Thumbs, Toes, and Tears Read online

  Experimental psychologist David Premack once imagined two of our ancestors squatting alongside a fire with one of them saying to the other, “Beware of the short beast whose front hoof Bob cracked when, having forgotten his own spear back at camp, he got in a glancing blow with the dull spear he borrowed from Jack.”

  Premack was actually using this as an example of language being “an embarrassment for evolutionary theory” because he could never imagine why evolution would have created such a complex capability. But cognitive scientist Steven Pinker remarked that Premack’s complaint reminded him of the Yiddish expression “What’s the matter? Is the bride too beautiful?”

  Pinker argues that recursion is absolutely crucial to language and the unique ways in which humans think and express themselves. He says there can be no debate that it is built into the human brain. Communication doesn’t have to be tortuous and convoluted, as in Premack’s example; it can simply transmit information in a precise pattern and order that clarifies what we mean. At the very least it would have been a tool that vastly improved the chances of survival for any creature who happened to be endowed with it.

  “It [recursion] makes the difference whether a far-off region is reached by taking the trail that is in front of the larger tree or the trail that the large tree is in front of,” says Pinker. “It makes a difference whether that region has animals that you can eat or animals that can eat you. It makes a difference whether it has fruit that is ripe or fruit that was ripe or fruit that will be ripe. It makes a difference whether you get there if you walk for three days or whether you can get there and walk for three days.”7

  There are other simple forms of recursion that make the point. “Joe, who is very angry, will see you now” not only tells you Joe will see you now, which is the main thought, but also explains the state of mind he is in, which, even though secondary in this sentence, nevertheless provides crucial information. Of course, you could also turn the sentences around. “Joe is angry even though he is going to see you now.” The hierarchy of the expressed ideas conveys very different information about Joe’s state of mind and, most importantly, its effect on you.

  The precise expression of the thoughts we shuffle in our minds has other uses beyond giving clear directions, useful as they are. Where language proves its real worth is in the way we use it with one another because it is that interaction that shapes our relationships. In this may lie the secret of its power, and ultimately the reason why it seemed to blossom out of nowhere.

  …

  An odd thing about our ability to create, shift, and prioritize symbols is that it requires that we be self-aware. Why? The rise of language goes hand-in-hand with the rise of consciousness. The terms “self-aware” and “conscious” are so normal they tend to be almost meaningless to us because we take this state of mind for granted. But we shouldn’t, because it is rare outside of our species and it is essential to being human. It requires that we perceive that we have a “self” that is distinct from others and the rest of the world. If we could not make this distinction, we could not purposefully make a tool or get up off of a chair and walk across a room to shake someone’s hand because we would not truly be aware that we are different from the chair or the room or the person across the room. Nor could we consciously manipulate thoughts the way we manipulate objects, because to physically and mentally manipulate anything—on purpose—requires us to be aware that there is the manipulated and the manipulator.

  Our self-awareness begins in a very concrete way with the knowledge that we all have bodies—the most direct indication that we exist. On the most basic level this is the way we draw the line that separates our selves and the rest of the world. Neurologist Oliver Sacks makes this point about as well as it can be made with a story about one of his earliest experiences as a medical student. One evening a nurse called him to a hospital room where he found a patient lying on the floor beside his bed, gazing appalled and disgusted at his own leg. Sacks asked the young man if he could help him get back into bed, but he kept shaking his head no as he continued to stare horrified at his leg.

  There was nothing wrong with the leg so far as Sacks could see, and he couldn’t understand why the man was so upset, so he asked him what was the matter. The patient told him he had been admitted to the hospital earlier in the day for tests because his left leg felt “lazy.” At about dusk he fell asleep and then later woke up to find, to his horror and disgust, a severed leg in his bed with him! He couldn’t imagine where the thing had come from. After inspecting it, he told Sacks, he picked the leg up and struggled to throw it out of the bed, but somehow when he did he had gone with it, and now, as he sat on the floor, the limb had become attached to him.

  “Look at it!” he yelled at Sacks. “Have you ever seen such a creepy, horrible thing?” He then seized it with both hands and tried with all his might to tear it off. When that didn’t work, he began to punch it. Sacks, who was now squatting beside the man on the floor, suggested he not do that.

  “And why not?” asked the man.

  “Because it’s your leg.”

  This absolutely stunned the patient. He couldn’t believe it. He couldn’t because he was thoroughly convinced the leg was not attached to him. So finally Sacks asked him, “If this—this thing—is not your left leg, then where is your own left leg?”

  The man thought about that. “I don’t know,” he finally answered. “I have no idea. It’s disappeared. It’s gone. It’s nowhere to be found.”8

  Amazing as this story is, it is true that people do sometimes lose track of themselves or a sense of themselves or a part of themselves. Somehow the lines between them and the rest of the world disappear. In this case it turns out the patient was suffering from a disease known as Pötzl’s syndrome or optic-kinesthetic allesthesia. It is a form of dissociation from one’s self, a cousin to diseases like multiple personalities syndrome, in which people experience living as several distinct people or personalities, all of them inside the same body. Damage to the posterior portions of the right hemisphere of this man’s brain, which very specifically controls awareness, or gnosis, of the left leg, had slipped its moorings and caused him to literally lose a sense of himself, or at least that particular part of himself.

  Damage like this can be caused in several ways—stroke, concussion, brain tumor—any number of afflictions. Depending on the side of the brain that is damaged, Pötzl’s syndrome can affect your eyes, speech, or limbs. It could happen to any of us at any time, and it powerfully illustrates that our sense that our bodies and our “selves” are one and the same is manufactured in our brain, along with the rest of our reality. If the brain is physically damaged, our sense of self can warp or splinter or vanish. Injuries such as these reveal that the “self” is a very fragile thing that depends on how certain clusters of neurons connect, exchange hormones, and fire.9

  Keep this in mind the next morning you groggily pick up a cup of coffee and bring it to your lips. Ask yourself how you know it is you who is picking the cup up. Why don’t you think it is another hand that belongs to another person?

  This question isn’t as insane as it sounds. The simple act of drinking coffee requires that you not only have the physical ability to reach out, grasp the cup, and bring it to your mouth, it also requires that you perceive a “self” that is directing and following through on all of those actions. For you to succeed in drinking, you must have the perception, on some deep level, that you are separate and different from the world around you, and that the “you” drinking the coffee is all one piece, a unified whole, not splintered and separated. This makes you “self”-aware. It means, in fact, that upon reflection, you understand something amazing: that someone you call “you” exists.

  All of this seems obvious to most of us most of the time. “I am me,” you say. “How else can it be?” Except, as much as we take this ability to refer to our “self” for granted, in nature it is actually extremely rare, as psychologist Gordon Gallup proved in a famous series o
f experiments in the 1970s and ’80s.

  Gallup wondered if other primates besides us might be self-aware, at least in some sense. To get to the bottom of the question he conceived of a clever experiment. He anaesthetized different types of primates, including orangutans, monkeys, chimps, and gorillas, and placed an odorless but clearly visible mark on their foreheads. When they awoke, each animal was placed in front of a mirror. If it looked in the mirror and saw the mark and then touched or rubbed the mark, as opposed to reaching out and touching the mark in the image in the mirror, Gallup concluded that they understood they were seeing a reflection of themselves, as opposed to an entirely different animal. In other words, they were, on some level, self-aware.

  Monkeys failed the test. Orangutans, after a little time, didn’t. Chimps never failed and, surprisingly, gorillas mostly did (though some scientists have argued that there may be other reasons for this than a lack of simian self-awareness).10

  Having an image of your own body as your body is a prerequisite for the special brand of self-consciousness we all blithely live with each day. It means that unlike birds and possums, the green skeleton frogs of Madagascar, or my dog Jack, you are not unconsciously moving through the world, instinctively reacting to the forces around you. You are aware that you are doing these things, and you are actively and purposefully taking some control.

  Without that awareness, you would be no better off than the monkey that looks in the mirror and treats its own reflection as a total stranger. Or, in some way, you would be like the man who was unable to recognize his own leg for something other than the severed limb of a cadaver. Somehow you would miss the point that your body and you are one and the same. Your self and your environment would blend into one another.

  …

  A prerequisite of being conscious of your self is that you be conscious, period. And that raises still another perplexing mystery: How do you explain a mass of one hundred billion neurons the consistency of Jell-O weighing roughly three and a half pounds conjuring up something as miraculous as a human mind?

  After winning the Nobel Prize in 1972 for insights into the chemical intricacies of the immune system, Gerald Edelman began to tackle precisely that question.11 In 1981 he founded The Neurosciences Institute, where he assembled scores of scientists in fields from biochemistry to artificial intelligence and neuroanatomy to explore how the physical interactions of the human brain make consciousness possible.

  Edelman concluded that our brains are so deeply interconnected and have so thoroughly woven the primal parts of themselves into their more recent cerebral additions—the prefrontal cortex, for example—that consciousness emerges out of the trillions of interactions that take place at any given moment. It’s strange to think of something as singularly crucial as consciousness as an evolutionary by-product, but if Edelman is right, that’s where the evidence points.

  Neuroanatomists divide the brain into six broad sectors: the thalamus, brain stem, cerebral cortex, basal ganglia, hippocampus, and cerebellum. Edelman holds that the brain’s internal diversity and the way those diverse parts, both ancient and newly evolved, interact creates our special brand of human consciousness. A central player in Edelman’s theory of consciousness is the thalamus, which is, for want of a better term, the brain’s sensory gatekeeper. It sits—gray, oval-shaped, and dense with neurons—midway between the brain stem (which attaches the brain through your neck to the spinal cord) and the prefrontal cortex. Nothing we experience—the touch of a hand, a bright light, a smell, or the passing of a cool breeze—makes its way to the cerebral cortex without first passing through the thalamus. Its dense network of looping connections called the thalamocortical system constitutes a “meshwork” of communication lines that reach into every area of the brain.

  Without this meshwork, Edelman believes there would be no consciousness because consciousness requires that the brain be continually checking in with every far-flung sector of itself. And that is what the thalamocortical system excels at. It pulls and pools information from the basal ganglia, for example, which handle the planning and execution of complex motor skills; or the hippocampus, which specializes in shifting important short-term memories into longer-term storage; or the cerebellum, in the back of the brain, which helps coordinate and synchronize motion (but—according to recent discoveries—is also important to speech). In addition to these, the brain houses millions of clusters of neurons that perform specific functions, such as dealing with loud sounds versus soft ones, or linking smells with their origins in space.

  Each of these clusters “summarizes” or modulates the information that cascades around the brain the way the vibrating strings of a guitar modulate and interact with one another to create the sound of a strummed chord. This “summarized” signal is then returned to the feedback system, where it mixes with and changes other incoming summarized signals. The modifications never stop. Edelman likens these larger interactions to the interplay among the members of a string quartet.12 He writes,

  “Imagine a peculiar (even weird) string quartet in which each player responds by improvisation to the ideas and cues of his or her own, as well as to all of the kinds of sensory cues in the environment. Since there is no score, each player would provide his or her own characteristic tunes, but initially these tunes would not be coordinated with those of the other players. Now imagine that the bodies of the players are connected to each other by myriad, fine threads so that their actions and movements are rapidly conveyed back and forth through the signals of changing thread tensions that act simultaneously to time each player’s actions. Signals that instantaneously connect the four players would lead to a correlation of their sounds; thus more, new, cohesive, and more integrated sounds would emerge out of the otherwise independent efforts of each player. This correlative process would also alter the next action of each player, and by these means the process would be repeated but with new emergent tunes that were even more correlated. Although no conductor would instruct or coordinate the group and each player would still maintain his or her style and role, the players’ overall production would tend to be more integrated and more coordinated, and such integration would lead to a kind of mutually coherent music that each one acting alone could not produce.”13

  Edelman calls this synaptic dance “reentry” because it requires that all of the interacting information throughout the thalamocortical system keeps looping back, exiting, and then reentering. A simpler (but by no means simple) version of this happens when we look around. Research into the workings of the visual cortex—one of the better-understood areas of the brain—has revealed that separate parts of the cortex process the sensations of color, shape, and movement. None of them is managed by a central “boss,” any more than Edelman’s string quartet is guided by a conductor, or even sheets of music. Instead the visual information comes into the brain’s meshwork, interacts, and in the process of reentry creates a literal picture of the world, all of it formed by integrating disparate pieces of information, in the blink of an eye. What is more, these images appear whole and continuous even though different parts of the brain didn’t initially experience them that way. The visual cortex takes all of the signals and melds them into one seamless series of events.

  Consciousness, Edelman says, happens in a similar way. The brain handles information of all kinds, both internal and external. The raw information is modulated in areas that manage sight, sound, touch, and every other sensation. In a snap, long- and short-term memory are also consulted to see if the sensation is familiar. Meanwhile, neuromodulators that are squirted throughout the brain by the norepinephrine system to encode sensations as pleasing or terrifying or disgusting, add additional information.

  But only some experiences emerge into consciousness because still another selective, Darwinian-like process is at work.14 If the same information keeps reentering the system, then it has “survived” and is selected. It is nudging, sometimes shoving, the cerebral cortex, telling it that this information is an acc
urate representation of an experience and it should be paid attention to. The wind really must be blowing, that really is the scent of a predator, an attractive member of the opposite sex does want to mate. I am scared. I am elated. I am hurt. The strength and the timing of the information are related to how insistently it reenters the system, and the more insistently it reenters, the more likely it will emerge into conscious thought.

  The emergent nature of consciousness makes it the most extreme and dramatic example of what emergent systems can create. If we look back over evolution, all forms of life and all natural systems seemingly evolve out of behavior that looks chaotic, at least, insofar as they are never designed and created from the top down, not even when the result is something as remarkable as a self-conscious, thinking, talking primate. But the thing that makes self-consciousness really different is that for the first time it is a behavior that is aware it is behaving. This is something profoundly new in nature.

  If Gallup’s tests are any indications, self-consciousness in our ancestors arose by degree. Earlier hominids did not “abstract” in the way we do. They very likely shifted their attention and changed their behavior in reaction to their environment and conditioning the way most other primates do. If they were cold, they would try to get warm. If they heard a growl or saw a sudden movement, they turned to fight or turned tail in flight.

  But as our predecessors grew more self-aware, they would have begun to stop simply reacting to their environment and begun to purposefully shift their attention and take greater control of it. Why was the line of primates that led to the human race capable of this? Perhaps because earlier in their evolution their thumbs and hands enabled them to make tools, which required them to manipulate objects, which, in turn, required putting one thing aside while another thing was taken care of. And in time their increasingly sophisticated brains enabled them to apply the same talent to virtual, imaginary objects that existed only within their minds. But the wetware that ultimately pushed them into a being that was human was the prefrontal cortex.