A swarm of birds act as an emergent whole as opposed to a collection of individual birds. The workings of swarms have been fruitfully studied by artificial life scientists, who look for abstracted insights into life via computers and other techniques. (Walerian Walawski)


If there was a simple meaning of the often-used scientific term “emergence,” then 100-plus scientists wouldn’t have spent four days presenting, debating and not infrequently disagreeing about what it was.

But as last month’s organizers of the Earth-Life Science Institute’s “Comparative Emergence” symposium in Tokyo frequently reminded the participants, those debates and disputes are perfectly fine and to be expected given the very long history and fungibility of the concept.

At the same time, ELSI leaders also clearly thought that the term can have resonance and importance in many domains of science, and that’s why they wanted practitioners to be exposed more deeply to its meanings and powers.

Emergence is a concept commonly used in origins of life research, in complexity and artificial life science; less commonly in chemistry, biology, social and planetary sciences; and — originally – in philosophy. And in the 21st century, it is making a significant comeback as a way to think about many phenomena and processes in the world.

So what is “emergence?” Most simply, it describes the ubiquitous and hugely varied mechanisms by which simple components in nature (or in the virtual or philosophical world) achieve more complexity, and in the process become greater than the sum of all those original parts.

The result is generally novel, often surprising, and sometimes most puzzling – especially since emergent phenomena involve self-organization by the more complex whole.

Think of a collection of ants or bees and how they join leaderless by the many thousands to make something – a beehive, an ant colony – that is entirely different from the individual creatures.


The Eagle nebula is an intense region of star formation, an emergent phenomenon
that clearly creates something novel out of simpler parts. (European Space Observatory.)

Think of the combination of hydrogen and oxygen gases which make liquid water. Think of the folding of proteins that makes genetic information transfer possible. Think of the processes by which bits of cosmic dust clump and clump and clump millions of times over and in time become a planetesimal or perhaps a planet. Think of how the firing of the billions of neurons in your brain results in consciousness.

All create complexity out of component parts, produce something irreducible from those original parts, and all have been resistant to a full explanation using the usual reductionist tools of the scientific world. This doesn’t mean that something magical or divine is going on – rather, that either humans have not figured out what happens or that what happens is not comprehensible given our understanding of the laws of nature and physics.

Heady stuff, which is why the study and use of the concept of emergence has become increasingly widespread as a tool, or perhaps a pathway, to address complex problems.

Luis Campos is a historian of science and was Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology. (Nerissa Escanlar)

Before going on, a little history is in order. Luis Campos, a historian of science at the University of New Mexico and the most recent Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology, described the concept of philosophical and scientific emergence – though not the word — as going back to the Greeks, at least.

The term “emergence” comes from the Latin verb emergo which means to arise, to rise up. Its meaning and importance have ebbed and flowed, with a major flowering in the United Kingdom in the 1920s.

It is seldom discussed, Campos said at the ELSI symposium, but the modern concepts of emergence flow to some extent from dialectics of Hegel, Marx and Engels, as well as the holism of South Africa’s controversial leader and thinker, Jan Smuts.

Campos said the “emergence” of today is quite different from those iterations. His point, he said, is that major scientific approaches grow from the societal bedrock of their times – and today that means a willingness to consider possible limits to the strict scientific reductionism of the modern era.

In philosophical terms, and generally in the history of science, there are several basic forms of emergence.

The first involves surprising complexity that arises unexplained and remains so at a particular scale, though science may catch up some day and provide plausible explanations. The formation of stars and galaxies and black holes would all be considered emergent phenomena, but astrophysics is gradually learning many of the processes that allow immeasurable complexity to appear throughout the cosmos – all from the simplest of components.

The other involves complex phenomena that appear to be beyond the capacity of physical or natural laws to ever explain. The quantum world, for instance, includes the phenomenon called quantum entanglement – a physical sensation which occurs when

The endlessly different symmetrical and fractal patterns of snowflakes are an emergent phenomenon given that each starts with the same basic material and ends up looking different. (Wilson Bentley)

pairs or groups of particles cannot be described independently of the state of the other, even when the particles are separated by a large distance.

So while emergence may be, as information scientist Francis Heylighen of the Vrije Universiteit in Brussel argued at the ELSI symposium, “simple, common and natural,” it also comes in innumerable forms that can seem mysterious or, as described in the quantum world, “spooky.”

David Pines, a co-founder of the Santa Fe Institute, which specializes in complexity studies, illustrated the dimensions of the emergence debate when he wrote about it several years ago for the online publishing site “Medium.”

“We live in an emergent universe,” he wrote, “in which it is difficult, if not impossible, to identify any existing interesting scientific problem or study any social or economic behavior that is not emergent.”

In the presence of claims like this, emergence has become a phenomenon where scientific consensus – or even agreement – can be difficult to achieve. Is it a trite “buzzword,” as some argue?  Or is it a profound and important pathway to understand underlying phenomena of the world that cannot be adequately described by reductionist, deterministic science?

Some of the modern pioneers in thinking about emergence come from the world of Artificial Life, or ALife. Using computer simulations, ALife researchers study essential properties of living systems such as evolution and adaptive behavior. Since the evolutionary clock cannot go backwards to see the what attributes are inevitable and what is more random, ALife analyzes these kinds of processes by simulating lifelike behaviors and patterns within computers.

As described at the ELSI symposium by University of Tokyo ALife and complex systems specialist Takashi Ikegami, decades of work in the ALife field have led to the conclusion that the pathways to life and consciousness are created by a cascade of emergent phenomena possessing the capability for “open-ended evolution.”


Takashi Ikegami and an android he helped build as part of his decades of work in the field of Artificial Life. (Bloomberg News)


And with computing power still increasing steadily, he said that the scale at which emergent properties can be identified and traced will similarly increase. As an example of how faster and larger computers can and will scale up ALife experiments and research, he told the story of the Rubik’s cube and what became known as “God’s algorithm.”

For 30 years, mathematicians and others working to solve the famous cube puzzle concluded that the minimum number of moves needed to complete the task was 22. This was not based on the experience of some Rubik’s cube fans, but rather of sustained mathmatical analysis.

But then in 2010 a teams of computer scientists and mathemeticians with access to Google’s supercomputers found that the minimum number of moves for any of the 43 quadrillion Rubik’s position was actually a very surprising 20. This result, Ikegami argues, is a reflection of the emergence of new technological capabilities in the last decade that are changing the world.

Some other classic artificial life simulations involve virtual birds or fish that are given some very simple rules to follow about how close individuals can approach each other and how they should steers in relation to other flock or schoolmates. Those simple instructions lead to the formation of virtual swarms and schools of enormous complexity that emerge from the individual-to-group transition.

An example of the unexpected behavior that can emerge: A flock splits to avoid an obstacle and then reunite once passed.

ALife is virtual, but emergence is everywhere in the natural world as well once you know what to look for. Bénard cells, for instance, are geometrically regular convection structures that spontaneously form in water or other thicker fluids when it is heated from below and/or cooled from above.


Benard cells formed spontaneously by convection in fluids.

The cells are formed as the hotter fluid rises and the cooler sinks, a process that results in spontaneous self-organization into a regular pattern of cells. The cells would be considered to be emergent phenomena.

John Hernlund is a geophysicist and vice director ELSI, and was the lead science organizer for the conference.

“Bénard convection is a composite phenomenon that arises from the combination of simpler processes: thermal expansion, Archimedes principle, thermal conduction, and viscous resistance to shearing motion in a fluid,” he said. “Nothing about those basic constituent processes alone would enable you to predict that their combination would yield the beautiful regular geometric patterns seen in Bénard cells, and this is why these are often used as an example of emergent behavior.”

Astrophysicist Elizabeth Tasker, a professor and communicator for the Japanese Space Agency JAXA, chaired an early session on emergence which focused on how the universe and planets were formed. She said her field has generally not described that 13.7 billion year process that followed the Big Bang in terms of emergent phenomenon, but that over the week she gradually saw the usefulness and did so in particularly compelling terms.

“As an astrophysicist,” she said. “I began to see the history of the universe as a manga, with examples of emergence forming the individual frames: matter strewn around the cosmos was drawn by gravity into structures that became galaxies, gas collapsed until fusion birthed a star, rocky boulders accreted and then began to melt and circulate to produce plate tectonics.

“Each manga frame represented the introduction of a new property of the universe, one that could not be exhibited by the individual pieces that had created it. A lone gas molecule could not show the spinning spiral of a galactic disc, nor begin to fuse elements within a star. Likewise, the rocky pieces that formed a planet could not start the circulation of plate tectonics by themselves. Neighboring interactions created a system that could spawn an entirely new process.”

Alex Penn, a complexity scientist at the University of Surrey.


While emergence is most often understood in terms of physical systems, and then virtual systems that try to capture their patterns and laws, the concept also has a presence in the social and economic sciences as well.

Alex Penn of the University of Surrey, in fact, introduced emergence in the social spheres and humanities as emergent on a scale similar to what Daniel Pines said about science. “Basically, almost everything of significance that arises in the social world is emergent,” she said.

Those phenomena ranged from the rise of different kinds of economic levels of development to political movements, cultures and down to the raising of children and residential segregation.

That housing segregation has been studied sufficiently that it has been determined that when a self-identifying group becomes less than one-third of the neighborhood population, they will begin to move to move out to be closer to those they identify with. Within a relatively short period of time, a mixed neighborhood will emerge into a segregated community via self-organization.


The Schelling model of what happens as neighborhoods self-segregate.


Other examples of emergence put forward from the social and cultural worlds include traffic jams, improv jazz performances and marriage. (A married person remains themselves, but also become part of a larger and more complex entity, from which novelty and surprise are sure to arise.)

Since the emergence symposium was taking place at an institute focused on how our planet formed and how life later appeared, it was only natural that emergence in that realm was a frequent topic. How a world without biology became one with biology is emergence writ large, with simplicity transforming to complexity innumerable times in innumerable ways.

While scientists speak of the Last Universal Common Ancestor (LUCA) as the source from which all life today arose, it is also widely held that other proto-life existed and disappeared because it could not compete successfully.

The ELSI model of that process is often presented as a kind of hourglass, where evolution of all kinds — in minerals, in prebiotic polypeptides, in simple organisms – creates new systems that take over and expand until they reach a bottleneck that stops the advance. Only a newly evolved version of the entity can make it through to the next step.

Participants including evolutionary biologist Simonetta Gribaldo of the Institut Pasteur argued that there is good reason to conclude that these processes were playing out wherever they could on the early Earth, doubtless resulting in many versions of prebiotic and proto-life before the Last Universal Common Ancestor (LUCA). In other words, the path to and beyond LUCA was not only messy but had many failed efforts along the way.

It fell to geochemist and geomicrobiologist Karyn Rogers of Rensselaer Polytechnic Institute to put it all into the context of emergence.

Long active in origin of life science, she said that she has become very uncomfortable with that description of what the field is trying to understand. Like many others, she does not see the “origin of life” as a singular phenomenon and so she moved to “origins of life.”

But “origins,” too, didn’t seem right because it seemed to focus too narrowly on the compounds and processes directly associated with life. She (and others) saw a larger picture.

Rogers said she doesn’t think scientists can talk about how biology appeared and prospered without also talking about the the mineral and geochemical world from which it arose

Karyn Rogers’ research focuses on the relationships between microbial communities and environmental conditions in extreme ecosystems. (Nerissa Escanlar)

Her conclusion, then, about how to describe what happened on prebiotic Earth so long ago:

“It’s the emergence of life,” she said at the end of the symposium, not the “origin”.

“One of interesting things about emergence is that it’s that smudgy place in between that we can’t quite describe. We know it’s necessary to go from an abiotic planet to a biotic planet, but can’t quite really wrap our minds on it.

“It’s not even a series of events, it’s a series of events that led to life plus all the stuff around it as well that didn’t lead to life…all the surrounding processes. I think you need all that for life to emerge.”

She said she came into the symposium convinced that the “emergence of life” was the way to see the our biological beginnings, but that hearing about the many other understandings of emergence led her to think she didn’t understand the concept and would have to revise her views. But by the end she was back to emergence, but with a difference.

Perhaps, she said, the group could consider having “emergence” and “smudginess” become synonyms for that cross-discipline arena of simple-to-significantly more-complex transitions they had been discussing all week.

The idea was embraced by many of the other scientists.


A Livestream of the symposium is available here.