26 July 2024
This is the second of a series of posts on complexity. We’ll be exploring some of the ways that studying complex systems gives us a more nuanced way of understanding the world, how this is relevant to all our lives, and the unique contributions we can make to this new way of understanding the world from Aotearoa New Zealand.
The Makarora River sparkles in a distinctive blue as it winds its way from the Southern Alps into Lake Wānaka. When it reaches Boiler Flat, it splits into shallow channels that flow around ever-shifting small islands in its gravel bed. This river is a braided river – an iconic feature of Te Waiponamu, the South Island of Aotearoa New Zealand.
It’s hard to imagine much life thriving among the floods, droughts, instability and tonnes of gravel that characterise braided rivers. But if we zoom out to consider their entire breadth, braided rivers support an immense diversity of life.
Braided rivers are complex systems made up of interweaving channels that change continuously as water flow shifts and deposits sediments. This creates a changing mosaic of habitats from pools, to fast-flowing channels, to islands, that are the result of interactions between flow, sediment, and organisms like plants.
The groups of species found in different parts of a braided river are constantly changing. Depending on environmental conditions and how recently it was ripped apart by a flood, a patch could be empty or comprise any combination of species. Within each of these patches, the species interact with each other in the form of competition for resources or predation.
A complex, tangled web of life holds things together across braided rivers.
What is emergence?
Surprisingly, when all these local patches of a braided river are considered together, the composition and diversity of species in the overall system tends to stabilise through time.
This stability is explained by ‘emergence’ – a key concept in complex systems. Emergence is a process we see everywhere, and occurs when small things interact to create larger things which also interact, behaving in new and unexpected ways.
The stability of whole braided rivers results from the complex interplay between physical and biological processes, feedbacks between different elements and systems, and their ability to self-organise. That is, the stability of the whole river system emerges from its unstable component parts.
Where else can we see emergence?
Complex systems cannot be described by simply adding together their parts. Instead, a higher property is made possible by the interactions or relationships operating within, and between, their parts.
Perhaps the poster child for all this is consciousness. This phenomenon has baffled scientists for centuries. Where does consciousness come from? How does it work? Although consciousness remains unexplained in many ways, scientists know that it emerges from complex interactions among a wide range of parts and processes in the brain.
We now know what the brain comprises, and how neurons – of which there are around 86 billion – work by sending electrical and chemical signals to each other. But consciousness itself remains unexplained, emerging from the interaction of neurons and the collective activity of this network in the brain. Like the whole braided river, consciousness cannot be reduced to any single neuron or neural circuit.
Emergence occurs in the social world as well. Every day, over eight billion people wake up, and go about the mundane tasks that take up most of our human lives. We get dressed, we eat, we imagine, we create, and we do what we can to survive. But our individual behaviour does not necessarily predict how societies function, because of the diverse connections and resulting complex feedbacks among humans.
We can see this in market economies where companies, civil society and governments interact. Prices and trends arise from the interaction of many buyers and sellers and government rules. These interactions can lead to outcomes and outputs not necessarily anticipated from a single exchange.
Although these interactions can have positive outcomes, such as efficient resource allocation, innovation, and overall economic welfare, they can also be undesirable. The 2007-08 Global Financial Crisis provides an example of this. In this case, emergent behaviours within financial markets, driven by complex interactions and systemic risks, led to substantial global economic and financial disruption that was largely unanticipated.
Emergence is one of the key processes that explains how our world works
Emergence is about how complex patterns, structures, and behaviours arise from interactions – giving rise to new system properties not found in the individual components alone.
In the next post in this series on the foundations of complex systems, we’ll be taking a look at how systems self-organise, adapt and evolve over time through a process known as feedback.
A collaboration between Te Pūnaha Matatini Principal Investigators Jonathan Tonkin and Julia Talbot-Jones, and illustrator Hanna Breurkes. Edited by Jonathan Burgess.