Part 3 (2/2)

He asked me to explain my interest in his work. I told him that studying the knowledge of indigenous Amazonians had led me to investigate intelligence in nature. He listened, then commented on the problem Western people have with applying the concept of ”intelligence” to nature. He said it was possibly due to the influence of Christianity. I had not turned on the tape recorder yet. I asked him to pause briefly while I did so. Then he resumed and described the conditions in which he and two colleagues”one j.a.panese and one Hungarian”had published their experimental demonstration that a true slime mold can solve a maze. Nakagaki and his j.a.panese colleague did not hesitate to refer to ”intelligence” in their conclusion. But the Hungarian co-author proposed to delete the term. The two j.a.panese scientists prevailed, and the journal Nature duly published their paper containing the word intelligence. Much media attention ensued, both in j.a.pan and abroad. Nakagaki said, ”I have, in the course of my press interviews about this subject, found myself discussing with foreign reporters just what intelligence is. Whereas j.a.panese reporters were most deeply concerned with the details of just how such an organism was able to solve a maze, those from overseas tended to focus on whether or not the phenomenon represented intelligence.”

He attributed this difference to religion. ”I got the feeling that some Western people, possibly because of the influence of Christianity, may feel somewhat uncomfortable when faced with the possibility of intelligence other than human.” In j.a.pan, he said, people do not hesitate to refer to nature, and even to materials, as intelligent. ”In j.a.panese culture, we have a religion of s.h.i.+nto, which is a sort of animism. So we are likely to accept that everything has spirit, or something like that. This is quite a natural thing for me,” he said, laughing.

He got out of his swivel chair, went to the writing board, and marked the j.a.panese term for intelligence: chi-sei, in which chi means to know, to recognize, and sei means property, or character, or feature. Like knowingness, or recognizing-ness. He p.r.o.nounced it CHEE-SAY.

”Chi-sei is the term used to translate the English term intelligence. But I feel there is some difference between these two words, in their background meaning.” He wrote the word intelligence on the board: ”I feel that behind this term, there is Western Christian culture, in which intelligence is a gift from the G.o.d to humans only.” He laughed, then went to his desk and pulled out an article ent.i.tled ”Smart Behavior of True Slime Mold in a Labyrinth.” He handed it to me, saying it contained his view on the definition of intelligence.

I had already read this article by Nakagaki, in which he reflects on what the true slime mold actually does in the maze. By adjusting its body shape to occupy the shortest route between two food sources, it optimizes its intake of nutrients and its chances of survival. ”If the survival mechanism works well even in complicated and difficult situations, then the behavior seems to be smart,” Nakagaki writes. ”All biological systems must be rather smart. It is not yet known how smart the microorganisms are. In fact, (true slime mold) Physarum”s smartness may be more involved than simply maze solving because life in the wild is more complicated and difficult.”

When I first read this article, I wondered what difference Nakagaki made between intelligence and smartness. I put the question to him. ”When I use the term smart, Western people agree,” he replied, laughing. ”Recently I have only used the term smartness.”

I asked whether smartness corresponds to the j.a.panese term chi-sei. He said, ”Just a moment please” and went back to the drawing board. He seemed at ease standing up, writing out words, and drawing connections between them. He explained that in j.a.pan, people call chemical materials that have functions intelligent materials. But in English, the corresponding term is smart materials. ”I didn”t know this correspondence,” he said. ”I thought Western people used intelligent materials.” He a.s.sociated intelligence with ”spirit, or mind, or awareness, or something like that,” while smartness is ”rather neutral, or physical, or well designed.” He listed these terms on the board.

I said I understood the term smart to mean flexible and quick when referring to materials.

”Ah, okay, so this word is more appropriate for our study,” he said. ”Flexibility and adaptability.” He wrote both terms under the smartness list.

This prompted me to mention the definition of intelligence used by Anthony Trewavas when referring to plants: ”adaptively variable behavior during the lifetime of the individual.”

”Yes, yes, yes,” he said. ”All kinds of organisms have such abilities, adaptability and flexibility. This is true, I believe.” He contrasted these abilities to awareness and mind and went on to discuss information processing in biological systems. He wrote the word unconsciousness on the board and said that most information processing in humans occurs at the unconscious level. ”So awareness is the small tip of a large mountain. In this sense, all kinds of organisms have a sort of unconscious level of information processing. This ability is very high, higher than we expect.”

Nakagaki pulled out a round, plastic dish and handed it to me. It contained the original 3-by-3-centimeter maze in which he and his colleagues had tested the slime mold. It consisted of a negative of the maze cut from a plastic film and superimposed on an agar plate. As true slime molds dislike dry surfaces, they tend to crawl only on the wet, gelatinous agar plate, which the plastic film does not cover.

Then he turned to his computer and showed us some video images of the experiment. First one sees Nakagaki cutting about thirty small pieces from the growing tip of a living slime mold and placing them throughout the maze. As true slime molds move at a speed of about half an inch an hour, it takes a time-lapse camera to reveal their movements. A two-minute sequence concentrating several hours of action shows the bits of slime spreading themselves along the maze”s corridors and blending into one another. They become a single organism, one giant cell covering all available s.p.a.ce within the maze. Nakagaki then places the slime mold”s favorite food, oatmeal, at the start and end points of the maze. Waves start rippling across the yellowish body of the slime mold, emanating from around the oatmeal and splas.h.i.+ng down the maze”s corridors. The flat ma.s.s of yellow jelly that makes up the slime mold”s body begins to develop veins that run through the maze. The slime mold ends up withdrawing from blind alleys, avoiding detours, and reducing itself down to a single yellow vein connecting the two food sources by the most direct route.

After seeing these images, I asked Nakagaki if he could show us a living slime mold. He accompanied us out of his office and across the corridor into the storage room for unicellular organisms. The room itself was painted in drab yellow and contained several refrigerators. He opened one and brought out a foot-long plastic container half filled with a bright yellow slime mold. On close inspection, the giant unicellular creature had a solid texture, like mashed potatoes. Nakagaki explained that when a true slime mold lacks water, it goes into a dormant phase during which it becomes dry and can be stored almost indefinitely.

I asked how the idea of putting a true slime mold into a maze first came to him. He said that several years previously, one of his jobs was to feed the laboratory”s slime molds. He usually gave them oat flakes. One day he noticed that if he sprinkled the oat flakes randomly on top of a slime mold, it would form tubes connecting the food sources, and that the tubes were connected to one another in a such a way that the organism derived the maximum amount of nutrients in the minimum amount of time. As Nakagaki has training in mathematics, he began trying ”to clarify the smartness of that tube network.” He said the point of the maze was to test the expression of that smartness.

We headed back to his office, and he explained that the single-celled slime has the capacity to turn itself into an efficient network of tubes. This is impressive considering that humans have difficulty deducing the shortest connections among just a few locations. He sketched a few examples of tube networks set up by true slime molds. The writing board was starting to look like an evolving road map. He erased old parts and drew over them.

Nakagaki said that a true slime mold turns into an efficient tubing network by contracting and relaxing its body in waves. By varying the rhythm of the contractions, it can move its gelatinous contents either inward or outward. For example, when food is sprinkled on a slime mold, its contractions change drastically. These contraction patterns are self-organized, as there are no leaders or conductors in the protoplasm; rather, parts of the h.o.m.ogeneous slime interact in a synchronized way. Just how this kind of self-organization works is a serious question for mathematics and theoretical physics, according to Nakagaki. ”So in this organism, there is no nervous system, no brain, but it has the ability to solve difficult mathematical problems. But the way of computation of this organism is quite unknown,” he said.

The rhythmic contractions that ripple across the slime mold and allow it to move are regulated by a complex mechanism that has yet to be elucidated. So far, researchers have determined that different substances partic.i.p.ate in the regulation of these contractions, including charged atoms of calcium, which oscillate. These biochemical oscillators may give rise to waves that propagate through the slime mold”s body and that seem to lead to the development of tubes. But the details remain obscure. Nakagaki thinks the way forward in understanding how a slime mold does what it does is to proceed with mathematical modeling of its behavior, and in particular of its contractions. Understanding what happens in the contraction patterns from a mathematical point of view would allow one to understand how it self-organizes its movements. This, he said, was the main subject of his current research.

I asked how his work had been received by the international scientific community. He said that he goes to international conferences on applied mathematics and physics, and that researchers in these fields have welcomed his work. But he had hardly received any responses from biologists. I found this surprising and asked why he thought it was so. ”Recent biologists work on molecular biology,” he said. ”To such people, it does not matter how the biological system works. They are, in principle, only chemists.” He laughed. ”But biologists in the field investigating the behavior of animals like my results.”

My impression was that an increasing number of scientists were opening up to the idea of intelligence in nature. I asked Nakagaki whether he agreed. He replied that after publis.h.i.+ng his research on maze solving by the slime mold, he had become more careful in his use of the term intelligence. Its definition seemed to change from one person to the next, and some critics argued that the slime mold”s behavior could not be considered intelligent because they did not believe it solved the maze by conscious decision.

I asked how those critics could be sure that a slime mold is not conscious.

”I don”t know,” he replied. ”But, I”ll say it again, consciousness is the small tip of a large mountain.” He considered consciousness to be a useful term to refer to self-awareness, as when humans observe themselves observing themselves.

I doubted that introducing concepts of consciousness and self would cast much light on intelligence, if only because the workings of consciousness and the nature of self remain obscure. Nevertheless, Nakagaki”s research showed that the slime mold computes. And many consider computation to be among humanity”s finest intellectual achievements. I asked him about this.

”The slime mold computes,” he replied, ”but this process corresponds to the unconscious level, I think.” He stood up and wrote unconscious level on the board. In his view, most internal information processing takes place on this level, even among human beings. ”I doubt anyone could explain how it is their body maintains balance when they ride a bicycle. While we are riding, our body just naturally performs the calculations required to solve the equation. It would be quite difficult for us to clearly define these on the conscious level, and were one able to do so and publish the method employed, it would undoubtedly be an important contribution to the scientific literature.” For Nakagaki, all living organisms have unconscious information-processing mechanisms. Whether this const.i.tutes intelligence is a matter of debate. His research aims at clarifying these mechanisms, he said, if possible at a material level, in order to find out whether or not single-celled creatures possess intelligence. In this effort, he considers the slime mold to be an ideal subject.

Having spent the afternoon talking, we went out to dinner. Nakagaki invited along his wife, Yuka, and their three-year-old son, Gen-ichiro. We went to a restaurant specializing in traditional j.a.panese cooking and sat together around a low table in a room part.i.tioned off from others by bamboo walls. Yuka had worked as a travel agent for ten years. She spoke with enthusiasm, and in fluent English, about South Korea, one of her favorite countries to visit. Gen-ichiro played quietly with his mother”s cell phone. Though we drank a number of gla.s.ses of sake, I still had some questions. In particular, I wanted to know what Nakagaki thought about the importance of studying intelligence in nature. He replied that it is ”one of the most important questions in science.”

I agreed but said that, until recently, most scientists had held the opinion that nature lacks intelligence.

”So, this opinion is wrong. This is obvious,” he said. ”Most scientists are surely ill informed on this question. They only think about their own subject. Apart from their own subject, they are ill informed.”

He looked straight at me from across the table and added, ”You think about intelligence in nature, and you investigate many cases of research describing intelligence in nature. So you know more about this intelligence than I do. So you are the specialist on the problem of intelligence in nature. Whether you are a scientist or not does not matter. Since the times of Greek philosophy, we have basic questions on the mind and intelligence. Archimedes and Pythagoras thought about these serious problems. Descartes also thought about them. In this time, only a few people think about this serious problem. We do not have to share the opinions of most scientists.”

After the discussion with Nakagaki, I thought about the concept of chi-sei. He said that j.a.panese people did not question applying this term to the maze-solving slime mold. This was perhaps a concept I needed. Intelligence had been defined in too many different ways and had become a loaded word. And smartness commonly means cleanliness, tidiness, and elegance, which weakened its pertinence to my investigation. When a true slime mold solves a maze, it demonstrates a capacity to recognize its situation, to know. And if a true slime mold has chi-sei, what living ent.i.ty does not?

Chapter 9.

j.a.pANESE b.u.t.tERFLY MACHINES.

After hiking up a smoking volcano near Sapporo, Beatrice and I headed south to Kyoto, the historical center of j.a.panese culture. Kyoto is hot and muggy in the summer. It also has two thousand temples. We spent several days seeing the sights. We walked along the Path of Philosophy, which follows a ca.n.a.l lined with cherry trees. We visited the Golden Temple Kinkaku-ji in the rain. We strolled through manicured gardens with moss carpets and ponds filled with sacred carp. One sign with an English translation posted at the entrance of a temple explained that Zen gardens are ”compressed nature.” Another sign above a small exhibit of moss samples stated: ”Very Important Moss (like VIP).” Paying attention to details in nature appeared to be a j.a.panese talent.

We caught a train from Kyoto to Tokyo and settled into a small hotel downtown. The sheer size of Tokyo takes getting used to. No sooner had we found our bearings than the first typhoon of the season blew in. Dark clouds filled the sky, and gales of wind blasted down the avenues. Almost horizontal sheets of rain poured down. People in the streets braced themselves and walked with their umbrellas directed against the winds.

The next day, the typhoon was still raging, and we traveled to Yokohama, the country”s second biggest city, which now forms an uninterrupted megalopolis with Tokyo. I had an appointment at the University of Yokohama City with Kentaro Arikawa, a professor who has been studying b.u.t.terfly neurology for twenty-five years. Arikawa is the scientist who discovered that b.u.t.terflies have color vision, and that their tiny brains contain sophisticated visual systems. He also discovered that b.u.t.terflies have eyes on their genitals.

The Tokyo subway system is mainly signposted in j.a.panese, and labyrinthine. We ended up finding the over-ground line to Yokohama, which we rode for an hour through an unending urban landscape. The train shook from the storm raging all around us. Once we reached our final destination, I called Kentaro Arikawa from a public phone outside the station, as he had instructed me to. A few minutes later, he appeared driving a gray car and flashed his lights in our direction. We were easy to recognize as the only gaijin, or foreigners, in the vicinity. We rushed through the downpour and got into his car as quickly as possible. We shook hands, then Arikawa drove off saying that we did not have far to go.

I sat in the front seat and wiped the rain from my face. Arikawa was a lanky man with short black hair, wire-rimmed gla.s.ses, and a kind, gentle face. He was in his mid-forties. He wore a a short-sleeved s.h.i.+rt, dark pants, leather shoes, and a big watch that looked suited to underwater diving. After a short drive we reached the campus of Yokohama City University and pulled up in front of the Graduate School of Integrated Science, where Arikawa teaches and conducts research. As we dashed from the car to the main entrance, I asked him what b.u.t.terflies do during typhoons. ”They hide in holes in trees,” he said, ”or under leaves.”

This time we did not take off our shoes. We walked over to the elevator, went up to the fifth floor, and proceeded into Arikawa”s office. He invited us to sit around a comfortable table and offered to make some tea. I explained my interest in his work by describing my investigation and saying I saw clear indications of intelligence on nearly all levels of nature, including in plants.

”I don”t know much about plants,” he said, ”but our intelligence must have originated from animals which were our ancestors. So intelligence, the mechanism of making decisions, must exist in present-day animals. And as you say, it is widespread, even in b.u.t.terflies.” He described the work he and his colleagues are conducting, looking at the capacity of b.u.t.terflies to see colors: ”We have already found an enormous complexity in the eye. And of course we are looking at conscious behavior, and we showed that they can clearly see colors and have color constancy.”

Arikawa explained color constancy by giving the example of a human observer who sees a red apple as red in both suns.h.i.+ne and regular room light, though the spectral contents of sun and room light are very different; in such a case, the subjective experience of red remains the same, because the observer”s brain adjusts its perception of the wavelengths reaching the eyes. This is color constancy. It turns out that the microbrains of b.u.t.terflies are also capable of this feat.

Arikawa pulled out a black page showing a series of colored patches and began explaining how he and several colleagues had demonstrated that j.a.panese yellow swallowtail b.u.t.terflies have color vision and color constancy. The scientists trained the b.u.t.terflies to feed on sugared water placed on a patch of a particular color in a cage set in the laboratory. Then they presented the b.u.t.terflies with the training color randomly positioned within an array of patches and devoid of sugared water. The b.u.t.terflies selected the training color reliably among different colors, including a variety of shades of gray. They also selected it under different-colored lights, showing color constancy. b.u.t.terflies must be able to see colors in order to recognize suitable flowers for feeding in the field. They use color information to collect food. And because food must be food, under direct suns.h.i.+ne or in the woods or anywhere else, color constancy is important to b.u.t.terflies.

Arikawa and his colleagues also demonstrated in the course of their studies that the retina of the swallowtail b.u.t.terfly has at least five different types of spectral receptor: ultraviolet, violet, blue, green, and red. They recently found a sixth receptor, which is broadband, and probably works as a general luminosity detector. In comparison, humans have only three types of spectral receptors: red, green, and blue. Arikawa and his colleagues concluded: ”The extremely richly endowed visual system of b.u.t.terflies evidently provides these animals with a versatile information-processing apparatus.”

Astonis.h.i.+ngly, the tiny brain of a b.u.t.terfly is equipped with a system of color vision that is superior in some respects to our own.

Ultraviolet photoreceptors serve several purposes. They enable b.u.t.terflies to see flowers that have pigmented ultraviolet spots indicative of nectar and pollen within. They also allow male b.u.t.terflies to detect the distinctive ultraviolet stripes on the hind wings of female b.u.t.terflies, which facilitates courts.h.i.+p and mating. Sometimes nature uses signs that human eyes cannot detect.

b.u.t.terfly visual systems develop during metamorphosis, when young b.u.t.terflies are still full-grown caterpillars undergoing self-transformation in the pupa. While caterpillars have six simple eyes on each side of the head, b.u.t.terflies develop an additional pair of large, compound eyes. The simple eyes of caterpillars have only three kinds of photoreceptors, while the compound eyes of b.u.t.terflies have twice as many. b.u.t.terflies are transformers. They do not sprout just wings in the pupa but brand-new eyes as well.

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