Emergence: how order emerges from chaos
The difference between complex and complicated
by Francisco Rodrigues, University of São Paulo.
A car comprises various parts, each developed by an engineer with a specific and carefully planned function. In the design of a car, considerations extend beyond its functionality to aspects related to safety, price, and design. When a failure occurs in a component, such as brake pads or gears in the transmission, replacement is necessary as a car lacks a self-repair system. Periodically, it is advisable to review specific items that need replacement due to wear caused by usage and time.
The human body is also made of many parts, each executing a specific function developed over millions of years of evolution. However, unlike a car, it wasn’t an engineer who designed each part. Instead, external factors shape our body, from our nervous to digestive systems. By simple rules, our bodies have been optimized for the environment in which we evolved, considering factors like light, oxygen, carbon, water, and gravity. According to Darwin’s theory of evolution, our bodies have been refined according to two fundamental principles: (i) genetic variation and (ii) survival of the fittest. Genetic variation leads to our unique differences, making some individuals better adapted to their environment. For instance, sickle cell anaemia patients exhibit a greater resistance to malaria than those with normal red blood cells. This adaptation allows them to thrive in regions where malaria is endemic, such as Africa. Over thousands of years, carriers of this type of anaemia in these regions had an evolutionary advantage and produced more offspring. Consequently, countries like Gambia, Senegal, Cameroon, Benin, and the Central African Republic have a higher incidence of sickle cell anaemia than other countries [external link]. Conversely, having anaemia is not an evolutionary advantage in temperate countries where malaria epidemics are absent. Fortunately, today, treatments are available to alleviate this condition’s symptoms.
Although cars and human bodies share several similarities, such as being composed of many interconnected parts, they have fundamental differences. While a vehicle requires an external agent to repair or replace its parts, the human body has mechanisms for repair and evolution. For instance, when an injury occurs, neutrophils are recruited to form a barrier against the invasion of microorganisms, triggering inflammation. Subsequently, fibroblasts enter the wound and start producing collagen to reconstruct damaged tissue. Finally, collagen is reorganized and modified to strengthen the scar. Thus, our body is resilient to external disturbances, evolving and adapting to the environment. Therefore, we assert that the car is a complicated system, while our body is a complex system.
“Every object that biology studies is a system of systems.” — Francois Jacob.
Many modern cars can move autonomously, thanks to a visual system developed by engineers. Despite its efficiency, this system doesn’t compare to the human eye, which evolved over millions of years in a “blind” manner. Hundreds of millions of years ago, unicellular organisms developed light-sensitive structures to survive in an environment with intense solar radiation. At that time, Earth lacked the protective atmosphere we have today, including the ozone layer. Some organisms developed photosensitive structures through mutations, allowing for extended survival as they submerged during the day to protect themselves from radiation, avoiding damage to their genetic code. With fewer harmful mutations, these organisms lived longer, producing more offspring and passing on this beneficial mutation to their descendants.
These photosensitive structures evolved and transformed into primitive organs in trilobites during the Cambrian period, approximately 500 million years ago [external link]. Over time, these organs evolved into ocular cavities, adapting to capture more light and enhancing the resolution of images formed on the retina. Simultaneously, our brain also evolved, developing the visual cortex. Thus, our visual system resembles a contemporary technological system, with cameras capturing images and video cards, processing them, improving resolution, and interpreting content through artificial neural networks. However, it’s essential to note that our visual system didn’t require a designer but rather environmental pressure that selected the most adapted organisms throughout evolution. Without environmental pressure, humans would not have appeared on our planet.
“When I say a complex system, I mean a system composed of many parts that interact in a non-simple way.” — Herbert Simon.
Our intelligence is also a result of emergence. Around 70,000 years ago, the cognitive revolution occurred, introducing new forms of communication that allowed the Homo sapiens to dominate the planet [external link]. This revolution set our species apart from other existing human species at the time, such as Neanderthals and Homo erectus. The alteration in our cognition was an emergent phenomenon that led us to comprehend the universe and develop technologies enabling us to create other intelligences, albeit artificial.
Similar to various complicated systems like cell phones, airplanes, trains, and magnetic resonance imaging devices, there are also many complex systems. Ecosystems, our society, economic systems, the internet, and the citations between scientific articles are examples of complex systems [external link]. These systems are composed of various interacting parts, but unlike a complicated system, they exhibit a fundamental property called emergence. Essentially, emergence refers to the rise of intelligent behaviour without central control or pre-designed instructions. In other words, the properties emerge from interactions among the elements of the system and with the environment.
In an anthill, for instance, tunnels facilitate proper ventilation for expelling carbon dioxide; there are regions for cultivating fungi used as food, areas for egg storage, and even cemeteries for waste disposal, forming an organized structure resembling a city. Similar to our visual system, though they may appear engineered, anthills are generated without central control [external link]. There isn’t a queen ant commanding the organization, managing activities, assigning roles, or planning daily tasks. In reality, the myth of the queen ant and the idea that she rules the nest is inaccurate. Studies show that the queen ant has a less developed nervous system than in other ant classes, such as leaf-cutters. The primary function of the queen ant is to lay eggs and maintain the emergence of new lives in the anthill.
At the same time, leaf-cutter ants perform rather basic functions, such as seeking and transporting food. Ants don’t have maps or compasses to navigate, and the food source is often at a considerable distance. So, how do they find and transport food? Through an emergent phenomenon. As they move, ants leave a trail of pheromones, ensuring the path back to the nest is not lost. When they find food, they return along the same path, reinforcing the trail and signalling to other ants that this route is promising. This procedure establishes a trail from the anthill to the food source, creating the single-file patterns we observe at our picnics.
Therefore, even though the anthill is a highly complex structure, it emerges from the interaction of quite simple elements, i.e. the ants. This behavior can be observed in the figure below, where ants build a bridge. The bridge forms when ants gather on one side of the wall. This gathering causes some ants to reach the other side, thus forming the bridge. However, they are not aware that the bridge exists, and they did not plan its construction [external link].
“You don’t need something more to get something more. That’s what emergence means.” — Murray Gell-Mann, Nobel Prize winner in Physics in 1969 and founder of the Santa Fe Institute, the first institute for the study of complex systems in the world.
This collective behaviour without central control can also be observed in bird flocks and fish schools. When we witness patterns emerging as a predator attacks a flock of birds, we are witnessing collective behaviour without central command [see a video here]. Each bird observes its neighbour and determines its action by copying its behaviour. Thus, when a hawk attacks the flock, there is a synchronous movement to increase the group’s chances of survival. This movement enables rapid information transfer throughout the system. Instead of observing the hundreds or even thousands of birds in the group, each bird focuses on just two or three neighbours to guide its movement. This behaviour leads to rapid dissemination of information, enabling the birds to evade the attack and effectively safeguard the group. In essence, without consciousness, birds exhibit behaviours that optimize information dissemination within the group, enhancing the probability of the group’s survival.
The phenomenon of emergence is also present in our brain, circulatory system, and even in the peristaltic movements in our stomach responsible for processing food [external link]. When we move our hand, neurons in the motor region fire in unison, causing muscles to contract and inducing the movement. In the heart, cells oscillate in a coordinated manner, performing synchronized beats that allow blood transport to arteries and vessels. However, this synchronous movement is not always desired. Epileptic seizures occur because cortical regions synchronize excessively, while Parkinson’s disease is a result of uninterrupted synchronization in motor regions.
This synchronization mechanism can be observed qualitatively in artificial systems. When we set metronomes to oscillate, the interaction between them generates a coordinated movement, as shown in the following figure.
“Order arises from chaos.” — Ilya Prigogine.
The interaction among oscillators leads the system to behave in an orderly manner [external link]. However, the system is quite fragile, as disturbances can disorder the system permanently. Indeed, the behaviour of complex systems lies between order and disorder, a term known as the “edge of chaos”. For example, democracies exist between authoritarian or anarchic regimes, and connections in social networks exist between regular or entirely random organizations. The German philosopher Georg Wilhelm Friedrich Hegel (1770–1831) asserted that a state of tyranny generates a demand for freedom but that when achieved, it can lead to anarchy. In balance, elements of tyranny combine with freedom, generating laws. This is how democracies find equilibrium, granting freedom to individuals while simultaneously having laws that restrict their freedom to ensure social order. Hegel believed that society constitutes an organic unity, wherein individuals are intricately connected and reliant on one another. According to him, societal progress unfolds through dialectical transformations, wherein each successive stage signifies a heightened state of awareness and liberty. That is, a society as a complex system.
Therefore, complex systems exhibit a unique combination of order and randomness, allowing complex patterns and unpredictable behaviours to emerge. In ecosystems, this characteristic is crucial, as subtle changes in the environment, such as introducing or removing a species, can trigger unpredictable cascading extinctions. An example of this occurred in Australia, where introducing only 24 European rabbits in 1859 in Melbourne led to significant population growth, harming crops and native species [external link]. Today, it is estimated that the rabbit population in Australia is on the order of 200 million.
Emergent behavior can also be observed in our society, as Adam Smith stated in his book “The Wealth of Nations.” An “invisible hand” regulates prices and finds buyers for manufactured products in the market. For example, a baker must produce quality bread at a reasonable price, ensuring the price is not higher than that of competitors. The baker, seeking their own benefit, adapts to the competition established by the market, continually improving their product to attract more customers and increase profit. Thus, by pursuing self-interest, the baker contributes to the betterment of society by offering fairly priced and higher-quality products. This dynamic applies to any item our economy produces, from manufacturing cars to the stock market.
“A system is not the sum of the behavior of its parts; it is the product of their interactions.” — Russ Ackoff.
Explanations about emergent phenomena often draw on concepts from areas like sociology, ecology, or economics. However, it is possible to observe emergent behaviours through computer simulations. In 1986, Craig Reynolds, an expert in artificial life and computational simulations, developed a program called Boids (bird-oid object) to simulate bird flocks. This program is based on three basic rules:
- Separation: behaviour in which an agent moves away from its close neighbours.
- Alignment: an agent aligns its direction with that of other local agents.
- Cohesion: an agent moves in relation to the local flock, adjusting its position relative to the group’s average.
On the Complexity Explorables website, it is possible to simulate various emergent behaviors, from birds to ants forming trails: http://www.complexity-explorables.org
Using these three basic rules, we can reproduce the emergent behaviors observed in bird flocks or fish schools. Thus, we can see that emergence occurs due to simple rules.
“Nature is pleased with simplicity. And nature is no dummy.” — Isaac Newton
We observe that nature evolves from simple rules, which generate all the complexity around us. More fundamentally, theoretical physicists have proposed that time and space are emergent properties of the interactions between the wave functions of quantum mechanics. In other words, as stated by Natalie Paquette, a physicist at the University of Washington, time and space may not be fundamental quantities but rather products of something more fundamental [external link]. In other words, space and time may be emergent, as they could arise from the structure and behavior of more basic components of nature. This idea arises from the attempt to unify Einstein’s General Theory of Relativity with Quantum Mechanics, two highly accurate but currently incompatible theories, resulting in the search for a fundamental equation that describes all interactions in the Universe. While Quantum Theory considers time and space as immutable, the Theory of Relativity treats them as relative and interrelated.
Thus, when contemplating the concept of emergence, we can assert that our existence unfolds from the intricate interaction between atoms and molecules. These elements organize themselves to give rise to organelles, intertwine in the creation of cells, establish communication for the formation of tissues and organs, and, in harmonious synergy, constitute the complexity of our body. Moreover, we are interconnected in a society influenced by economies, ecosystems, epidemics, and climate. All this complex web of relationships is embedded in a much larger system called Earth.
The emergent is different in that its components are immeasurable; it cannot be reduced to its sum or its difference. — George Henry Lewes, in Problems of Life and Mind.
In our daily lives, the study of complexity holds significant implications for our health and society. Understanding diseases and physiological processes in our bodies requires a precise description of the involved emergent processes. The spread of fake news, the emergence of polarization, and extremist regimes are emergent processes that demand a deeper understanding [external link]. Simultaneously, global warming leads us to a tipping point capable of altering various ecosystems worldwide, resulting in new adaptations, species extinction, and impacts on food production and drinking water distribution. Emergent phenomena will likely arise due to these changes, and we must be prepared to adapt to this new reality. Therefore, it is essential to grasp the concept of emergence.
Furthermore, shortly, we will witness the development of technological systems that will not only be complicated but complex. This includes self-repairing airplanes and medications that autonomously navigate our bodies to correct organs and tissues. The successful implementation of robots, autonomous cars, and intelligent machines will depend entirely on the study of complexity.
Finally, it is essential to emphasize that the study of emergence also raises philosophical questions. Are our feelings, sensations, consciousness, and intelligence the results of emergent processes in our nervous system involving cells, chemicals, hormones, and neurotransmitters? Would the following statement be correct?
“You, your joys and sorrows, your memories and ambitions, your sense of personal identity and free will, are, in fact, no more than the behavior of a vast assembly of nerve cells and their associated molecules.” — Francis Crick.
These inquiries are part of the Philosophy of Mind, which, since Cartesian dualism, seeks to understand the relationship between mind and body [external link]. These are intriguing questions, but still without answers. Therefore, the concept of emergence spans different areas of knowledge, ranging from Biology to Philosophy.
For those interested in studying the phenomenon of emergence, consider the references below. Note that we can explore this concept not only in physics, chemistry, or biology but also in philosophy, an area called emergentism. Although emergence is an observed fact in nature, its mathematical or philosophical formulation still requires advances. Therefore, it is an interesting research area for those who want to understand how the world works.
If you are curious to explore my research, visit this link:
https://sites.icmc.usp.br/francisco.
See you next time!
Additional references
Introductory books
- “Emergence: The Connected Lives of Ants, Brains, Cities, and Software,” by Steven Johnson.
- “Complexity: A Guided Tour,” by Melanie Mitchell.
- “How Nature Works: The Science of Self-Organized Criticality,” by Per Bak.
Courses
- ComplexityExplorer, Santa Fe Institute.
- Simulation and modeling of natural processes, Coursera.
- Introduction to Complexity Science, Coursera.
Advanced books
- “Introduction to the Theory of Complex Systems,” by Stefan Thurner, Rudolf Hanel, and Peter Klimek.
- “Modeling Complex Systems,” by Nino Boccara.
- “Dynamics of Complex Systems,” by Yaneer Bar-Yam.
Papers
- 'Complex Systems: A Survey", M. E. J. Newman, arXiv:1112.1440.
- Complex networks: Augmenting the framework for the study of complex systems, LAN Amaral, JM Ottino — The European physical journal B, 2004.
- “Complex systems: Features, similarity and connectivity”, C. H. Comin, T. K. DM. Peron, F. N. Silva, D. R. Amancio, F. A. Rodrigues, L. da F. Costa, Physics Reports, Volume 861, 25 May 2020, Pages 1–41.
