In physics that which is called a complex system is the one that exhibits a large range of spatial scales, and modelled as exhibiting non-linear chaotic response dynamics, turbulence, and power-scaling laws. Complex systems have characteristic emergent properties that cannot be predicted and therefore are impossible to control. They are novel characteristics of the system that emerge out of interactions and relationships which are governed by non-linear, iterative processes that drive the behavior of complex systems; the arising of novel and coherent structures, patterns and properties during the process of self-organization in complex systems. In general, complex systems, man-made or natural, share many universal design patterns; concepts and principles of design that reappear in diverse, seemingly unrelated systems. These design patterns are the essential elements for building successful complex systems that can function, compete, survive, reproduce and evolve for long periods through multiple generations towards increased fitness and overall growth.
The non-trivial nature of the relationships in a complex system make the whole system non-deterministic, ambiguous or chaotic (in the mathematical sense that a very small change in initial conditions may produce a very large change in outcome), even if the individual relationships within the system are well understood.
The emergence of systems theory, cybernetics, information theory and complexity theory greatly influenced some of the basic concepts in biology. As a result, living systems are viewed as open thermodynamic systems, far from equilibrium, that constantly exchange matter, energy, and information with their surroundings. The key feature of living systems is not their composition, the nature of chemical constituents that make them up, or matter, but rather the pattern in which the matter is organized to produce various organismal forms.
A common pattern of organization is identified that typifies all living systems – the network pattern. The entire biosphere is a giant network consisting of intertwined webs or networks nesting within the larger networks. The key property of any network is non-linearity – the pattern of organization within the network goes in all directions. As information, travels along the network pattern it may take a cyclical path leading to the establishment of a feedback loop. The organization of living systems from cells to societies is replete with feedback loops, which eventually enable the living systems, including the biosphere at large, to self-regulate.
System complexity emerges from the linking and co-localization of biotic and shared abiotic niches in space and time.
This system’s thinking resulted in two important concepts in biology, autopoiesis and embodied cognition. The key feature of the autopoiesis concept is self-organization or self-making. Every organism, from single-cell microbes to complex multicellular animals, is an autopoietic unit – a system that sustains itself due to the network pattern of organization, which allows constant self-regeneration within the boundary that separates the autopoietic unit from its environment. However, autopoietic units are never truly separated from the environment. There is a structural coupling between the autopoietic unit and its environment. Structural change and organizational conservation are the keys to complex system dynamics and modeling. The structure may undergo changes as long as the autopoietic organization is preserved.
The nature of interactions between organisms and their environments is cognitive. In this biologically embodied perspective, minimal forms of cognition are present in complex agent–environment interactions rather than inner information processing. Problem solving itself often depends on the manipulation of an environment, while the sensorimotor tasks that animals routinely accomplish are actually highly complex than basic behavioral responses. Any living organism, irrespective of whether that is a bacterium or an elephant, decides autonomously, through its sensorium faced by various constraints, whether to notice a stimulus in the environment and whether to react to it. Noticing and reacting to the stimulus leads to structural changes within the organism and within its environment. Embodied cognition provides a conceptual understanding of intelligence that starts with the interaction between an agent and its environment, highlighting the intricacies of sensorimotor relations and the ways in which higher-level forms of cognition derive from and lean on perception–action relations: cognition is here a much broader phenomenon than internal, human thought and self-evidently applies to most organisms.
Biological and living systems are examples of a large and important class of dynamic open systems, which exchange energy and waste with their environment to maintain themselves, at the expense of increasing entropy in their environment. Biological and living systems exploit matter and energy as well as information and knowledge elements. Their behavior manifests itself through flows of material, energy, and information; but also through collective knowledge that is transferred from generation to generation. Living systems have both conceptual and physical aspects, but they are unique in that their emergent behaviors are associated with learning and adaptation. Human systems are especially accomplished among living systems in their ability to express meaning in the form of complex language and use that to drive emergent behaviors of other physical, conceptual, and living systems to their goals.
Symbioses by definition involve a close association and interaction between genetically dissimilar partners, meaning that their very existence as recognizable entities is fundamentally determined by their inter-relationships as portrayed. The nature and stability of those inter-relationships are dependent on multiple factors in both their abiotic and biotic contexts—the environment in which each partner is embedded—any of which might be disrupted by anthropogenic change. The relationships between symbiotic partners and the mechanisms evolved to reinforce them could provide a buffer against change.
Homeostasis—the process of dynamic readjustment towards maintaining essential system variables that are subject to change—is a vital, emergent property of symbiotic systems that must be at the forefront of our thinking about how anthropogenic change impacts symbioses. System homeostasis relates directly to our defining condition that symbiotic partners share and co-construct a common environment. How partners actively niche-construct and maintain their symbiotic association determines the extent to which they are resilient and able to buffer against the degree and timescales of environmental change.
The Anthropocene forces us to re-examine our relationships with the natural world. It is not realistic to maintain a perspective that views us as detached from the Earth’s ecosystems, acting merely as custodians or guardians. The Earth system can go through different structural changes (extreme, abrupt, catastrophic) while preserving its autopoietic organization, and hence its complexity; these tipping points can be non-fatal. Earth’s history has been punctuated by several catastrophic structural changes, such as the transition from reductive to oxidative atmosphere, the mass extinction (diminished biosphere) of 50 to 90% of diversity, planetesimal impacts, and geomorphological changes. Yet, the complex (living) character of the Earth system has persisted; the stability of the Earth system as self-organization, alternate states (multistability), thresholds, and early signals of change.
We have no choice but to face Gaia and understand that we and the effects of our society are inextricably connected with all ecosystems on Earth today. Less than 3% of our Earth’s ecosystems remain untouched by human influence and whether we intend to or not, our choices have and will have profound impacts on the future of Earth’s biomes, and through reciprocal feedbacks, our own species. The fact that we have agency (and responsibility) should empower us to take a more active role.
We exist in a dynamic, multi-scale landscape in which multiple symbioses with biological, human, and cultural components are interacting, declining, forming and evolving simultaneously. Interdisciplinary approaches for dealing with wicked problems from complexity and social sciences are likely worth considering in research efforts aimed at understanding symbioses in an anthropogenically changing world. Human society is intertwined with symbioses on many scales and these relationships have been crucial in our history as a species.
We must move towards a regenerative perspective that fully acknowledges that we ourselves are partners embedded in a symbiotic biosphere within which we must act.