Symbiosis in large-and small-scale ecological systems

Beginning with the description of biological existence and evolution, the term "symbiosis" was born in the natural world and reveals a profound pattern of interaction between things in natural ecology. From the smallest fungus and cell to the largest human and nature, symbiosis is everywhere, constantly shaping the underlying logic of our understanding of the world.

This is an abridged version of the first part of the report.

For full report, please copy the links below and paste onto a browser:

English: 

https://www.berggruen.org/activity/a-future-of-symbiosis-and-coexistence-what-is-symbiosis-and-why-should-we-want-it/

Chinese: 

https://berggruen.org.cn/activity/54

1.1 

Considerations and implementation of human-nature symbiosis: the importance of biodiversity

Professor Lu Zhi of the School of Life Sciences at Peking University is a renowned scholar and initiator in the field of environmental and animal conservation in China. She is also the director of the Peking University Center for Nature and Society, and founder of the Shan Shui Conservation Center. Professor Lu has spent a considerable amount of time researching nature conservation and sustainable development, as well as implementing public welfare projects and advocating for policy changes. In her view, the concept of “symbiosis” is not an established research topic; rather, symbiosis is a reality that is constantly unfolding around us.

During her presentation, Professor Lu shared how researching the habitat of the giant panda made her realize the complexity of symbiosis as a means of balancing the relationship between humankind and nature. 

The giant panda’s habitat is the Qinling mountain range. Positioned at the boundary of North and South China, the Qinling range is a transition zone with abundant natural resources and high ecological resilience. The area has been the staging grounds for a back-and-forth tug of war between humans and nature since ancient times: during times of war or famine, it would see large influxes of refugees, who would then depart during times of prosperity. During the planned economy era of massive steel production, the range was cultivated and local plant life was destroyed, only to be restored again during times of economic depression. When China embraced a market economy which encouraged wanton deforestation and the tenets of sustainable management were disregarded, the giant panda lost space to reproduce. It wasn’t until the establishment of a national nature preserve that the giant panda was provided with space to breed and policy protection, but then it became a matter of how the people living in the nature preserve should survive, how they could coexist with the giant panda while still making ends meet.

Professor Lu believes that protecting wildlife, protecting the environment, and protecting humanity are isomorphic goals. The important part is recognizing the complexity and possibilities of symbiotic relationships. If we take a broad view and recognize the four-billion-year history of life on Earth, we will see that Homo sapiens only emerged a brief 170,000 years ago, and we represent just one tributary of the great river of natural evolution. Yet we have obtained the ability to drastically reshape the Earth, bringing the life cycle of the planet into the Anthropocene age. No matter how powerful we’ve become, however, we are still shackled to nature. We still rely to a high degree on nature for nearly one half of our economic activity. In 2019, 50% of the global GDP either directly or indirectly came from nature and its ecosystems. But each step forward for humanity has been mirrored by a step back for the natural world; natural ecosystems have degraded an average of 47% worldwide, biodiversity is plummeting, and the relationship between humanity and nature is growing increasingly tense.

Biodiversity loss is not just an external threat, but an economic hazard as well. Even though the environmental Kuznets curve provides an experiential description of the stages of economic growth and their environmental consequences, climate change and other extreme ecological disasters are already rearing their heads. We cannot wait until all countries are prosperous to settle our environmental debt.

Through her continued commitment to public welfare projects, Professor Lu has come to believe that the “not rich but green” model of sustainable economic development is humanity’s only choice for avoiding destruction. From inviting commercial beekeepers to panda sanctuaries to aid with reforestation, to operating snow leopard conservation tours in the Sanjiangyuan Nature Reserve, to exploring how traditional Tibetan culture preserved species richness, harmonious symbiosis between humanity and the natural word requires that we both dare to imagine and dare to act.

1.2

Symbiosis between microorganisms and the human body: How does our gut microbiota define us?

Zhao Liping, a microbiologist and professor in the Department of Biochemistry and Microbiology at Rutgers and the School of Life Sciences and Technology at Shanghai Jiaotong University, is known throughout the world for his research of gut microbiota. While Professor Zhao agrees with Professor Lu Zhi that the large-scale relationship between humans and nature is important, there is a small-scale ecosystem—inside our bodies—that requires symbiosis as well. 

Professor Zhao believes that we “humans” are not the closed and singular systems we often imagine ourselves as. Research into the microorganisms that live symbiotically with us is redefining what it means to be human. The microbiome of the symbiotic microorganisms that reside in our intestines is just as complex as a tropical rainforest, and the microbes themselves possess hundreds of times more DNA than humans. Figuring out how to protect and nurture this massive microbiome, and maintain a harmonious relationship between our bodies and these microorganisms, is no less important than achieving harmony with the natural environment of the exterior world.

Professor Zhao noted at the opening of his talk that symbiosis is a fundamental concept in microbiology. Every plant and animal cell is itself a testament to symbiosis, in that the earliest formation of cell structure involved one bacterium entering into the body of another, which gradually turned into organelles that provide host cells with energy. The mitochondria that exist in nearly every human cell are one such organelle. Chlorophyll, responsible for plant photosynthesis, was also formed this way. Internal symbiosis is achieved because the host cell protects the organelle in exchange for energy.

If we look beyond the cellular level, we will find that our surface is also home to all kinds of microorganisms, from our mouths to our stomachs. The large intestine is particularly fertile ground for microorganisms. Through Professor Zhao’s research of the gut microbiome and metabolic health, he discovered the first intestinal bacterium that causes obesity in humans; developed an intervention plan for obesity and diabetes that targets the gut microbiome; and established microbiome data based on the functional group to be used for discovering new health strategies. This research has led Professor Zhao to believe that we require a new, tripartite way of looking at health.

The first aspect of this triad involves how we look at the human body, and recognizing the existence of the massive number of symbiotic microbes in our bodies. The genes which control all aspects of our life are not limited to the 20,000 or so genes we inherit from our parents; our gut microbiota, which act as a second, acquired genome, also affect us deeply. The second part of the triad is a new view of nutrition. We can no longer only consider how nutrients will affect our bodies; we must also consider how they can better protect the microorganisms inside us. Thirdly, we need a new view of disease, an understanding that the physiologically active substances produced by our gut microbiota can enter our bloodstream and drastically alter the pathological development of diseases in our bodies.

All of Professor Zhao’s research points to a profound conclusion: microorganisms depend on and coexist with humans and other living creatures. We live in a sea of microorganisms, and everything we do is accompanied by these unseen, omnipresent microbes. If this symbiotic system is damaged—if, for example, we fail to take in enough fiber, a substance which humans cannot use but which our gut microbiota needs—then these microbes will not secrete short-chain fatty acids, which in turn will make us susceptible to conditions like obesity and diabetes. If the core gut microbiota that protects our bodies could be spread vertically and horizontally to our family members through natural birth and breastfeeding, the health of future generations would be more secure. There are also some crucial types of intestinal bacteria that play important roles to the overall health of the microbiome, much like large trees in a forest that act as anchors for other vegetation. The restoration of our “intestinal forest” relies on the growth and abundance of these critical bacteria. In this regard, symbiosis is just as important for the natural ecosystem as it is for our bodily ecosystems.

Professor Zhao noted that the boundaries between people may blur as we realize just how much we exchange microorganisms in our interactions with one another. When we eat together or converse, we might be exchanging gut microbiota. If we consider this microbiota as part of our bodies (like an organ), then how can we discriminate between “you” and “me?” This is a philosophical question worth pondering.

Incorporating the dimension of time, philosophers who think about biology and environment continue to find in history the shadow of symbiosis and its possibility as a mechanism of natural evolution. Since then, symbiosis is not only the way the world comes, but also the place it goes.

2.1 

The possibilities and limitations of symbiosis as an evolutionary mechanism

Starting from a theoretical perspective, Lu Qiaoying, assistant professor in the Department of Philosophy and Religious Studies at Peking University, introduced the evolutionary basis of symbiosis. Before delving into specifics, however, Dr.Lu first provided a simple elaboration of the “philosophy of biology” research approach she would be using in her talk, describing it as philosophical analysis of the conceptual problems of biology. 

Philosophy of biology hopes to explore how to understand life itself, especially since one of the essential characteristics of life on earth is that it does not exist in a state of chaos; the boundaries between individual organisms are clearly delineated. This even prompted Aristotle’s view that individuals as organisms were the most basic existents. The phenomena of symbiosis, however, provide a serious challenge to this position.

Lichens and gut microbiota are two classic examples of early symbiosis because they spend most of their time living with other organisms in a state of mutual influence, forming what appears to be a new mode of existence in which the boundaries between actual bodies are unclear. The process by which mitochondria and chloroplasts gradually became organelles that Professor Zhao Liping remarked upon, meanwhile, is notable to biologists and philosophers because symbiosis might also be an evolutionary mechanism. One of the reasons that symbiosis was not immediately discussed by the mainstream as an evolutionary mechanism, however, was due to how the concept of symbiosis, a biological evolutionary phenomenon, could be applied to the resolution of social conflict. The idea of maintaining individuality while simultaneously promoting social cooperation was picked up by social scientists and politicians, and mainstream biologists were turned off by the politicization of symbiosis.

Another reason that research of symbiosis was neglected by evolutionists was that it conflicted with a major view of modern biology called modern evolutionary synthesis (also known as new synthesis, modern synthesis, and neo-Darwinism), a combination of Darwinian natural selection and Mendelian inheritance. The basic tenets of modern synthesis—that genes were the basic units of evolution; that evolution was change in the gene frequencies of groups composed of individual organisms; and that the fittest survived through competition and elimination—was at odds with the cooperative model proposed by symbiotic evolution. The latter was rejected as a research paradigm by mainstream biologists until a turning point in the 1960s. It is now worth researching and discussing in greater depth.

Dr.Lu noted that in the world of philosophy of biology there are two outlooks regarding life that are extremely important when discussing symbiosis as an evolutionary mechanism.

The first is a neo-Darwinian outlook, which holds that natural selection and reproduction are the essential characteristics of life, and that Darwinian individuals are the basic units of natural selection. Classic Darwinian individuals are determined along three axes: the bottleneck effect, reproductive specialization, and overall integration. The relationship between symbiotic composites and Darwinian individuals is a crucial issue when considering whether symbiotic evolution should be integrated into this outlook. The second outlook is that of organicism, which states that an organism’s primary objective is its own subsistence. This makes metabolism an organism’s most remarkable trait, followed only after by the ability to reproduce. In other words, individuality is not a trait of living things, and thus to understand life we do not need to figure out if they are individuals or symbiotic composites; rather, the essence of life activity is in collectively maintaining metabolism. This view is more accommodating to research of symbiotic evolution.

Dr.Lu believes that we still have a lot to learn about symbiosis in the context of these different outlooks on life, and she looks forward to future discussions on the topic and challenges to current thought.

2.2 

The ontology of biological and environmental symbiotic evolution

Xiao Xianjing, distinguished professor at South China Normal University, discussed the possibilities of biological and environmental symbiotic evolution from an ontological perspective.

Professor Xiao believes that after Darwin’s theory of evolution revoked humans’ demi-god status, turning us into an existent at once great and small, we relied on the subject-object thought dichotomy to place ourselves above the natural world, leading to destruction of the ecosystem. If we are to achieve harmonious symbiosis and coevolution between humans and nature, we must first clarify whether or not harmonious symbiosis and coevolution is possible between natural existents (such as between living creatures, and between living creatures and the environment). To this end there are four questions we must answer:

Is there harmonious symbiosis and coevolution among living creatures, and among living creatures and the environment, in Darwin’s theory of evolution?

From the end of the 19th century to the 1950s, there was debate among biologists about the concepts of parasitism and symbiosis. Scholars from different disciplines each had their own opinions about which phenomena should be included under the umbrella of symbiosis; some believed symbiosis should be limited to long-term mutualism between living creatures, while others believed it should include long-term mutualism, commensalism, and parasitism. Coevolution is more so reflected in mutually beneficial symbiotic systems. It exists in all interactions between species, impacting the character differentiation, genetic patterns, and regional population adaptation of the parties involved in the interaction.

According to Professor Xiao, if we focus on the relations arising from the evolution of living creatures in the natural world, there does not have to be harmonious symbiosis and coevolution among the living creatures which Darwin’s theory revealed were based on competition; however, there can be harmonious symbiosis and coevolution among the living creatures that exist because of natural selection. Multidimensional, multifaceted research has revealed that symbiosis-dominated coevolution among biological populations can be seen at all scales of the ecosystem—in coevolution of eukaryotic life forms; in mutualistic symbiotic evolution between plants and microorganisms in land ecosystems; in continuous organisms that possess multiple symbiosis models; and even in ecological communities, entire ecosystems, and the whole planet according to the Gaia hypothesis (which posits the Earth itself as a superorganism, whereby life forms on the planet’s surface optimize its physical and chemical environment, thereby satisfying its needs to the greatest extent).

The advent of the Anthropocene age (in 2019, the Anthropocene Working Group composed of 34 scientists established a new geological epoch, the Anthropocene, signifying the massive changes to the planet caused by human activities) is having radical impacts on symbiotic structures at all scales around the world—a sixth mass extinction event, climate crises, ecological debt… Professor Xiao believes that we must implement measures to ensure harmonious symbiosis and coevolution between humanity and nature. We must first build consensus, including the establishment of concepts of biological symbiosis and coevolution between organisms and the environment, and the establishment of a concept of the harmonious symbiosis and coevolution between humanity and nature. The convivialist manifesto, initiated by the French Annales school and signed by hundreds of humanities and social sciences scholars around the world, is an innovative attempt in this regard. Additionally, we should improve the human system so that the human system and the natural system can develop together and coevolve at all levels while adequately recognizing the basis of the human system and the natural system. Finally, we may also need science and technology that return to and comply with nature; and to focus on the sublation of ancient scientific traditions and more modern science in different areas so as to promote the development of ecological technology.

Professor Xiao remarked that humanity must recognize its limits. In today’s age, when substance and “people” are extremely inflated, we would do well to temper our enthusiasm, and pursue long-term symbiosis and coexistence by understanding the relationship between humanity and other existents from a broader perspective of life forms, nature, and the environment.

# # #

Participants(in alphabetic order)

Chen Xia

Research Fellow, Institute of Philosophy, Chinese Academy of Social Sciences

Gong Jun

Professor, Department of Philosophy, Sun Yat-sen University

Ishii Tsuyoshi

Professor of Chinese Philosophy, University of Tokyo, Komaba

Lu Qiaoying

Assistant Professor, Department of Philosophy and Religious Studies, Peking University

Lu Zhi

Professor and Deputy Director, Centre for Nature and Society, Peking University

Ren Xiao

Professor, Director of the Center for Chinese Foreign Policy, Fudan University

Song Bing

Vice President, Berggruen Institute

Wu Genyou

Professor, School of Philosophy, Wuhan University

Xiao Xianjing

Professor, Institute for Science, Technology and Society, South China Normal University

Yang Shijian

Associate Professor, Department of Philosophy, Xiamen University

Zhan Yiwen

Lecturer, School of Philosophy, Beijing Normal University

Zhang Xianglong

Professor, Department of Philosophy and Religious Studies,Peking University

Zhao Liping

Professor and Eveleigh-Fenton Chair of Applied Microbiology, Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, State University of New Jersey

Report composed by: Li Zhilin

Project team: Song Bing, Zhan Yiwen, Tian Xinyuan

Translator: Thomas Garbarini

This is an abridged version of the first part of the report.

For full report, please copy the links below and paste onto a browser:

English: 

https://www.berggruen.org/activity/a-future-of-symbiosis-and-coexistence-what-is-symbiosis-and-why-should-we-want-it/

Chinese: 

https://berggruen.org.cn/activity/54

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