Intelligence in Nature Part 4

I found Arikawa"s work fascinating, but I wondered what could drive a person to spend several decades focusing on color vision in b.u.t.terflies. I asked him about it. He replied, "I am actually a color-blind person, and I have been interested in color vision processing in general. I wanted to know how the processing of color goes on in the brain and in the eyes. And I have really liked b.u.t.terflies ever since my childhood. I was raised as an insect guy. My father gave me nice insect nets and took me to places where I collected b.u.t.terflies and beetles."

Arikawa said that when he was young, he had a science book for children which stated that insects in general do not see red. This was the received scientific opinion at the time. But Arikawa knew better because he had closely observed the behavior of b.u.t.terflies in his parents" garden in Tokyo: "My mother loved flowers, and she had lots of flowers in the garden. We had huge tiger lilies and hibiscus. And I knew that these b.u.t.terflies really prefer red flowers over yellow and blue. It sounded strange to me that insects, including b.u.t.terflies, cannot see red. So that is really the first point at which I became interested in the color vision system of b.u.t.terflies."

Arikawa has studied b.u.t.terflies for his entire professional life. He made his first contribution to science as a graduate student, back in 1979, when he discovered that b.u.t.terflies have light-sensitive neurons next to their genitals. He found that they use these "eyes," or photoreceptors, for correct coupling between males and females, and that females also use them to confirm that they are correctly laying eggs.

Once Arikawa settled into his academic teaching position, he went on to prove that b.u.t.terflies have color vision including red sensitivity. I asked, "Now that you have been studying their brains and visual systems for so long, do you think they think?"

"I hope so," he replied.

"Why do you hope so?"

He laughed. After a long pause, he said slowly: "It"s probably a problem of the definition of the word think. They have to make decisions, in any case." He went on to give some examples. b.u.t.terflies have to decide which flowers to visit, taking into consideration how hungry they are and which sort of food they want. Depending on circ.u.mstances, they may want something more watery than sticky nectar. He said b.u.t.terfly decision making was not simple. He paused again. We sat in silence for a while. Then he said, "I believe that there must be some primitive form of mind in these animals, or the ability to think in things. I don"t think that a simple chain of reflexes is sufficient to explain the whole thing."

During the silence, I thought about Arikawa thinking about b.u.t.terfly thinking. This reminded me of the story by Chuang-Tzu, the presumed founder of philosophical Taoism, who dreamed he was a b.u.t.terfly, and then no longer knew, when he awoke, whether he was Chuang-Tzu who had dreamed he was a b.u.t.terfly, or a b.u.t.terfly dreaming he was Chuang-Tzu. I asked Arikawa if anybody had studied b.u.t.terfly dreaming, or brain states a.s.sociated with dreams known as rapid eye movement (REM). He said that such studies could not be carried out because b.u.t.terfly eyes do not move, as they are fixed to the head capsule. "Eye movement means head movement. There could be some head movement when they are sleeping, but we actually do not have a clear definition of their sleep yet. At night, they are quiet, they do not move, and they hang under leaves, so they look like they are sleeping, but I don"t know."

Arikawa was quick to point to the limits of his knowledge. He also used words carefully, even though English is not his mother tongue. His approach to the practice of science had a well-rounded feel to it. This seemed appropriate as we were sitting in the Graduate School for Integrated Science, a university department where students learn a combination of physics, chemistry, biology, and mathematics, in order to develop the ability to produce interdisciplinary work.

True interdisciplinary approaches in science are rare. There was something about the work of j.a.panese scientists that seemed mature in this regard. I asked Arikawa what made j.a.panese science special. At first, he answered with modesty, denying that j.a.pan has any more qualities than Western countries when it comes to interdisciplinary approaches. But I knew that showing modesty is traditionally considered a virtue in j.a.pan, even when one is more experienced and knowledgeable than others. According to one j.a.panese saying, "A clever hawk conceals its talons," meaning to say that truly competent people do not make a show of their abilities.

I insisted on the wizardry of much j.a.panese technology and said it showed that something special was going on in j.a.panese laboratories. He laughed and said, "I know too much about this country. So it"s very difficult for me to say what is particularly j.a.panese in comparison to other nations. But one thing I can say is that we do not hesitate to break old things. The main part of j.a.pan was totally destroyed during the last war. We discarded things and imported many new things." He said he sometimes felt sad for the j.a.panese when he went to Europe and saw how people still live in very old buildings. He also said that the fact that most j.a.panese people do not live in old buildings gave them the advantage of "not being trapped in old cultures."

In deliberate reference to b.u.t.terflies, I asked whether it was fair to say that j.a.panese people like metamorphosis. He laughed and said, "In some sense, yes. We were forced to metamorphose, by the war, and also by the natural environment, because we have plenty of volcanoes, and we have typhoons and earthquakes which destroy everything. So our old buildings can simply not survive because of nature."

j.a.pan, a volcanic archipelago situated next to a major seabed fault, is one of the most seismically active regions of the world. Huge tidal waves, known as tsunami, often accompany the earthquakes. Hundreds of earthquakes occur every year in j.a.pan. Nature here is strong and uncontrollable. It smashes cities, floods them, blows them down. G.o.dzilla, the monster that arises from the deep sea and comes to destroy Tokyo, simply incarnates the forces of nature. The j.a.panese are used to rebuilding their world. And in Arikawa"s view, this enhances their capacity to innovate.

The typhoon was causing the window of his office to shake. Turning to the future, I asked Arikawa if his work had implications for robotics. "Of course," he said, "we supply our data to robotics people, but I myself do not contribute to it directly." This prompted me to ask what he thought about the scientific view of animals as machines. Referring to Descartes, I asked whether he saw b.u.t.terflies as machines.

"Hmmm," he said. "The materials which make up the b.u.t.terfly body are quite different from those of a machine. Our bodies are also machines in some sense. So we have to know that. Our minds, and the minds of b.u.t.terflies if they exist, are produced by the activity of brains. And I think that our emotions, or our thinking, all emerge from the activity of brains. So if we say that the brain is a biological machine, then b.u.t.terflies are like machines."

"And we are, too?" I asked.

"We are, too. But our body is nothing like any presently existing machine, like computers or copying machines, or cars and airplanes. No, there is some fundamental difference. Yet I think it is also continuous, with no clear border between our system and machines. I don"t know if we can really reproduce animals by manufacturing pieces of stuff, but we biologists do want to explain how our mind is constructed, or produced, on the basis of brain activity. At least I have been trying to understand that."

I asked how long he thought it would take people working on robotics to build a b.u.t.terfly, complete with sophisticated color vision and intricate neurology. "The problem is that they are not aiming at producing b.u.t.terflies, or living stuff as is," he replied. "They want to extract certain functions from animals to use for human life. If they really tried to make this animal, for fun"" He paused. ""well, one hundred years."

A century to make a b.u.t.terfly! Arikawa was clearly confident in the power of science. I had difficulty believing it. But I thought that if anybody was going to manage to build a b.u.t.terfly, he or she might well be j.a.panese. As British designer Andrew Davey recently remarked:, "The miniaturization of form twinned with the maximization of function is a j.a.panese specialty. It is a hallmark of j.a.panese design."

ARIKAWA OFFERED TO SHOW US some living b.u.t.terflies. We went downstairs and left the building. Outside, the rain was abating, though the winds were still strong. We got into his car and drove a short distance to his laboratory situated in a prefabricated single-story building. This time, we took off our shoes and put on slippers in the entrance. Arikawa showed us around the sophisticated machines that measure the spectral sensitivities of b.u.t.terfly eyes. Such research requires stripping the wings from b.u.t.terflies, tying the living insects to an apparatus, and inserting microelectrodes into their eyes. I asked Arikawa if he thought b.u.t.terflies feel pain.

"I don"t think so," he replied, "because they do not change behaviors when they have an injury on the eye; they do not do anything. So there is no clear sign that they are really feeling pain. At least, when you put a hole in the cornea, or break wings"b.u.t.terflies often have broken wings"it"s perfectly fine."

I was left with doubts on this subject, remembering what Martin Giurfa had told me about bee nervous systems secreting opioids, presumably to induce a.n.a.lgesia. But I decided not to press the point. For the moment, invertebrate rights are not high on many agendas.

We walked into another room where six graduate students were working away on computers. They said nothing and concentrated on their work. Arikawa went over to a netted box containing several yellow swallowtail b.u.t.terflies and some vegetation. He grasped one around its thorax between his thumb and index finger and held it out for us to see. It had intricate and beautiful patterns on its wings.

Then Arikawa showed us some adult silkworms. These peculiar animals are moths that have been cultivated for their capacity to produce silk when they are in their larval stage. Once the males become adults, all they do is remain immobile until they smell the pheromones released by females; then they copulate. The females lay eggs. Adult silkworms never eat. They copulate, lay eggs, and die. That"s all. Arikawa placed four male silkworms on a brown piece of paper. They looked like white moths with stubby wings. They did not move at all. But when he sprayed them with a vial containing female pheromones, they buzzed into action, beating their wings and moving around in circles on the paper.

Arikawa said the silkworms had been given to him the previous day by a colleague with whom he had co-taught a public science cla.s.s. I asked if he enjoyed communicating with the general public. He replied that partic.i.p.ating in exercises of democratic science came with his job, and that he liked stimulating people"s interest in moths and b.u.t.terflies. I asked how he felt about science dealing increasingly with money, rather than free knowledge for people.

"Yes, that"s sad," he said. "I would say the purpose of living is to entertain ourselves, to enjoy life. So the question is: How can we enjoy life, or do what makes us happy? Making money is one of these things, so it"s important, and it makes life very convenient, by using cars and such items. But I want to put on the same list of what entertains people, enjoying music, or reading novels to stimulate your brain. And science must be regarded as music, as an important piece of social entertainment for human life. That"s why I like democratic activity."

Later that afternoon, Beatrice and I made our way back to Tokyo. The typhoon was coming to an end. The rains had ceased. Hundreds of broken plastic umbrellas lay strewn around the waste bins in front of s.h.i.+njuku subway station. As we walked around town, the setting sun burst through an opening in the clouds and illuminated the city sky in pink and purple.

At one point we went into a store and admired the sophistication of the latest electronic gadgets. Several lifelike mechanical animals caught my attention, in particular a small green bird that chirped different melodies when the photosensitive cell on its chest was stimulated. When it sang, it moved its beak, shook its head and wagged its tail. I thought about b.u.t.terflies, with photoreceptors on their tails. And Kentaro Arikawa"s words came to mind: "There is no clear border between ourselves and machines." b.u.t.terflies see better than we do in some respects, though their brains are mere specks two millimeters in size. Their tiny brains can even adjust their interpretation of colors in function of light. Fancy circuitry in the b.u.t.terfly brain must be involved, but for the moment its details remain unknown.

b.u.t.terflies are transformers as they metamorphose from worm into winged insect in the pupa. People in j.a.pan are transformers, pushed by volcanoes and history to innovate and renew themselves. Shamans are transformers, changing into animals in their minds. Every living creature is a transformer, the result of a long series of transformations through evolution, which is ongoing. Every living cell is literally a transformer, transforming charges between the outside and inside of its membrane. Life itself is a transformer; it diversifies, unfolds, and morphs, and takes on as many incarnated forms as possible. And machines that act like animals are transformers, halfway between machines and living beings.

Kentaro Arikawa said there are no clear borders between ourselves and machines. He said this with complete serenity and without regrets. We ourselves are the products of the machines that are our bodies and brains, he said"without regrets, because machines can be beautiful, and have even started acting like biological creatures. As I thought about this point of view, a reformulation of Descartes" dictum came to mind: "I think, therefore I am a machine." But I did not agree.

Chapter 10.

MYSTERY JELLY.

After traveling to j.a.pan, I began searching for nature"s chi-sei, or capacity to know"rather than intelligence. I wanted to know how nature knows.

Bees handle abstract concepts, slime molds solve mazes, and dodder plants gauge the world around them. These species demonstrate a capacity to know, but they do not speak in human tongues and cannot tell us about their knowledge. Their capacity to know remains elusive. Humans, on the other hand, are good at talking. And we are also a natural species. h.o.m.o sapiens sapiens has a brain remarkably similar to those of other mammals. In fact the human brain has the same basic architecture as all vertebrate brains. In the absence of barriers between humans and other species, it dawned on me that I could approach nature"s capacity to know by considering how humans know.

Descartes could place only one thing above doubt, namely his own existence as a thinking subject. "I think, therefore I am," he wrote. This prudent stance inspired me to focus on how I know.

I thought of myself as an organism. The word comes from the Greek organon, meaning tool. As an organism, I am a kind of tool. And I have organs, which are also kinds of tools. My heart pumps, my kidneys filter, my hands grasp and look like tools. But does this mean that humans are machines?

Descartes thought so. He described the human body as a machine made of separate mechanical parts. He compared nerves, muscles, and tendons to rubber tubing. Writing in the mid"seventeenth century, he likened lungs to windmills and described the nervous system as a network of fine nets that starts in the brain and spreads from there to the rest of the body. In his book The Treatise of Man, he wrote: "All the functions I have attributed to this machine, such as the digestion of meat, the beating of the heart and arteries, the nourishment and growth of the members, respiration, waking and sleeping, the reception by the external sense organs of light, sounds, smells, tastes, heat, and all other such qualities, the imprinting of the ideas of these qualities in the organ of common sense and imagination, the retention or imprint of these ideas in the memory"follow naturally in this machine entirely from the disposition of the organs"no more nor less than do the movements of a clock or other automaton, from the arrangement of its counterweights and wheels."

I mulled this over and went running in the woods near my home. Autumn colors, yellow and red, were blending in with the greenery. I visualized myself as a kind of machine"a b.u.t.terfly machine moving through the landscape, perceiving colors through my eyes. I jumped over fallen trunks and branches strewn across the path. I knew my eyes had fewer photoreceptors than those of a b.u.t.terfly, but I could see well enough to run through the forest without falling down. I knew of no human-made machine capable of doing this.

Since Descartes, the mechanical view of living beings including humans has enjoyed popularity among scientists and philosophers. But living beings differ in fundamental ways from the mechanical devices built to date. We can reproduce ourselves and we can grow and transform ourselves"while computers, toasters, and automobiles are incapable of such feats. When my parents" ovum and sperm fused, they formed a single cell. This fertilized egg gradually grew into a human-shaped embryo through a series of duplications, at first into undifferentiated and nonspecialized cells, then into cells as diverse as neurons, blood cells, and skin cells. As my embryo transformed itself in this way, I came into being, a transformer from the get-go. Now, decades later, my body continues to repair its wounds and still becomes more resistant as I use it. In all of this, I am like countless other organisms and unlike the overwhelming majority of human-built devices.

True, humans are starting to design technologies that emulate the ways of nature. But so far, among all the devices made of metal alloys, silicone, plastic, and rubber, there is nothing really equivalent to living beings made of living cells. Each individual cell in a body is alive. Living cells are themselves creatures with a life cycle, and they must look after their own survival by adapting to the circ.u.mstances they encounter. This vital aspect of all biological creatures is absent in machines such as computers, the elementary particles of which are inert materials. Computers may now greatly exceed the computational capacities of humans. And they may now be endowed with "artificial intelligence," meaning to say that they can be programmed to do things that would otherwise require intelligence if done by a living organism. But this does not mean that machines are alive in the biological sense. It means that they can be made to exhibit certain characteristics usually a.s.sociated with life.

Some computer programs can generate informational ent.i.ties that reproduce, evolve, and mutate, all the while competing with one another. These forms of "artificial life" function in ways comparable to living organisms. But computer programs written with sequences of ones and zeros (representing voltage on and off) cannot move around and feed themselves in the material world, and are not equivalent to living beings like bacteria, birds, and humans.

I do not know if machines know, but my impression is that I do. How does knowledge come to me? My knowing self seems to me to be lodged inside my head, behind the eyes, slightly above nostril level. And contemporary science confirms that a large part of human knowledge, including experience, sensation, and thought, is mediated by our brains.

The human brain has the consistency of jelly. According to some estimates, it contains about one hundred billion nerve cells, or neurons. Each neuron can form thousands of links with other neurons. This means that the human brain has many times more connections than stars in our galaxy. How such a complex network takes shape in an organism that originates as a single cell defies current understanding.

Scientists estimate that a cubic millimeter of the brain"s cortex"a sphere small enough to fit inside this o"contains over two miles of connecting neural "wire" (or the extensions of neurons known as axons). I tried forming an image of this in my mind but failed repeatedly. I found this difficulty was compounded by knowing that I was using my own brain to consider the matter. Conducting an inquiry with the very object of inquiry can be tricky. The human brain can have difficulty thinking about itself.

When I look at the world around me, I see three-dimensional, color images accompanied by sensations of sound, taste, smell, and touch. These images look like they are outside my head, but they are actually a reconstruction operated by my brain. How do pictures emerge from the gelatinous matter which is my brain? How do images form inside pinkish gray jelly? The mystery is not new, and remains unsolved.

Since the 1990s, scientists have generated vast amounts of new information about the brain and mind thanks to innovations in brain-imaging techniques. Using functional magnetic resonance imaging (MRI), scientists can now peer inside the thinking, feeling brain, and see it in action. Magnetic scans work by revealing increased oxygen-rich blood flow, which occurs when a particular location of the brain is engaged in a specific task. A researcher need only put a few people into the scanner and ask them to think of an idea or behave in a given way. After subtracting the brain areas that are active in performing basic tasks, the machine depicts the brain areas critical to the task at hand as splotches of light on a screen. The neurons involved in identifying the color red, or recognizing a face, or adding a sum, or categorizing apples as fruits, light up on the screen like magic. Such research has led to a clearer understanding of the brain"s spatial organization. For instance, scientists have shown that children who learn a second language use overlapping brain areas when speaking the two languages, while those who learn the second language later in life use a distinct part of the brain for the second language. This holds true for Chinese people learning English or for Italians learning Hindi.

Brain imaging shows that most of the brain works at one time or another during the day. Though some functions require the activity of only small parts of the brain, most complex behaviors or thought patterns use many different brain areas. Thinking of an alpine landscape activates one network of brain areas, while thinking of cats lights up an entirely different network. Once the thought is over, all the activated neurons fall silent. Brain imaging reveals that each different thought lights up neurons in its own specific combination.

However stunning these results may be, pictures showing splotches of light on a screen do not explain how the brain works. Just because certain neurons are correlated with a behavior does not mean they cause it. Increased blood flow in a specific part of the brain as revealed by a magnetic scan merely indicates that active neurons, which require extra energy to do their jobs, are sucking in glucose and oxygen from the blood. This does not say much about how we experience what we experience. The fact that your neurons are using glucose and oxygen does not explain how you see an image of the words on this page.

BY OBSERVING PEOPLE with localized brain damage, scientists have long known that the human brain is divided into modules that perform separate tasks. The part of the mind that sees, hears, and thinks is often a.s.sociated with the top layer of the brain called the cerebral cortex; this includes the frontal lobes, which are involved in making plans and a.s.sessing risks, and the visual cortex at the back of the head, which processes visual information. Recent research using brain imaging has confirmed this modular understanding, showing that precise, and sometimes surprisingly small, groups of brain cells work in concert to carry out highly specialized functions.

Brain imaging has also revealed the importance of the brain"s deeper layers, known as the "emotional" brain. Most in-coming information, including what we see with our eyes, is initially processed by the deeper parts of the brain before being relayed to the upper levels. For example, visual information first goes to a small cl.u.s.ter of neurons in the center of the brain known as the thalamus, then down to the amygdala, a small almond-shaped structure that mediates instinctive fear. The information is also relayed from the thalamus up to the cortex, but by a longer, slower route. This arrangement explains how we sometimes respond to potential dangers before we become fully conscious of what they are. For example, we recoil from a snake on a forest path before we have an awareness of seeing it, because our emotional brains jolt our bodies into action. This capacity for rapid response may not be very precise"sometimes the snake is only a stick"but it provides obvious survival benefits. We are wired for survival, to a certain extent.

Magnetic brain imaging also reveals that our minds are on a kind of neural tape delay. For example, the areas of our brains involved in recognizing objects show peak activity before we ourselves recognize objects. The human brain appears to construct conscious awareness in an after-the-fact fas.h.i.+on. People perceive events about eighty milliseconds after they have occurred, just a bit longer than the blink of an eye. The brain appears to use this time lag to carry out fancy editing tricks. For example, when I snap my fingers, the sight and sound of the snap are processed in different parts of the brain and at widely different speeds, yet they seem simultaneous to me. I am never aware of what is happening now in my brain, but only of a small part of what has just happened there.

Furthermore, the brain is not limited to the skull. My gut alone contains about one hundred million neurons capable of learning, remembering, and responding to emotions, just like the larger brain in my head. These neurons form tissue networks, which line the esophagus, stomach, small intestine, and colon. The gut brain and the head brain are interconnected and work together. My body as a whole sends a constant flow of signals to my brain, and this largely influences my experience of the world. Knowledge about the world comes to me through information I get from my senses and through my body"s experiences. My body moves about in the world and verifies what I think I know.

People"s bodies sometimes know things before people themselves do. In a controlled experiment, scientists asked people to draw cards from four decks, two of which were heavily skewed with penalties. Skin measurements showed that people contemplating the bad decks began sweating more profusely before they themselves could verbalize an intuition about which decks to avoid. Such research shows that emotions are a mix of brain states and body experiences, which include increased heart rate, hormonal activity, and input from the gut brain. It also shows that the body plays a role in the reasoning process. Having a gut feeling is not just a metaphor.

We often think of emotions as mental phenomena, but many emotions require the body to play themselves out. People may feel fear in the pits of the stomachs, or love in their hearts. And when they are deprived of all bodily sensations, they have difficulty experiencing emotion; for instance, people suffering from "locked-in syndrome""which means they are so thoroughly paralyzed that they can only communicate through eye movements"report an astonis.h.i.+ng lack of fear about their condition. According to neurologist Antonio Damasio, this is because they have no way of using the body as "a theater for emotional realization."

Though the brain and body work together to know the world, the brain seems to be the key organ that people use to articulate and store their knowledge. Our brains harbor our minds and memories. But what is mind? And what is memory? Mind derives from the Old English gemynd, meaning memory or thought, and stems from the Greek mnasthai, meaning to remember. Mind and memory go together.

Most current theories say that long-term memories are determined by the ways in which neurons connect with one another. Connections between neurons are called synapses. A synapse is a gap, a small s.p.a.ce where neurons exchange chemicals known as neurotransmitters. When a neuron communicates with a neighbor, it fires an electrical impulse down its body to the synapses, where it causes the influx of charged calcium atoms; this in turn triggers the release of neurotransmitters, which squirt through the synapses over to the receiving neurons, where they set off new electrical impulses. Recent evidence suggests that synapses strengthen and even duplicate if they are used frequently, and weaken and become less efficient at transmitting charges if they are not used.

Research also reveals that all species with brains, from snails to humans, change the synaptic connections between neurons when they learn and remember. And to carry out these changes, they use the same molecules. Humans are united with other species down to the memory bank and back.

Many scientists now believe that memories are formed and stored in the brain"s pattern of synapses. As each neuron in the human brain can have up to ten thousand synapses, the overall brain can take on almost limitless configurations. Memory appears to be stored in the entire cerebral cortex and to be consolidated through synaptic change in neuronal networks. When our synaptic connections get stronger because we have just learned something, our neurons activate their DNA and synthesize fresh proteins. Scientists now suggest, mainly extrapolating from research on rat brains, that knowledge and memories are etched onto neuronal circuits in this way. Likewise, there is evidence that each time an old memory is brought to mind, the brain consolidates it by making new proteins, before putting it back into storage. It is possible for a human to experience this consolidation, for example, by learning a text by heart, then forgetting it again, then repeating the cycle several times, memorizing it in a fairly permanent way in the end.

Short-term memories, which only last up to a minute, do not appear to require protein synthesis. Neuroscientist Barry Connors describes short-term memory as "a dynamic, ephemeral process that has not yet yielded to molecular characterization."

Long-term memories have recently been a.s.sociated with the formation not only of new proteins but also of new neurons. For decades, scientists used to believe that the brains of adult animals could not change. But now they have discovered that all animals, including humans, grow new neurons throughout their adult life. And by studying the brains of adult rats, scientists have found that these new neurons are essential for at least one type of memory, fear. Research also indicates that acquiring new knowledge increases the survival of new neurons. Learning, it seems, rejuvenates the brain, from rats to humans.

Recent research on memory has made important discoveries but falls short of explaining how new proteins, strengthened synapses, and new neurons relate to precise memories we can call to mind, such as an image of the Mona Lisa"s face, or a Beatles melody, or the name of France"s capital city. After all, proteins, synapses, and neurons are not images, melodies, or names but components of the gelatinous matter that makes up our brains. The mystery remains as to how brain jelly can generate constructs such as mental images. Nevertheless, it now seems established that physical changes in the brain underlie the mental capacities of learning, remembering, and knowing.

Scientists are finding it difficult to learn how the brain learns. According to neuroscientist Joaqun Fuster, cognitive information requires the activation of "wide, overlapping, and interactive neuronal networks of the cerebral cortex" in which "any cortical neuron can be part of many networks, and thus of many precepts, memories, items of experience, or personal knowledge." And physiologist Eilon Vaadia writes: "It is widely accepted that large areas of cortex are involved in any behavioral process, and that these areas contain many modules, each consisting of groups of cells that process specific information. It is often a.s.sumed that, once the brain matures, each module and each cell fulfills one specific function. But acc.u.mulating evidence indicates that this may not be so. Instead it is likely that each cell partic.i.p.ates in several different processes. The brain is also constantly changing, and each cell"s effects may be rapidly modified. So it is essential to study a large number of neurons simultaneously to understand how cells communicate and how neuronal interactions are modified in relation to learning and behavior."

The brain is malleable by nature, otherwise we would neither learn nor know. It wires itself in different ways depending on the experiences we have and the skills we acquire. For example, brain imaging of string musicians shows that the area of cortex that governs the fingering hand is larger than that of the other hand, and that the most-used fingers take up the largest s.p.a.ce. There is also increasing evidence that the brain can reconfigure itself when impaired. Brain imaging shows that people who have regained use of a limb after a stroke in their motor cortex have learned to use many distinct parts of their brains in a coordinated fas.h.i.+on to make up for the inactivity of the damaged area. And dyslexic children can learn, by hearing sounds slowly and many times over, to change their brains and use different regions to process language. Some people can even exercise themselves out of paraplegia, because slow and patient exercise allows new parts of their brains to learn to take on the tasks no longer fulfilled by the damaged parts.

Our brains are built to soak up knowledge. They are wired for change. They are transformers. Descartes emphasized that knowing about the world involves having a first-person self. I think, therefore I am. Knowledge and self hang together. But knowing beyond doubt that I exist as a thinker of thoughts says little about the nature of "I." And since Descartes, no one has managed to explain how a conglomerate of cells turns into a self.

Having a self corresponds to most people"s most basic experience in the world. We refer to ourselves as "I" or "me," and do not doubt our own existence as such. Yet some contemporary philosophers and neuroscientists posit that the unitary "I" is actually an illusion concocted by our brains. They justify this stance by pointing out that research has failed to reveal a centralized spot in the brain where the self exists. According to this view, we are at best a bundle of selves a.s.sociated with many different brain configurations. They see the unitary self as a "chimera," an ent.i.ty "devoid of self-nature." In this view, the feeling I have of being a self is in fact a series of systems formed by billions of neurons that merely feels like a self.

Philosopher Colin McGinn points out that this argument "a.s.sumes that we know more about the brain and the self than we really do. Our current knowledge of the brain does indeed reveal no unifying physiological principle to correspond to the idea of a unified self, but that is equally interpretable as showing that our knowledge is very limited, not that there is no unified self." It does seem hasty to conclude that we ourselves do not exist.

I do not doubt that I exist. As I sit here typing these words, watching my fingers move over the keyboard, I know I am somewhere inside my body. Since the beginning of this book, I have been choosing the words. I can hear them ring in my mind before my hands type them out. I have conducted this inquiry from my point of view throughout. And you, when you read these words, you know that you are reading them. But all this does not change the fact that we still do not understand the nature of the self.

The problem may stem from a confusion of explanatory levels. The brain is the physical underpinning of the mind, but the two should not be confused.

Having a healthy brain certainly helps having a wholesome sense of self. People who have sustained brain injuries can lose their sense of self, or feel they are in the wrong body, or believe they are several people at the same time. But this does not dissipate the mystery. Though most people with healthy brains feel sure they have a self, n.o.body really knows just what a self is.

Progress so far in neuroscience has been compared to the accomplishment of the Wright brothers, who flew the first airplane"if the goal were to reach the moon. When Orville Wright first took off in 1903, he flew one hundred and twenty feet. It took sixty-six more years before humans walked on the moon. Research on the brain and mind is in its infancy.

Being gelatinous and highly malleable in its functioning, the brain is unlike any known machine. The activity of neurons, as currently understood, does not explain how we see images in our heads. We know neither who we are as knowing selves nor how the mysterious sense of self emerges in a biological organism. Understanding the human capacity to know is only just beginning. For the moment, no one really knows how mind and knowledge spring out of the gray, fleshy matter inside our skulls.

Chapter 11.

CHI-SEIAND KNOWING NATURE.

Nature uses signs, many of which escape our eyes. A sign is something that stands for something else. The DNA and RNA molecules contained in living cells can have several functions, one of which is to stand for the sequence of amino acids in proteins. DNA and RNA signs carry information according to an arbitrary system in which every "word" has three "letters." Science has only recently begun to study signs in nature.

Shamans have long said that nature uses signs and communicates. Taking their insights into consideration could improve scientists" understanding of nature.

Individual cells communicate using protein signals and other molecules to relay information to one another. Plants communicate with volatile chemicals, while b.u.t.terflies use ultraviolet signs, and dolphins use underwater sound waves. Humans communicate with language. Plants and dolphins cannot speak our language, and we have difficulty communicating with them. But this should not stop us from recognizing that many living beings spend a lot of time communicating. Information of one sort or another is constantly circulating in nature, in particular in the form of biochemical molecules. The world is streaming with signs.

Not so long ago, some people considered the use of signs a specifically human trait. But defining human specificity by listing traits that only humans possess has turned out to be a difficult exercise: Either some people do not exhibit the trait or else members of some other species do. People in Western cultures have obsessed about the difference between humans and animals. But humans are animals, and our capacities grow out of our common past with other species. So why conceive of ourselves as entirely separate from them? Why the obsession to look for the human distinction?

j.a.panese semiotician Yos.h.i.+mi Kawade wrote in 1998: "The Western mind draws a sharp boundary between the human and the rest of the world (also between the human and G.o.d); for j.a.panese, that boundary is much less clear-cut, especially between the humans and animals"for the Western mind, it is hard to recognize mind in animals, whereas for the j.a.panese mind, it is hard not to do so."

But the situation has since grown less clear-cut. Western scientists have recently generated a mountain of data demonstrating that humans have kins.h.i.+p with other living species. What may still be lacking among Westerners is a willingness to accept the consequences of this kins.h.i.+p. And Western languages may lack the appropriate concepts to think it through.

I launched into this investigation seeking to understand "intelligence in nature," but gradually realized that intelligence has so many different meanings that trying to define it does not seem intelligent. In j.a.pan I realized that the j.a.panese word chi-sei, meaning knowing-ness or recognizing-ness, provides a workable alternative.

In English, to know and to recognize are related. The verb know comes from Old English cnawan, meaning "recognize, identify." Its first definition in Webster"s Dictionary is "to apprehend immediately with the mind or with the senses; perceive directly; have direct unambiguous cognition of." A slime mold in a maze has the capacity to apprehend its situation and act on its knowledge. It can take in many different variables about the world around it and make a decision that enhances its survival. It has chi-sei. But is this knowing-ness, or recognizing-ness?

Recognizing-ness does not exist in dictionaries, whereas knowingness does. At first I thought it might be the clear concept I was looking for as an alternative to intelligence. But on closer inspection, knowingness is a.s.sociated with the adjective knowing, which the Oxford English Dictionary defines as "suggesting that one has secret knowledge" and as "(chiefly derogatory) experienced or shrewd, especially excessively or prematurely so." This was not the kind of knowingness I had in mind.

I considered know-how as a translation for chi-sei. But it means "expertise," which itself means "great skill or knowledge in a particular field." Chi-sei is about knowing how, but know-how does not mean this.

I also tried apprehension, cognizance, and understanding, but none fit the bill. Apprehension means "anxious or fearful antic.i.p.ation." Cognizance refers to "the action of taking judicial notes," or to a "distinctive mark worn by retainers of a n.o.ble house." Even an apparently simple word like understand is loaded. Its first meaning is "to perceive the intended meaning of (words, a language, or a speaker)."

I did not find an English word equivalent to chi-sei that could apply neutrally to other species. Intelligence, awareness, cognizance, and understanding were all defined in human terms. Faced with the absence of an appropriate word, I decided to import chi-sei into English, meaning "capacity to know." Yes, a j.a.panese import.

When I talked about intelligence and chi-sei with an American neuroscientist friend, Valerie Stone, she encouraged me to think in a new direction and to consider chi-sei in contrast to something like the operation of a thermostat. This device, which switches heat on when it gets too cold and off when it gets too hot, has sensors for detecting temperature and internal wiring to control its "behavior" and "decisions." By a basic definition of intelligence, such as making appropriate decisions, a thermostat appears to display "intelligence," she said. And as a thermostat appears to apprehend its immediate environment and act on that apprehension, it also appears to have a basic form of chi-sei, the capacity to know. But granting these faculties to this nonliving device rests on a fallacy. A thermostat can only interact with its environment because a human has programmed it. It has no real way of solving problems, such as "too hot" or "too cold," by itself. Behind a thermostat"s apparent "intelligence" or "capacity to know" lies human intelligence and knowledge.

There is a further difference between what slime molds and bees do and what a thermostat does. Stone also pointed out that thermostats change behavior according to a very simple mechanism that never varies, whereas organisms act flexibly. The single-celled slime mold"s behavior is interesting, she said, because it can solve new problems, using a computational mechanism we don"t understand yet. It uses much more computation than a thermostat and shows much more flexibility. And a b.u.t.terfly"s visual system can solve the problem of color constancy even in new lighting conditions. Life forms have a capacity to know, which is creative, whereas a thermostat tends not to do anything new.

Chi-sei and the flexibility that goes with it require a capacity to process information. According to Tos.h.i.+yuki Nakagaki, the scientist who showed that slime molds can solve mazes, and who introduced me to the concept of chi-sei: "The brain is an interesting object in that it is an excellent computer, but we don"t know how it functions. And we don"t know how brainless microorganisms perform information processing. In fact, what we really don"t know is the extent of the capacity of the microorganism to process information."

Scientists have begun to study information processing in brainless multicellular organisms such as plants. Plant cells relay information to one another using signals such as charged calcium atoms. Our neurons do the same. Plant cells also have their own particular signals, which tend to be relatively large and complicated proteins and RNA transcripts. These molecules swim around the plant providing information from cell to cell. Individual plant cells also appear to have a capacity to know.

So do c.o.c.kroaches. Research shows that these insects detect approaching predators by sensing minute air movements, and that they have neurons in their brains which fire at a rate that varies with the wind. Given that air movements change when a predator approaches, this sensing capacity allows c.o.c.kroaches to surmise the direction of an attack and scurry away to avoid being eaten.