Intelligence of Fungi and Forest, a Network of Knowledge Beyond Human Imagination Transforms Our Vision about City.

In planning a smart city, the vision might be limited by our human intelligence. To design a city that is not merely convenient or efficient, it would be a way to incorporate intelligence beyond humans. In this discussion, we invited Dr. Yu Fukazawa, a forester who discovered the ability of fungi to have memory and make decisions and asked him about the intelligence of fungi and the vast network of knowledge woven in a forest.
Photo by Presetbase on Unsplash

Yu Fukasawa（Graduate School of Agricultural Science, Tohoku University）
Yasuto Nakanishi（Faculty of Environment and Information Studies, Keio Univ.）
Masashige Motoe（Graduate School of Engineering, Tohoku University）
Hajime Ishikawa　（Faculty of Environment and Information Studies, Keio Univ.）

Fungi are Capable of Making Decisions and Storing Memories

Nakanishi: Throughout history, humanity has been captivated by the concept of "intelligence beyond human understanding," be it in the form of gods, fairies, monsters, or even in the artificial intelligence depicted in science fiction like HAL9000 from the film "2001: A Space Odyssey," or the sentient ocean in Stanislaw Lem's novel "Solaris." It's fascinating how the collective intelligence of insects or birds can surpass human understanding and how slime mold can solve complex problems. But your research, Fukasawa, stating that "Fungi Possess Decision-Making and Memory Abilities," really caught me by surprise. The idea of fungi making decisions and remembering stuff is extraordinary! Plus, from your book, I learned that recent DNA analysis suggests fungi are more similar to animals than to plants, reminding us how much we still need to know about intelligence in our world.

These "beyond human comprehension" forms of intelligence might play a crucial role in the future design of a "Smart City." Fukasawa-san, could you share how you came up with this hypothesis of "intelligent fungi"?

Fukasawa: My research revolves around forest ecology, mainly focusing on fungi and their role in biodiversity and interactions between forest organisms. I've often thought that these forest interactions mimic how neurons interact in the brain. One morning, the idea that mycelia might be intelligent just hit me. I was reading a lot about brain science then, which influenced my thought process. I formulated a few experimental ideas to test the intelligence of fungi, and when I shared them with my mentor (I was in England then), he found it intriguing, and that's how the research began.

Nakanishi: Your research also suggests that a mycelium network could facilitate information exchange between trees, which is fascinating.

Fukasawa: Indeed, mycorrhizal fungi, which form symbiotic relationships with tree roots, can connect one tree to another. When a tree is damaged, it releases an "alarm substance," which reaches its roots, and this signal may flow through the mycelium network to other trees. This means a tree receiving the alarm starts defense mechanisms, even if it's safe. That's the kind of communication we're talking about.

Nakanishi: How come we humans are not part of such intelligent networks?

Motoe: Well, I've never received an alarm from a fungus, actually.

Nakanishi: Birds, monkeys, and other animals might be tuned into these alarms, but humans may be disconnected from these natural intelligence networks.

Fukasawa: Can you see what's behind me right now?
(Note: A remote discussion via Zoom was being held on that day.)

Motoe: It's a forest, right? The forest of Naruko?
(Note: Dr. Fukasawa researches at the Field Science Center, Graduate School of Science, Tohoku University at Naruko Onsen, Miyagi Prefecture, Japan.)

Fukasawa: I live in this Naruko forest, and I feel that simply being here has me tapping into the "intelligence of the biodiversity network." Increasing the diversity in our cities by planting more trees, like on Aoba-dori in Sendai, can enhance the city's intelligence.

Ishikawa: That's a new argument for city greening. I've never heard a suggestion like, "Cutting down too many trees might decrease the city's intelligence." It's pretty thrilling.

Motoe: I read a news piece stating, "When a Scandinavian nursery school planted diverse trees in a grassy yard and let children play in the mud, the children's immunity boosted, and they fell ill less frequently." [4]. This seems to be an example of "humans coexisting with bacteria," where humans become part of the bacterial intelligence network, with increased immunity as a metric. But if we oversimplify this to "Let's plant trees in kindergartens to boost immunity," we might overlook the more profound narrative of the "broad connection between humans and nature."

How to Understand Transcendent City-Scale Intelligence.

Nakanishi: Another fascinating aspect of fungi is their scale, which is "beyond human control" [5]. Take the honey fungus (Armillaria ostoyae) found in Oregon, USA, in 1998; its spread is around 10 square kilometers. It's challenging to comprehend this scale as a single organism...

Motoe: That's equivalent to the size of a city, right?

Nakanishi: Despite its vastness, it's one life with the same DNA, correct?

Fukasawa: Yes, it's one organism. The honey fungus, apart from its mushroom parts, develops a dense network of mycelia thick enough (about 5mm) to be visible to the naked eye. We collected these wire-like mycelia from various places and found they all shared the same DNA, confirming it was one organism. But even if parts of the fungus are torn off, both sections remain alive. Therefore, it's tough to say if they're connected over such a vast area, despite having the same DNA.

Nakanishi: This organism, as large as a city and 2,400 years old..., possessing intelligence, it's just mind-boggling. It feels like a scenario from "Solaris." How can we interact with such intelligence?

Motoe: Fukasawa-san, you've been conducting experiments with mycelium in Petri dishes, which seems like a manageable, understandable "organism." You've explained that even when massively larger or fragmented, it's still the same individual, making decisions and storing memories while communicating. Although I grasp the concept verbally, visualizing its intelligence on various scales is difficult. How do you perceive the relationship between the vastness of the fungi network and its intelligence?

Fukasawa: That's a tough one for me too... For instance, with a small sample of mycelia in a petri dish, it's easy to measure the growth rate when we manipulate temperature and comprehend it mechanistically. But when dealing with an organism of such enormity, such comparisons become impossible. As ecological researchers, we observe the behaviors of swarms comprised of diverse organisms in the field, and these gigantic fungal networks are part of that. It's hard to visualize and comprehend the behavior of such a complex system as a massive fungus. I'm still in the process of understanding it..., and there's a lot yet to be uncovered and beyond us.

The World of Fungi Revealed by DNA Analysis

Ishikawa: Fukasawa-san's insights feel very similar to how neuroscientists explain their research.

Fukasawa: Actually, when I shared my research at a neuroscience conference, it was very well received. The similarity between fungal and brain networks piqued their interest. Each species of fungi has its unique characteristics. Though we used one type for this study, we culture several in the lab. Their growth patterns differ: the kind used in the study grows towards food sources, while others grow strictly in a predetermined direction.

Ishikawa: Those sound like relatively inflexible species, haha.

Fukasawa: Exactly. I'm intrigued about why such differences exist and how each type gains an advantage.

Ishikawa: They seem to have distinct personalities. Have you given them nicknames?

Fukasawa: Yes, I do (laughs). The fungus used in my study is scientifically named Phanerochaete velutina, but I affectionately call it "Velutina-san."

Nakanishi: Calling them by nicknames implies that you perceive them as intelligent beings, right?

Motoe: Besides nicknames, our understanding of the "world of fungi" is quite limited, and so is our vocabulary. We primarily associate them with decay. This reflects our biased view of their world. Fukasawa-san, by disseminating knowledge about the "diversity of life in the soil," you're helping us reassess our environmental perceptions.

Nakanishi: Reading your book, I was startled by the revelation that "DNA analysis has entirely altered the classification of fungi." This shift has been happening since 2000.

Fukasawa: That's right. DNA analysis has been overhauling traditional classification. Scientific names are rapidly changing, which can be quite a challenge for us researchers (laughs).

Nakanishi: Your work underscored how much we have yet to learn about the world of fungi. Advancements in technology have brought us closer to understanding fungi. We used to think we could only understand them by going back to nature, but in fact, technology is facilitating a novel form of symbiosis. Your research style—utilizing DNA analysis and computers while residing in the forest—offers a new paradigm of coexistence.

Ishikawa: That's fascinating.

Nakanishi: The book, "The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins" [6], explores human nature from the perspective of human-fungus interactions. It was penned by cultural anthropologists. Traditional anthropological research involved studying human interactions within communities like Amazonian tribes or Native Americans. However, this book presents a new approach, "multi-species anthropology," illustrating human interactions through their relations with objects and other organisms, like Matsutake mushrooms, for instance. This perspective is crucial for shaping future cities.

As we enter an era of AI and Robotics, our understanding of "non-human intelligence" is being reshaped. Historically, humans have established boundaries by fighting and exterminating other creatures like bears and wolves for survival. But now, we're faced with redefining boundaries against the new "other (intelligence)" we've created. Therefore, it's fascinating to explore human nature from the perspective of "beings possessing different forms of intelligence."

Understanding the Great Forest Cycle via Fallen Tree Renewal(Nurse-log)

Nakanishi: Earlier, Fukasawa-san mentioned, "a forest is a community composed of various organisms, and the behavior of this community forms a complex system, making it hard to imagine." Different forests might evoke different unconscious feelings in humans. For instance, one forest might bring tranquility; another might make us feel sharp... Ishikawa, as a landscape architect, how do you approach forests?

Ishikawa: Well,... we shouldn't rush.

Nakanishi: We need to spend our time…

Ishikawa: More than brief contact will be required. You'll need to spend a lot of time to understand. It's like raising a child—you must not panic.

Nakanishi: Regarding the timescale, should we talk about 10 or 20 years?

Ishikawa: Exactly. In landscaping, we start from barren land, plant, and nurture until it flourishes. We can't precisely design plants or soil. So, we must let nature run its course when plants mature beyond a certain point. That's one way of handling plants.

Nakanishi: So, to truly understand fungi, we need to consider the tree's entire life cycle, from life until it decays and returns to the soil.

Fukasawa: My research is focused on wood-decay fungi. People think forests are composed of living trees, but even after a tree dies, it's still part of the forest. Fungi colonize these dead trees, breaking them down and returning them to the soil. During this "long time before returning to the soil," various life forms inhabit and live off the tree. There's a term called "nurse log," referring to the process where the next generation of trees grows on the fallen tree, which ultimately becomes the next forest. The type of tree that grows on the nurse log is influenced by the fungi that decompose it. From a human perspective, we might think of using the dead tree as firewood before it rots, but leaving the tree to decompose naturally is vital for the forest's regeneration in the long run.

Motoe: In Fukasawa-san's book, I was intrigued by the statement that "a tree falls, and within it, wood‐decay fungi thrive in a dynamic struggle." How long is this “long time" until the fallen tree returns to the soil?

Fukasawa: It varies by species. For example, conifers like cedar decompose slowly over a scale of about 100 years. Especially in colder boreal forests, dead-standing trees take hundreds of years to decompose. Wood is mostly carbon with little nutrients. As it decomposes, nutrient concentration increases, which enables fungi to colonize.

Nakanishi: In information systems, timescales are usually in seconds, minutes, or weeks at most. In control systems, they're measured in milliseconds. This is vastly different from the timescale of a forest.

Motoe: We often refer to this as real-time.

Nakanishi: When discussing smart cities, we often focus on immediate benefits like "lower electricity bills" or "fewer traffic accidents" and less on the broader picture of "what a city should be." But it should be crucial to contemplate what a smart city should be on a larger timescale.

My wife and I were raised in "New Town" in the suburbs. Within a five-minute walk, there are many ancient temples and shrines, some established with the town's creation. Similarly, I'm sure Japanese Smart Cities would incorporate shrines or temples. Ground-breaking ceremonies would likely take place, symbolic trees would be planted, and purification rituals performed.

This approach would extend the timescale for Smart Cities, but I still think the timescale envisioned within many current smart cities would not be long enough. I'd like to expand that scale.

(Note: A ground-breaking ceremony was also held on February 23rd, 2021, at Woven City, which Toyota is constructing. Toyota Holds Ground-breaking Ceremony for "Woven City" - Construction of "Woven City," a demonstration city of the future where every good and service will be connected, has begun in Higashi-Fuji (Susono City, Shizuoka Prefecture).
Cultural rituals and long-standing traditions such as ground-breaking ceremonies, tree planting, and purification rituals help bridge the gap between new-age technology and cultural heritage. The ground-breaking ceremony held at Toyota's "Woven City" is an excellent example of this fusion. The city, slated to be a demonstration city of the future, has begun construction in Higashi-Fuji, Susono City, Shizuoka Prefecture. Every good and service will be interconnected here, showcasing the concept of a truly smart city. Yet, the traditional ceremony grounding its beginning underscores the importance of maintaining a connection with cultural roots, even as we advance technologically.)

Ishikawa: It implies taking things slow and letting go of a lot of things.

Nakanishi: Letting go is indeed vital. In my previous role at the Tokyo University of Agriculture and Technology, I heard that due to the different timeframes of agriculture and engineering, there could sometimes be disagreements between faculty members of the Agricultural Department and the Engineering Department during meetings.

Ishikawa: The same sort of thing happens between people in architecture and landscape architecture. Those in architecture often lack the "wait and see" attitude. On the other hand, landscape architects tend to complete most of the work, leave a little unfinished, and then observe the progress. They believe there's no need to finalize every last detail.

Motoe: Fukasawa-san, do you feel like you're living in harmony with the rhythm of the fungi? When you tune into it, do you feel disconnected from the rest of society? Do you operate on a fungi-like timescale?

Ishikawa: Is there a sense of a human-fungi divide, in your perspective (laughs)?

Fukasawa: I'm not entirely sure... If we're speaking about fungi, the timescale can be quite fast when we're growing and experimenting with them in a regular manner. Fungi live in the moment, but their timeline extends in the context of a forest. I'm navigating both the fleeting fungi lifecycle and forests' long lifespan. When I ponder the growth of trees or the decomposition of fallen timber, I think in a grand timescale.

Complex Interactions between Organisms are the “Qualification as a Forest”

Ishikawa: Where does your definition of a "forest" start, Fukasawa-san? A park with trees isn't a forest, right? Experts in urban planning and architecture tend to label any small amount of greenery as a forest. Many landscape architects would only call it a forest if it's vast in scale.

Fukasawa: To me, a forest is "an area with a high diversity of trees, not just ones that have been planted, but also a place where interactions among various organisms such as mammals, soil organisms, and mushrooms are taking place." If there's a large fallen tree covered with moss, it feels like a forest to me.

Ishikawa: So, a place where the cycle of fallen tree renewal happens. In that case, it's hard to determine whether even places like the Meiji Shrine would be classified as a forest.

Nakanishi: "Qualification as a forest,” that's a fascinating concept. It's as if you're saying to a young park, "You're not quite a forest yet; you need another 500 years to earn that status."

Fukasawa: Ultimately, our imagination only extends to what is relevant to us. That's why it's intriguing to discover aspects that aren't directly related to me as I study the mechanisms of forests.

Motoe: Things are occurring in the forest that are unrelated to you, but do you feel they are ongoing and somehow connected to you?

Fukasawa: While it might not be relevant to me on a short timescale, I perceive that it could come back to impact me decades from now, as the Japanese proverb "Kaze ga Fukeba Okeya ga Moukaru" suggests.
(Note: its meaning is similar to butterfly effects).

Ishikawa: Whenever I venture into the forest wearing outdoor shoes and GORE-TEX, I sense that I'm not truly merging with the environment. There's a sense of alienation when I briefly enter the forest "system," protect my own "system," and then return to the city. It's as though I'm "wearing the city while visiting the forest." Fukasawa-san, how do you perceive the connection between the "forest and me"?

Fukasawa: I, too, enjoy mountain climbing and wear GORE-TEX...

Ishikawa: It feels like a sort of original sin.

Fukasawa: If we delve deeper into that, it might be similar to a person who climbs mountains while hunting for their food and striving for self-sustainability.

"Memory of the environment" created by mycelial intelligence

Nakanishi: Initially, I think cities resemble the "GORE-TEX" that Ishikawa-san mentioned. They're a sort of mechanism that strives to maintain comfort by isolating us from the natural cycles of nature. I found it fascinating when I read in one of your books, Fukasawa-san, the idea that "If humans could feel that we're 'living enveloped by a vast intelligence,' it would change our worldview." We are surrounded by intelligence in the forest, but we're detached from that intelligence when we reside in cities. If we start choosing our living places based on "what kind of intelligence do I want to be surrounded by," we may discover a new lifestyle that transcends mere convenience.

Fukasawa: When I contemplate the "massive network of Naratake mushrooms" we discussed earlier, I realize that this vast network might be transferring energy, acquired by moving it from nutrient-rich areas to those with less or by breaking down fallen trees to symbiotic plants in other parts of the forest soil, where nutrients and carbon are unevenly distributed. A massive network of mycelium may be redistributing the forest's nutrients. If we can understand such intelligence, we might be able to manage the forest well and anticipate its future shape. I have been pondering on this.

For example, Aoba-Dori Avenue in Sendai is lined with zelkova trees that symbiotically live with arbuscular mycorrhizal fungi. Planting chestnut-leaved oak and acorn trees, which form a symbiosis with ectomycorrhizal fungi, on Hirose Avenue would create a different network. The diverse tree species and their symbiotic mycorrhizal fungi networks are intriguing.

Ishikawa: To augment the intelligence of Sendai.

Motoe: We'd be assembling different forms of intelligence alongside the intelligence of the Zelkova trees.

Fukasawa: Japanese forests are fascinating. The forests are a blend of arbuscular mycorrhizal and ectomycorrhizal tree species. In the boreal forests of Russia and North America, the forests are predominantly ectomycorrhizal with many Pinaceae and Fagaceae trees. In contrast, southern forests like the Amazon are largely arbuscular mycorrhizal forests. In other words, the "network of fungi and trees" varies from place to place. However, Japanese forests contain both types. Most of Japan's reforestation species are Japanese cedar and Japanese cypress, which are arbuscular mycorrhizal species. After cedar and cypress trees are cut down, ectomycorrhizal species like konara (Quercus serrata) and chestnuts don't grow well. We can only cultivate arbuscular mycorrhizal species like maples and dogwoods because the soil is rich with arbuscular mycorrhizal fungi.

Motoe: So, the mycelium has become a "medium with the memory of cedar" and stores it in the soil. Thus, different tree species cannot penetrate that, right?

Fukasawa: Yes, they have the exact "memory of the environment.”

Motoe: The mycelium is intelligent, functioning as a memory device, like a nerve system. This results in a situation where "the entire environment is intelligent." Furthermore, its memory is skewed.

Nakanishi: If that's the case, a smart city might not need more sensors but more fungi. In this manner, considering a 1,000-year cycle could also be viewed as smart city planning. A future lifestyle might involve living with fungi in the forest, facilitated by technology.

Embracing Nature with Modern Conveniences like walking in a forest with wearing GORE-TEX

Ishikawa: I've constructed a wooden deck in my backyard, and over the last ten years, it has started to decay, with mushrooms sprouting up on it. Viewing this as a kind of 'intellectual activity' really changes my perspective... What can we do to instill this understanding and appreciation for nature, specifically forests, in our children? Is this a natural predisposition they should already have, or do we need to teach it to them?

Motoe: My daughter delights in the blossoming of a flower but is somewhat repulsed when she sees mushrooms growing. My apologies, Fukasawa-san (laugh). How can we reshape a child's perception of fungi and, in doing so, change their understanding of the environment?

Fukasawa: Well, there's much to observe. My son, for example, often urinates in the garden.

Ishikawa: Oh, right in the garden?

Fukasawa: Yes, he usually urinates from the deck towards the same spot, leading to a high ammonia concentration. This encourages the growth of numerous mushrooms. Observing this makes me aware of invisible elements in the soil.

Ishikawa: It feels like a direct connection with the body.

Motoe: Once he eats those mushrooms, it forms a cycle.

Fukasawa: True, several mushroom species are edible. There's a kind known as ammonia fungus that only grows in mole latrines. If you find that mushroom, you can trace it back to a mole's nest. Mycorrhizal fungi rely on trees as symbiotic partners, implying that these mushrooms result from a tripartite relationship between the tree, the mole, and the fungus. Moles collect leaves and build spherical nests about 30 cm underground with a toilet nearby. If the waste in the toilet doesn't decompose, it will create an unsanitary condition for the mole. This is referred to as a 'purification symbiosis.'

Ishikawa: So, a biodegradable toilet of sorts?

Fukasawa: Exactly.

Ishikawa: That's fascinating.

Nakanishi: Earlier, I mentioned the potential I see in Fukasawa-san's research approach, which leverages DNA analysis and computer technology while living in harmony with the forest. As you've pointed out, living in the forest inherently means connecting with nature. But it's also about employing advanced technology like computers and DNA analysis to enhance that connection. It seems to me a novel way of marrying technology with nature. It's not a question of regressing to past practices or purely embracing nature but rather integrating both aspects. This, I believe, is the solution to the guilt Ishikawa-san feels toward nature.

Ishikawa: So, you suggest we equip ourselves with GORE-TEX and head into the forest to connect with nature?

Nakanishi: Exactly. It's about incorporating 'intelligence that surpasses human understanding' - like that of forests and fungi - into our concept of Smart City.

Diving Deeper into Fungal Intelligence Mechanisms

Motoe: As we're nearing the end of our time, let's discuss future possibilities. Your research, Fukasawa-san, has indicated that bacteria possess intelligence, showing they can "remember directions" and "make decisions on which way to go." Given this, what kind of further developments do you foresee? Are you planning to explore different aspects of intelligence? For instance, questions like, "Is there a will?" "Is there a desire?" or "Is there an awareness of self and environment?"

Fukasawa: Well, there are two directions I'd like to go. The first is mechanistic, exploring not just my own work on mycelium and fungi but also the "memory" in organisms like yeast. This involves examining DNA expression, as we've seen instances where plants store memories of past events in their DNA. I'm curious if the same happens in mycelium.

The second direction is to explore whether the network of mycelia integrates information or if these forms of intelligence are emergent from local responses. Specifically, I plan to investigate by visualizing the flow of electrical signals or information-transmitting substances.

Capabilities like memory, decision-making, and prediction can likely be achieved without highly sophisticated mechanisms. We know even single-celled organisms like slime mold and yeast have these functions. I hypothesize that accumulating these basic forms of intelligence might result in more advanced intelligence like the brain. I see a potential continuum from simple to advanced intelligence, with a phase variation leading to a dramatic leap in intelligence as the complexity of the information network increases. About this, I plan to research how capable complex mycelial networks of fungi are at problem-solving.

Just as a single brain cell cannot grasp our "consciousness" or "intelligence," we might not be able to perceive the intelligence of an ecosystem where we are just one component. Yet, I believe some individuals with acute senses have been able to perceive something akin to the consciousness of an ecosystem and interpret it as a divine presence. This could occur at any scale where there's an ecosystem and interaction among organisms, ranging from local spirits to global religions like Buddhism. Thus, the tagline, "From fungi to Buddha," seems fitting.

Motoe: The idea of "mycelium decomposing organic matter and co-existing with trees while reflecting on soil conditions" could radically change our traditional views of ecosystems. It's a rich vision of the entire soil and environmental system, where each entity exhibits "will, desire, memory, and decision-making." If we can study and successfully articulate the underlying mechanisms of this vision, it could transform how we humans construct cities.

Ishikawa: Your research, Fukasawa-san, should be more widely read. It echoes what neuroscientists discuss, and I'm sure it would pique the interest of many people.

Nakanishi: Connecting today's discussions with various aspects of smart cities would be intriguing. We must don our GORE-TEX and smartphones as we venture into the forest to experience the fungi firsthand.

[Interview conducted via Zoom, October 27th, 2020]
(Text/Editing by Osamu Shimizu, Academic Groove, Translation by Momoko Yoshida)

[1] Slime Mold Computing, https://www.mediamatic.net/en/page/16716/slime-mold-computing. 
[2] Yu Fukasawa, Melanie Savoury & Lynne Boddy, Ecological memory and relocation decisions in fungal mycelial networks: responses to quantity and location of new resources, The ISME Journal volume 14, pages380–388 (2020).
[3] 深澤 遊, キノコとカビの生態学―枯れ木の中は戦国時代―, 共立出版 (2017/7)
[4] Marja I. Roslund et.al. Biodiversity intervention enhances immune regulation and health-associated commensal microbiota among daycare children, https://www.science.org/doi/10.1126/sciadv.aba2578
[5] Strange but True: The Largest Organism on Earth Is a Fungus - The blue whale is big, but nowhere near as huge as a sprawling fungus in eastern Oregon, Scientific American (2007/04).
[6] Anna Lowenhaupt Tsing, The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins, Princeton Univ. Press (2015/9/29).
[7] Yu Fukasawa*, Taiki Kuishi and Kenji Seiwa, Underground of forest edges : role of mycorrhizal communities on seedling establishment, Japanese Journal of Ecology, Vol. 63, No.2, p.239-249 (2013)