
The ethologist Marian Dawkins (1993, 1998) has contributed significantly to the recognition of the central importance of emotions in cognitive ethology. She has developed procedures by which an animal's preferences can be evaluated by allowing it to choose between different environments. More recently she has critically analyzed evidence for animal consciousness and the difficulties of determining whether animals have conscious experiences. Her basic conclusion is that at least mammals and birds are probably conscious at times but that there are many pitfalls that must be carefully avoided in scientific attempts to determine the existence and content of animal consciousness. She sums up the balance of evidence as follows: "Our near-certainty about (human) shared experiences is based, amongst other things, on a mixture of the complexity of their behavior, their ability to 'think' intelligently and on their being able to demonstrate to us that they have a point of view in which what happens to them matters to them. We now know that these three attributes--complexity, thinking and minding about the world--are also present in other species. The conclusion that they, too, are consciously aware is therefore compelling. The balance of evidence (using Occam's razor to cut us down to the simplest hypothesis) is that they are and it seems positively unscientific to deny it" (1993, 177). |
Recognizing that we cannot be certain which animals are conscious, R. Bradshaw (1998, 108) and others recommend that when issues of animal welfare are concerned it is best to "assume animals do have consciousness in case they do; if they do not it does not matter." |
Evidence suggesting animal consciousness
There are several types of scientific evidence that provide promising insights into what life is like for various animals. One category of evidence is the versatility with which many animals adjust their behavior appropriately when confronted with novel challenges. Animals encounter so many unpredictable challenges under natural conditions that it would be very difficult if not impossible for any combination of genetic instructions and individual experience to specify in advance the entire set of actions that are appropriate. But thinking about alternative actions and selecting one believed to be best is an efficient way to cope with unexpected dangers and opportunities. In theory such versatility might result from nonconscious information processing in the brain. But conscious thinking may well be the most efficient way for a central nervous system to weigh different possibilities and evaluate their relative advantages. |
The comparative analysis of consciousness
Despite the renaissance of scientific and philosophical interest in consciousness, one of the most significant and promising approaches to the general question has been largely neglected. This is what biologists call the comparative method: analyzing an important function in a variety of species in which it occurs, sometimes in simpler forms, in which it can be studied more effectively without the many interacting complications that obscure its basic properties in the more complicated animals. Crick and Koch (1998), leaders in the renewal of scientific studies of consciousness, take it for granted that monkeys are conscious. But they prefer to defer investigating nonhuman consciousness because they claim that "when one clearly understands, both in detail and in principle, what consciousness involves in humans, then will be the time to consider the problem of consciousness in much simpler animals" (97). |
Restricting scientific investigation to the most complex of all known brains may be unwise, however, for insofar as consciousness can be identified and analyzed in a variety of animals, certain species might turn out to be especially suitable for investigating its basic attributes. Obvious analogies are the use of fruit flies for investigations of genetics, squid giant axons for analyzing the biophysics of nerve conduction, laboratory rats and pigeons for studies of learning, and Aplesia for detailed analysis of the cellular and molecular basis of learning. It would have been unwise for the early investigators of genetics or learning to limit their research to primates, and the same may be true for contemporary and future studies of consciousness. |
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