Wolfram’s class four cellular automata are examples of complex systems known as complex adaptive systems (CAS). A tornado or a candle is a complex system. They are also dissipative because they exist by being in a flow of energy that sustains them. They dissipate energy as it moves through. A complex adaptive system is also a dissipative system, because of the flows through it, but a complex can change its internal state in order to increase its ability to survive within its environment. It can maintain its boundaries and sustain its own existence, by adapting and changing in response to changes around it. In short, it is a system that can learn. A complex adaptive system will have some form of memory, whereby it can ‘remember’ what has happened in its history and use that information as a part of its strategy for acting more effectively in the present to create a better future. Whether it is a microscopic bacterium sensing changes in the concentration of chemical as it moves in a particular direction or a university professor gaining an understanding of quantum physics, the process is still using information gained previously to be more effective in the present.

Complex adaptive systems have a large number of separate autonomous agents operating in their own interests, while also co-operating together as a whole functional unit. They balance autonomy and connectivity. It s self organising and does not need any external controller like a driver controlling a car. Control is often decentralised through the whole system. The intense and complex interactions between the agents that make up the organism, enable a process called “emergence” where the organism acts as one unit in a way not possible by the individual agents. It is only when they all work together dynamically that the overall system maximises its location on the phase space. Complexity takes what is complex and allows it to operate in simple ways.

Complex adaptive systems often develop into nested layers where parts come together to form a greater whole, but those greater wholes themselves come together to form an even higher level of functioning. Human beings come together as families, which cooperate as communities that form cities. All the agents interact together intensely such that new emergent, organism-wide attributes develop. The new level of functioning can constrain lower levels to enable organism-wide cooperation. While an individual ant is not smart, millions of ants work together in a colony and can collaborate in extremely complex ways. A whole human society works together to enable the emergence of yet another level of complexity growing out of the previous level. As this process continues each new layer emerges, nested in the previous layer. The whole system works as a single unit while the individual agents and the individual levels still operate autonomously and different parts collaborate to form a whole multi-layered being. The layers in a complex adaptive system typically form in a fractal fashion, so what happens at one level is mirrored at other levels because fractal formations are so effective

The human body is an excellent example of a nested complex adaptive system. The agents that make up a complex adaptive system are generally complex adaptive systems in their own right. The cell is the basic unit of life with its own semi-permeable boundary that can allow necessary chemicals into the cell and prevent harmful ones from entering. It is sustained by this flow of energy. A cell is made up of self-sustaining elements such as the mitochondria, golgi apparatus, and cell nucleus that collaborate to sustain the cell.

The cells then form together to create body tissue that works together in a new organism-wide system capable of operating in ways a collection of cells never could.

Different pieces of body tissue then congregate to form body organs that again are capable of co-ordinating the actions of the various body tissues in new emergent ways.

The body organs constellate to form body systems and those body systems them work together in extremely complex ways to form a new whole level of complex organisation; a human being.

A complex adaptive system is resilient in the face of perturbations from the environment that would cause less adaptive systems to disintegrate. It, therefore, does not need perfect conditions in which to live. It can change its own state to compensate for changes in the environment to increase its ability to survive. Furthermore, it has a memory and can learn from previous experiences to take the best advantage of its situation.

The actions of a complex adaptive system are equipotent, meaning there are many different circumstances that could have led to its present situation. This means they are irreversible. We can not reverse engineer the system to see what it was like when it started.