Explaining Complex Adaptive Systems using Social Groups

By Siobhan Bruce (Practicum Placement Student, Fall 2020 and Winter 2021)

Our social circles shape who we are — even as we influence our social circles. In this post, Siobhan Bruce explores friendship and group affiliation as a way to introduce and describe the basic principles of a complex adaptive system.

Our world is composed of complex adaptive systems (CAS). Wrapping your brain around the concept leads to a momentous “ah ha” moment — the real-life embodiment of the emoji with its head exploding. What are these systems? How do they relate to each other? What makes something complex?

In this post, I want to provide an illustration of complex systems using an example we all have intimate experience: friends and friend groups.

Before we begin, it’s critical to understand that a person, on their own as a singular being, is also a complex adaptive system. There many different systems working simultaneously within the human body (i.e., physiological systems, biochemical and neuroendocrine feedback systems). But in this article, I want to consider how the social circles and networks of an individual mirror some characteristics of these internal systems.

Royce Holladay defines CAS as “dynamical, self-organizing and continually changing group of semi-autonomous agents that interact in interdependent and unpredictable ways such that they create system-wide patterns. These patterns, over time, reinforce future behavior of the agents in the system.” What exactly does this mean and how does it relate to your own group of friends?

Let’s break this definition down into more manageable parts.


In a group of friends, we all act in a way that is in accordance with group expectations and rules. However, the autonomous aspect of this component suggests that we still have the ability to make personal decisions about our behaviour. For example, most of us know ‘girl code’ or ‘bro code’ and there’s this common understanding that these rules should not be broken. However, I think we can all agree that we’ve experienced one of our friends ‘breaking these rules.’

One of the most commonly understood social rules is to not gossip about others within the group. Unfortunately, I have experienced this in high school when members of my friend group decided to start gossiping about another friend within the group. While I did not personally engage in the gossiping, it reinforces the semi-autonomous component of CAS and at the end of the day the free will of agents.


While humans are semi-autonomous agents, at the same time, their actions are interdependent with each other. Individual actions of members within the friend group have an impact on the group as a whole.

For example, think of a time where either you or one of your friends were going through a tough time (e.g., a romantic break-up). Think about the way that the actions/mood of the friend who is hurt influenced the whole group and how other members of the group responded. Perhaps the group of friends wanted to go to a bar (pre-COVID-19) but the friend who is going through the breakup wanted to stay home and watch romantic comedies and eat ice cream. Are you more likely to stay at home and provide emotional support to your friend rather than going to a bar? This is an illustration of how the individual situation and actions of one member of the group shape the situation and actions of the whole group. Situations and actions of each member are interdependent and influence one another.


Building off of the previous point of systems being composed of semi-autonomous agents, let’s focus on the autonomous component of this element. Since group members are autonomous, they have free will to act as they please. They are also unpredictable. There are many factors, both internal and external, that influence how an individual behaves in any given moment.

Let’s paint a scene: it’s a holiday in which you and your friends decide to exchange gifts. You go shopping and you believe you find the most perfect gift that your friend will love. Initially, you are so excited to see their reaction that you can barely contain your excitement. But as it gets closer to the gift exchange you start to feel a little bit of doubt or worry that your friend may not love the present as much as you do. You realize that there are many factors that might influence how your friend will feel about the gift. You realize you are unable to predict other events or situations in their life that might make them feel or react differently than you imagine. (Fortunately, at the end of the day, most gifts are well appreciated!)

System-wide Patterns

The way people react to one another within a CAS — such as a friend group — creates the culture or climate of the group. System-wide patterns can be seen in different traditions or rituals. For example, when my group of high school friends and I were younger, we would annually participate in a Secret Santa gift exchange. But as we got older we slowly transitioned out of this tradition and focused more on spending time with each other rather than purchasing material objects. During this process, the dynamic within the friend group shifted and the relationships began to be built on new traditions. Thinking of the friend group as a CAS, you can see how patterns of activity impact the evolution and nature of the group.

Influencing the Behaviour of the Agents

As system-wide patterns become engrained, each member behaves according to these patterns. Patterns positively reinforce the group’s behaviour the more commonly understood behaviours are practiced. Simultaneously, the rules against behaviours that are not tolerated within the group are also reinforced.

For instance, if you and your friends are against lying, the group will value truthfulness and behave in a way that positively reinforces this. At the same time, if lying were to occur within the friend group, measures would be taken to address this behaviour. In my own friend groups, we value honesty regardless of the situation and I have been in situations where my friends have been honest (despite the nature of their actions) and I have commended and respected them more for taking accountability and honesty. While I may not agree with the actions that took place, the foundation of the friendship was still strong because we all acted in a way that positively reinforced honesty. Conversely, I have also been a part of situations where some friends chose to be dishonest and that led to a decrease in trust and a rift in the friendship.

Within any CAS, it is important to understand that the boundaries are fluid and often subject to change. To make it more complex, consider how individuals can be a part of many groups. Think about how you have had many different groups of friends throughout your education: elementary school friends, high school friends, and a whole new set of friends when you went to university. While you can still be friends with each group, you are likely to modify your behaviour based on some of the previously mentioned principles and your experiences in earlier groups. You are who you are in large part because of how you have adapted to previous groups, which in turn shapes how you adapt to new social environments. The boundaries become fuzzier when you outgrow some friends or join a new friend group. These groups are constantly changing as agents (humans) learn and grow, thus further contributing to the fluidity of these social networks (systems).

Due to the uncertainty principle mentioned earlier, it is impossible to fully understand an individual based on their friend groups. However, we could also say that it is probably impossible to understand an individual without apart from their social groups. This point becomes even more complex when you take into account the different childhood experiences that are formative when developing relationships. Dr. Gabor Mate, renowned addiction expert, has done extensive research on different childhood experiences that increase their risk for developing addictions, future traumas and how they respond to stress, how an individual reacts in social groups, and what groups they engage with.

Media and technology landscapes

Humans are social beings with a drive to create connections and relationships. One key way to expand social connections throughout history has been to more efficiently spread information and create shared experiences. The printing press (1436), paper mills (1453), telegrams (1830s), along with many other inventions have ‘layered’ onto of each other. Each development drastically changes the nature of information and how humans relate to each other as a result.

The internet, especially social media, is no different. Based on the open availability and access to information there is a high impact on information movement within a system. The evolution of information movement has changed the nature of relationships, shaping the complexity of social groups. (What does the word ‘friend’ even mean now? Does ‘friend’ strictly refer to someone you have physically met — i.e. a previous high school classmate — or does it mean someone that we regularly engage with online?)

Additionally, the COVID-19 pandemic has significantly complicated friendships. Interacting with friends online is one of the only ways to safely maintain relationships. However, I’m sure you can agree with me, by having to default to online interactions and the lack of spontaneous in-person meet-ups, maintaining a friendship requires significantly more energy. You can no longer pass your friend on campus and have a five-minute conversation. Instead, you have to schedule time into an already busy online schedule to talk with friends. I think this significantly changes the nature of friendships – conversely it has also allowed time for individuals to reflect on the foundations that keep friendships together.  Like any other complex adaptive system this will change over time.

Friend groups are by nature complex adaptive systems. However, like all complex adaptive systems, they do not exist within a vacuum. There are external factors (e.g. COVID-19 pandemic, social media) that have an impact on friendships, how we interact and how we form relationships. As James Shelley, my practicum supervisor, puts it: humans invent things, and the things we invent in turn create the world we live in – we are in a constant feedback loop of creating the influences that influence us.