The Accidental Species: Misunderstandings of Human Evolution (29 page)

In one experiment, a western scrub jay buries some food in full view of other jays, but will then return when no other jays are around, unearth the cache, and bury it somewhere else. Significantly, the jays that rebury their food in private are those that had been thieves of the caches of others in the past. The conclusion seems clear—the jay pictures itself as a participant in a drama in which it guesses the intentions of other jays close by, which would be to steal its food store. The jay seems to be able to put itself in the minds of its fellows, imagining what it would do in a similar situation.
³
Sentience is a valuable asset for any social animal, but with sentience comes deceit. It is probably no coincidence that very young children are very bad liars until around the age of three, when they first acquire a “theory of mind” and can put themselves in the shoes of others. By the same token, people with autism-spectrum disorders can have great difficulty in social situations because they have trouble reading the emotional states of
others,
⁴
and must learn by intellection what others seem to absorb by instinct. Autism-spectrum disorders might therefore be seen as disorders of sentience.

Sentience, however, is not an unalloyed benefit . . .

Hold it right there: how can something that seems so beneficial, so wonderful, that it might easily be seen as the final attainment of humanity, the justification of an exalted place as the acme and purpose of Creation, the final revelatory light that switches on in our minds, from which flows all art, culture, science, and indeed everything that seems to make human life so much richer and more distinctive from that of any other organism, be seen as in any way a disadvantage?

Well, let’s start with something we all know, and some of us remember with much toe-curling embarrassment: our teenage years. One might interpret the extreme self-consciousness of teenagers, whose brains are undergoing drastic remodeling before the final attainment of adulthood,
⁵
as a disarming and sometimes crippling excess of sentience. Teenagers try to grapple, perhaps for the first time in their lives, with age-old questions—questions such as the meaning of existence, man’s inhumanity to man, and so on—that their parents have long abandoned in favor of more tractable problems, such as the location of one’s spectacles, or the identity of whoever it was that put the Benzedrine in Mrs. Murphy’s Ovaltine.
⁶
It’s perhaps no accident that the greatest artists, poets, musicians, mathematicians, and even scientists tend to do their best work when they are young, when their self-knowledge is at its peak. To paraphrase Tom Lehrer: when Mozart was my age, he’d been dead for fifteen years.

Everyone who’s been a teenager will have experienced the same agonies of self-consciousness, and will have been relieved, frankly, when that fit’s over. But if teenage sentience can be a handicap, just imagine how difficult life would be, intolerable even, if we were sentient
all the time
.

When one is learning a new skill, whether it’s a sport, driving a car, or learning a musical instrument, one is often painfully aware of every movement one makes, and wonders if one will ever get the hang of it. With practice, however, the movements we make as we perform these tasks become automatic, wired into those parts of the brain that do things without our having to be conscious of them.

That’s why an experienced driver, say, will be able to drive along a
familiar route literally without thinking about every turn of the wheel, every press on the gas or the brake, and will be able to take evasive action (such as swerving out of the path of an oncoming vehicle, or applying the brakes before a potential collision) faster than conscious thought would seem to allow. When a driver finishes his journey, he will not be able to recall the precise sequence of actions he took as he drove, as he would were he a computer. A concert pianist will be able to play a complex, learned piece by letting her fingers do the walking with what musicians call “muscle memory,” using the sheet music only as a backup.

I believe that we live most of our lives in this way. Just as we don’t give conscious thoughts to routine, learned habits such as driving, we do not, as a rule, record in any self-conscious way the moments of our lives as they pass. When you look back at one day lived, you recall a small series of incidents as blurry snapshots, not every single moment as you lived it in exhaustive detail. The vast bulk of the time through which we travel is passed in a state of insentience.

In fact, I’d go so far as saying that most people live most of their lives without much being troubled by sentience. Is this not a somewhat snobbish attitude? To be sure, you could see it that way, but consider the alternative—and if you do, you’ll see that it is almost too horrible to contemplate.

The Argentine essayist Jorge Luis Borges did just that in a memorable story called
Funes the Memorious
.
⁷
Ireneo Funes is a young man who, as a result of a head injury, has perfect recall of every moment of his life. The effect is disabling: because he sees and records in perfect detail, he can no longer categorize objects, for every new thing he sees is unique. For example, Funes is unable to recognize any individual dog as a member of a class of creature called “dogs,” by abstracting those features that all dogs have in common. Funes would have read as meaningless Ogden Nash’s prescription in
Introduction to Dogs
:

The dog is man’s best friend.

He has a tail on one end.

Up in front he has teeth.

And four legs underneath.

Because Funes sees every detail of every dog, he is unable to distinguish between those features that are specific to each dog, and those that be
long to dogs more generally. To Funes, each dog is sui generis: so distinct, one from the other, that no categorization is possible.

By the same token, Funes remembers everything that happens with perfect clarity, and is therefore unable to summarize any one day of his life by abstracting any highlights—to us, the snapshots we remember—as in doing so he is forced to relive each day in real time. Everything in his life is important, and, as a result, nothing is. Incapable of judgment, he is confined to a single room, paralyzed by self-awareness. It seems clear that while sentience has adaptive value for social creatures, one might have too much of a good thing.

All of the above rests on a single, untested assumption about the mechanics of sentience. To be sentient—to have a “theory of mind”—you must be able to imagine yourself in the drama of your own life, as if you were an actor on a stage along with imagined representations of your friends and relations.

Now, here’s the thing—if you’re all on this imaginary stage strutting your stuff,
who is the audience
? The conventional answer is that you yourself are the audience. But to picture
that
, you have in a sense to be watching yourself watch the drama, in which case there has to be another version of you watching the watcher, and yet another watching the watcher of the watcher, and so on—an infinite hall of mirrors. In the mind’s theater the watchers come and go, toward
absurdam
,
reductio
.

In
Consciousness Explained
, philosopher Daniel Dennett shows that this image of a mental theater might make a pleasing metaphor, but it is almost certainly not how the mind works. The philosopher René Descartes imagined that the “soul,” or in our terms our sense of “self,” was located in a physical part of the brain (he chose the pineal gland), but no evidence has ever come to light that any physical part of the brain corresponds with this so-called Cartesian theater. There is no central command center, like the bridge of a ship through which lots of little people look out through our eyes as windows, surveying the world and acting on information received. In terms of actual anatomy, rather than metaphor, there is no single part of the brain that processes all incoming sensory information, integrates it, mulls it over, and then instructs the appropriate responses.

Sensory information does come in, and is processed by various parts of the brain—but the processing is piecemeal, done by several different parts of the brain. Eventually, responses are formed, but again, not in any straightforward way that depends on the inputs. Indeed, the as
sumption even by trained neuroscientists and philosophers that there must, somewhere, be something akin to the Cartesian theater has led to all sorts of seemingly anomalous research results, perhaps most notably the initiation of a motor action before the subject is “conscious” of taking that action—a result that has led to all sorts of questions about free will.
⁸
The simpler solution—but somehow the harder one to take—is that there is no single center of consciousness. There is no Cartesian theater, no command center, no captain’s bridge. Sentience is an illusion, a kind of running commentary kludged together after the fact, by and for the benefit of lots of different parts of the brain at once. And the brain is easily fooled.

I am sure you’ve had dreams in which you are involved in epic dramas, dreams with plots that seem to take a great deal of time to unfold, but that end with some tumultuous noise. You awake and find that the noise is your alarm clock. As you stir yourself into wakefulness, you will naturally ask yourself how your brain laid out such a complex drama so that it culminated
precisely
at the moment your alarm went off. You might say that as you know very well that your alarm is going to go off at (say) seven o’clock—so well that you often wake up at 6:59, just in time to switch it off—then your mental impresario will have started a well-timed sequence of events designed to culminate at that moment.

But that must be wrong, as there have been other occasions when long, complex dreams have ended with some disturbance caused by a sudden, external stimulus that could not have been predicted. Is your mind a time traveler? Can you see the future? Of course not—your senses respond to the stimulus, but your mind makes sense of it backward, rationalizing it after the fact, giving the illusion of the forward passage of time.

We are visual creatures, so it’s not surprising that vision has long been the playground of neurobiologists seeking to understand consciousness.
⁹
Light impinges on the retina, causes an electrochemical change in the optic nerve, creating a signal that travels along the optic nerve to the brain, eventually arriving at the part of the cerebral cortex where the signal is processed. Does this raw signal arrive at an imagined version of a movie screening room? Apparently not—the signal is processed in various ways before it gets to the cerebral cortex. What we “think” we “see” is very far from the pattern of photons that hit the retina. The “image” has been cross-referenced with other sensory data and memories of past images, adding meaning. If this weren’t the case, that
thieving scrub jay wouldn’t be able to tell the difference between its fellow jays and any other bunch of photons. This idea—that non visual inputs give meaning to a visual image—is a bugbear for researchers into artificial intelligence, who have difficulty getting a computer to recognize that when an object goes behind another object and comes out the other side, the two are in fact the same, coherent object.

What we see of the world around us is far from a detailed panorama in which everything is in focus, up and down, and from side to side, as if our eyes were cameras. We pay attention only to a small area at any time. If this seems counterintuitive, go take a look at any landscape by the photographer Ansel Adams, and ask yourself why, for all its realism, it looks weird and dreamlike. The reason is that
everything
is in focus, from the rocks in the foreground to the mountaintops in the distance. We don’t actually see the world like that.

Color is likewise tricky. Is there a fundamental quality of, say, “red” that’s “out there” in the world? Why do we interpret electromagnetic radiation in a particular range of frequencies as “red”? When you imagine a red sports car, how “red” is it in your mental picture of a sports car? If I hadn’t asked you to imagine it, would you have seen it as “red” or—perhaps—as a label you might find in a paint-by-numbers kit, that stands for “red” but isn’t actually “red” itself? If this “label” isn’t “red,” what color is it? Does it have any color at all? If it does, would you have ascribed a color to it had I not inquired about it?

Dennett argues that there isn’t any objective reality to “red,” in the same way that there isn’t a central command unit of the mind. What
is
there, instead, is a reaction that’s been honed by natural selection in which the visual system pays especial attention to the electromagnetic radiation in the particular frequency range that is characteristic of ripe fruit when seen against a background of green leaves,
¹⁰
or, as it may be—and not uncoincidentally—the swollen genitalia of potentially receptive mates. Whether we call it “red,” “borogove,” or “manxome” is immaterial, because the explanation does not require the postulation of any kind of self-conscious inner life.

Sentience, then, is a slippery customer. One might be tempted—I
am
so tempted—to say that it doesn’t exist—not, at least, as a discrete quality.

But if that is the case, how can we interpret the behavior of Clayton’s scrub jays, or indeed of any human or animal that shows a “theory of mind” or various degrees of what Robin Dunbar calls “intentionality”?

I think that whereas such behavior
appears
to show that creatures have a sense of what is going on in the minds of others, that appearance is illusory, conditioned by our own preconceptions about sentience—that it is discrete, and, moreover, that it happens in a Cartesian theater. To put it another way, we interpret the scrub jays’ behavior for what it is because we recognize that behavior in ourselves, and we attribute that behavior to a “theory of mind.” We therefore project that theory into the heads of jays, rather in the way that our minds make sense, retrospectively, of things that go bump in the night.