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Pure Persistence of Plants: How Do They Communicate? -- Yoshiyuki Miwa

Pure Persistence of Plants

How do they communicate?

Yoshiyuki Miwa

Dr. Yoshiyuki Miwa was born in 1947 in Nagoya City, Aichi Prefecture. He graduated from the Department of Mechanical Engineering, the Faculty of Science and Engineering, Waseda University in 1971. He received Ph. D. in engineering from the Doctor Course of Graduate School of Science and Engineering, Waseda University in 1976. After working for Waseda University as a tutor, an instructor, and an assistant professor successively, Dr. Miwa was promoted to a professor of Waseda University in 1981. He has also been serving as director of the Research Institute of Projects for Food, Agricultural and Environmental Problems of Waseda University since April 2000.

His major is biomechanical engineering and the bio-information system of plants. He is currently engaged in various studies including those on "the technology for settings in joint-creation communication" and "performance robots." Dr. Miwa is the co-author of "Setting and Joint-Creation" (NTT Publishing Co., Ltd.) and "Biomechanical Engineering" (Shokabo Publishing Co., Ltd.).

Yoshiyuki Miwa

Dr. Yoshiyuki Miwa was born in 1947 in Nagoya City, Aichi Prefecture. He graduated from the Department of Mechanical Engineering, the Faculty of Science and Engineering, Waseda University in 1971. He received Ph. D. in engineering from the Doctor Course of Graduate School of Science and Engineering, Waseda University in 1976. After working for Waseda University as a tutor, an instructor, and an assistant professor successively, Dr. Miwa was promoted to a professor of Waseda University in 1981. He has also been serving as director of the Research Institute of Projects for Food, Agricultural and Environmental Problems of Waseda University since April 2000. His major is biomechanical engineering and the bio-information system of plants. He is currently engaged in various studies including those on the technology for settings in joint-creation communication and performance robots. Dr. Miwa is the co-author of "Setting and Joint-Creation" (NTT Publishing Co., Ltd.) and "Biomechanical Engineering" (Shokabo Publishing Co., Ltd.).

Mechanical engineering and plants will be linked to each other.

Objects totally foreign to each other will jointly create a new field as if they were originally adjacent to each other. Then we will see the very beginning of a new concept.

--What made you decide to study plants?

Miwa: I was originally engaged in research on materials used for machinery. About two decades ago, I had an opportunity to work on memory metals. Using this technology, and under the guidance of my mentor, Professor Nobuhiro Iguchi, and other advisors, I succeeded in developing the world's first insect-shaped microrobot, which functions without mechanical devices; it functions using only materials and an electronic circuit. The movement of this microrobot was so realistic that I began to wonder if I could devise a soft machine resembling living things. Around this time, a study group headed by Professor Hiroshi Shimizu at Tokyo University proposed the concept of bioholonics. I was mesmerized by their report that living things are creating macroscopic information that consolidates the functions of each autonomous element. For example, each individual cell of the heart vibrates on its own. But when combined together, an "interaction" takes place and all the cells start to vibrate at a uniform pace, which in turn makes the heart beat some 60 times per minute. I thought this idea was terrific; it's totally different from the conventional concept that machinery should be durable, trouble-free, and efficient. I dreamed of devising a machine that incorporates, so to speak, "biosoft" - the autonomy of living things. Meanwhile, it was also an era when mechatronics was burgeoning, and there was a lot of talk about the trend toward an information society. However, rather than information itself, I felt the life sciences held the key to this kind of society.

And these circumstances compelled me to begin studying the system of life and information (laughter); I took a leap in the dark. However, the world of living things had been totally foreign to me. So, I thought I must become more familiar with living things before anything else. Human beings or animals would have done as a subject, but I decided to study plants. The sense organs of plants are not so differentiated. And unlike animals, plants have no nervous system. I wondered how each part of a plant could exchange information with one another.

Even if the branch of a tree is snapped off, it will replicate itself appropriately, and the tree as a whole will function as usual. How can a tree itself sense that its branch has been snapped off? Are plants aware of how they look like, in the first place? Are they aware of changes in their figures? Meanwhile, the roots and stalks of plants grow, going around obstacles as if they are well aware of the obstacles; how does such a system work? For me, the study of plants is a never-failing source of interest.

For that matter, plants seem to be more flexible than animals in adapting to changes in the environment, because they don't move from one place to another like animals. By thinking this way, I came to realize that there had never been machines, robots, or information networks modeled after plants. Another point of interest is how each plant exchanges information with one another, a practice that can be referred to as "communication." Moreover, as I continued with my study, I began to think that I might as well address the subject as to what in the world plants are supposed to mean for human beings and animals.

--So, your interest is strictly centered on plants?

Miwa: How a plant connects each part of it with the whole body is still unknown. For example, the stalk of a plant grows toward the direction of light, which needs to be sensed by the root so that the balance of the whole body is maintained. The growth of plants is controlled by the flow of hormones, and plants as a whole need to share information to determine the method of this flow. However, the preparation of certain information doesn't work because there is a need to respond in real time to changes in the environment. Naturally, plants have no brains. So, the place where plants create information, that is, the source of information remains unknown. How does the whole body sense what is happening in each part of it? Where does each cell and organ position itself in the whole body? These kinds of issues are quite interesting since plants continue to grow and grow unlike animals. There should be a network through which information is transmitted and shared in a way that is different from that of the nervous network. Based on this assumption, I studied for a certain period of time on a possible linkage between this particular network and a meridian network or flow of energy.

--While there is a symbiotic relationship among plants, there also seems to be a turf battle among them?

Miwa: I've been doing experiments in fields for over the past 10 years or so, believing that I must see firsthand what is really happening in the fields; I needed to gain a clear picture of plants. In fact, I've been to many places such as the mangrove forest on Iriomote Island, the beech forest on Mt. Gassan, and the virgin forest on Mt. Fuji. Also, I've been studying the interrelationship among trees in the Plant Research Center in Atami for over the past four to five years. Furthermore, by way of comparison, I also studied the same subject with the artificial forest of Yoshino Cedar.

Specifically, we inserted electrodes into trees to record extremely subtle changes in biopotential, similar to monitoring brain waves or electrocardiograms. Biopotential is closely related to the life activities of trees. Our students designed and made a device that can measure the biopotential of over 300 tress scattered over a wide area. Students studying mechanical engineering are capable of inventing this kind of unprecedented device. I think this is one of their advantages (laughter).

Generally, natural forests are comprised of 15 to 16 different species of trees. Based on the biopotential waveform, these trees can be categorized into several groups. What is interesting is that trees belonging to the same species do not necessarily fall into the same group; a group is usually comprised of 20 to 30 trees of several species. In addition, the makeup of each group is not necessarily consistent throughout the year. The results of our study show that it changes in April, September and December, as the case may be. In other words, the formation of each group is not exclusive. And as time goes by, some trees join or leave groups they originally belonged to. So, each group is formed based on a polycentric and horizontal system; it doesn't take the form of a classified structure.

--So, it's not a unipolar makeup, is it?

Miwa: Changes in the daily and yearly biopotential of every tree show certain patterns. When trees such as camellias, aucubas and ashes are planted in pots individually, they begin to show different patterns as far as the daily biopotential waveform is concerned. I wonder how these trees created their original patterns. However that may be, in a forest where these trees share their habitats with one another, the waveform of each group begins to change. This means that a variety of waveforms will be created in a changing environment with these waveforms influencing one another. But this phenomenon is based on a certain rule. I presume that groups are formed through the sharing of settings and the restriction of individuality. As a matter of fact, there is an interactive coherency in the waveform of trees belonging to the same species.

I even have a feeling that a forest itself has a network, similar to that found in a brain. Through what kind of medium is such grouping being carried out? And through that medium, what kind of information relating to the life activities of trees is being shared? These topics are really interesting to track down. I may be stretching the point, but there may be something like "a vegetative Internet." As you know, the current communication network exchanges digitized signals based on the Shannon information; this may provide a clue to the idea of a communication network through which information on settings is exchanged. However, this kind of network alone would only materialize very fuzzy and unreliable communication (laughter).

Suppose you input a certain signal into a tree while you walk through a forest. Then the signal you input shows up on a display fixed on a tree located 100 meters away. Or, there could be a system in which you can determine your location with the assistance of trees. These are the things I want to experiment with in the immediate future.

A. What is meant by exchanging information on settings?

Miwa: The roots of plants create an extremely subtle electric field around them. It's medium is said to be calcium ions and protons. This electric field exhibits very unique characteristics. Taking the roots of plants as an example, they need to decide for themselves which direction they should grow when going around obstacles. This can be considered as a self-navigation system. In this case, there is a need for information that coordinates the action of each cell of the roots. However, roots have no nerves. Hormones could be an alternative, but they are too slow in transmitting information. So, I figured an electric field held the key. In fact, without an appropriate electric field around them, roots cannot go around obstacles properly, and the rate of their growth inevitably slows down. Moreover, electric fields around roots change in response to the stimulation of stalks and leaves by sound, that is, artificial changes in an aboveground environment.

Whatever the case may be, it is becoming clear through a series of experiments that electric fields function as, so to speak, a generable interface through which roots link themselves to an external environment. The roots of plants grow, sensing changes in a surrounding environment. So, they may be directing themselves to grow towards specific directions by creating electric fields around them.

If this hypothesis is correct, electric fields should have certain influences on the interaction of a few pieces of roots adjacent to one another. To prove this, I did an experiment on two pieces of roots, placing them side-by-side. There was actually some interaction between the electric fields of the two roots, often creating a coupling. What is interesting is that this coupling phenomenon synchronizes the rate of growth between the two roots. Since the formation of electric fields becomes extremely complex in the case of three pieces of roots adjacent to one another, it's not appropriate to make a sweeping statement here. But there was a notable tendency of two out of the three pieces to couple with each other. In this case, however, the isolated one is not irrelevant to the other two pieces. I mean the coupling situation will come undone if the isolated one is removed. I need to do more experiments to further clarify this phenomenon, but these results suggest that electric fields function as information on settings, and that those settings are shared through the interaction among roots.

In a forest, meanwhile, trees or groups of trees might be creating and sharing information through setting-based information that can be found in electric fields. Without this kind of method or mechanism, a forest itself could hardly maintain its diversity.

--From a macroscopic viewpoint, a forest as a whole forms a brain. For example, even if a part of a forest disappears from a communication network, that particular part will be rehabilitated somewhere in the forest. In other words, one part is linked to another like a chain reaction.

Miwa: I think forests are not designed to be self-complete in the first place, a feature that is quite different from ordinary mechanical systems. Suppose each tree is an actor performing on a stage called "a forest." Even if other actors, whether they are human beings or animals, join the play, the forest in its nature will never exclude but accept them. It seems that natural forests form settings, with trees jointly creating or dissolving their coherent relationship. I did the same experiment on the artificial forest of Yoshino Cedar. But on entering this forest, I realized that there was no place where I could feel at ease. It was quite different from natural forests or virgin beech forests. For that matter, I felt as if the whole forest functioned based on an exclusive logic. In fact, the results of the experiment showed that the biopotential waveforms were almost identical. The makeup of the forest tends to become increasingly uniform as thinning goes on.

I'm not sure if this is correct, but the stone garden of the Ryoanji Temple may represent spatial incompleteness that is typical of natural forests. Based on this viewpoint, I'm now reviewing the very concepts of tea-ceremony rooms and Japanese gardens. It seems to me that the spaces of these places are designed to create a vector that is heading toward completeness; this applies not only to city plans but also to machine designs. While tools can function only when they are used by human beings, they also contribute to our development. Modern automatic machinery and systems, however, do not have this particular feature. They are originally designed to be self-complete. As a result, we have no other options but to adapt ourselves to them.

--You raised a very interesting point. A certain thing becomes complete by incorporating something with it. Put differently, a variety of things can be incorporated. Communication begins with this incorporation. This is almost a definition of "communication." Something could begin from "n minus one." Plants are immobile in nature. But if forests have this feature in their spatiality, it can surely be applied to human beings. Spatiality and temporality may cross each other at this particular point.

Miwa: I think spatiality and totality are similar to each other in concept. They can be referred to as "a setting." It's very interesting to know how they are expressed and shared between each other. It's also a matter of how they position themselves in a certain setting. The cells comprising a root know what they are supposed to do because they know their locations in the root.

I recently performed an interesting experiment using a wheelchair. Specifically, through a head-mount display, a person pushing a wheelchair sees what the other person sitting on the wheelchair is looking at. And the former pushes the wheelchair toward a designated direction. It's a kind of experiment where a person tries to accomplish something through the hands of another. Maneuvering the wheelchair based on the images on the display is not easy. In fact, the person pushing the wheelchair was not able to properly negotiate around obstacles. This means that visual perception and motion associated with it are not sufficient to maneuver the wheelchair if they are totally based on feedback information. So, what was happening when the pusher managed to maneuver the wheelchair smoothly? The fact is, the pusher looked in advance at the directions of the eyes of the person sitting on the wheelchair; there was a time lag of about half a second between the two persons. The pusher did this unconsciously. What is important here is that the sharing of a context (semantic situation) is taking place between the two persons when such dynamic coherence is created in the directions of their eyes. In other words, their timing is in synchronization with each other.

These results suggest that when someone navigates oneself in a totally unfamiliar environment, his/her action needs two functions. One is a function at the level of consciousness that determines which way to go. And the other is a function at the level of unconsciousness that positions oneself in the whole environment. The latter can be referred to as "somesthesia," which can be transmitted before it is sensed. My hypothesis is that coherent actions can be created only when these two functions alternately circulate in our body.

--That has something to do with the totality of plants?

Miwa: These two functions may be indispensable for the roots of plants to grow. Since growth is an action of roots, the situation of a setting changes in response to this action. Roots determine which way to grow by understanding the situation of a specific setting surrounding them. Then, they initiate action. I don't know if plants have a function at the conscious level in this particular case. Maybe they don't. I may be personifying plants by saying this, but I gather that actions of plants are also created by these two functions. I started my study from plants in the first place. So, I would rather say I'm viewing human beings from the perspective of plants. Since plants have no brains or nerve systems, they are easier than human beings in a sense when addressing issues such as somesthesia and corporeality. Maybe human beings have vegetative somesthesia as well.

Moreover, the phenomenon where the growth rate of roots adjacent to one another becomes synchronized could take place only when the totality is shared among the roots through the interaction of the electric fields concerned. If so, manipulating or controlling electric fields from outside could clarify the situation of "a setting" and the totality, both of which are difficult to measure for communication among human beings but not for communication among plants.

As for communication among human beings, I've been conducting experimental studies on the measurement of timing over the past five to six years. It's now becoming clear that a setting is shared when each person's physical action is synchronized with another unconsciously. However, the sharing of a setting is not necessarily a sufficient condition for the sharing of a context, but rather a necessary condition for it. There is a need to study the dynamics of the relationship between a function at the level of consciousness and a function at the level of unconsciousness.

--The limitations of languages have been discussed about recently. However, we may be able to make non-verbal communication come true, if not perfectly.

Miwa: I believe so. However, I don't know if the term "non-verbal" is appropriate in this case because it also refers to body language and hand signals, both of which express signs that have meanings. What is important here is how meanings are generated. And the problem is that there are subjects that can be expressed and cannot be expressed. For example, it's quite difficult to symbolize actual somesthesia, feelings or moods such as "What a spacious room this is." Since this kind of implied information is expressed unconsciously through the body, a context can be identical in the case of face-to-face communication. By contrast, IT communication such as the Internet doesn't usually take place in a face-to-face manner. There is only an exchange of signals and expressed information, and the persons on both sides of the communication need to interpret the information themselves. The Internet cannot transmit silence or a brief pause.

Expressed information is separative and implied information is non-separative, and the latter cannot be transmitted. This issue is closely related to communicability, that is, the possibility for interaction. We usually nod or make agreeable responses when talking with someone. These actions are intended to create the possibility for interaction rather than transmitting messages to conversational partners. The context of communication could be shared by creating communicability through physical actions, a situation that is almost equivalent to the sharing of a setting.

There have been movements toward addressing this subject. In fact, researchers including myself have reported on studies of interfaces for implied information such as tangible bits. Communicability is expected to improve a great deal based on these studies. However, we need to further study this particular subject in order to support the sharing of a context, and to create media in which mutual trust is created. Specifically, there is a need to study the dynamics of the relationship between expressed information and implied information, and to develop interfaces through which they can be transmitted.

--It sounds like we will find solutions to semantics in a true sense.

Miwa: I wouldn't go so far as to say that (laughter). But fields such as science, engineering, philosophy, sociology, and art need to be linked with one another.

--Are you suggesting that communication through the Internet will become non-virtual or come close to being non-virtual?

Miwa: No question about it. It's a feeling of being together "at this moment in this place." As Professor Hiroshi Shimizu previously indicated, the technology for supporting a self-function that views both oneself and others is indispensable for community support and crisis management. But the principle of its design has not yet been established, though I believe it is possible. It depends on whether or not we can design a setting in which physical information sent by each individual is collected and integrated. I'm going to try to create a virtual setting for the time being, which I believe will lead to the development of a virtual communication system. Creativity and credibility will be jointly created in this system.

In closing, let me make this point: I think plants represent something like a spatial existence for us. There is a saying "Ancestry plant trees under which posterity will rest." In this particular case, plants provide a space in which communication between ancestry and posterity takes place. This function is equivalent to that of a coordinator linking one person to another. In other words, plants function as an interface linking one generation to another. I'm talking about an interface though which I can talk with Goethe, or an interface that acts like a professional reciter. For that matter, there could be interfaces through which techniques of artisans or corporeality that has been nurtured by companies and universities are handed down to future generations. Cross-cultural communication can be included as well. While I'm being interviewed here, the existence of plants in this room could make the situation of this setting totally different. What I'm saying now is not likely to lead to any technological development, but it means a lot to us to develop ideas based on a coexistence with plants. It is an undoubted fact that I've come to know a lot of people in various fields thanks to the study on plants.

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