Systems Theory in Biology: The Body is Not a Machine, Volume 2

Systems theory is, in a nutshell, about the characterisation and modelling of different systems, and theorising about how they work. Systems theory has its origins in mathematics and physics, but it is broadly applied to other areas such as economics, philosophy and biology. My primary interest in systems theory lies in the application of systems theory to biology, and by extension, to the human body in movement.

The application of systems theory to the body is certainly not new, but it does seem to be gaining momentum (again) in human movement arenas. It does seem as if, slowly, we are coming around to the realisation that reductionism has limitations (well, some of us). ‘Holism’ is the new black, and there seems to be a broad consensus that we should treat the body as a whole system, because “everything’s connected”.

Everything may very well be connected, but so what? How is it connected? What are the implications of this? What does it actually look like in practice? And how the hell do you work with it? Before we can begin to look at practical application however, it is important to consider what we are really talking about. If we do not, we end up with a whole lot of talking about systems and holistic practice in theory...and a whole lot of nothing much applied in practice.

I am primarily focussed on exploring the implications of systems theory for human movement practice, not systems theory itself. So this is not a critique of systems theory but rather a starting point for looking at systems theory applied to human movement. If you have an interest in the thinking underpinning systems theory, it is very worthwhile to read further afield.

Here, I’m going to try to keep it simple..ish. Let’s start with distinguishing between ordered systems (which can be relatively more simple or more complicated) and complex systems. There are also chaotic systems, but we’ll leave those out for the sake of clarity.

A simple ordered system is one where we find the basic characteristics of linear causality, predictability and repeatability (i.e. A is causative for B, we can reliably predict for this and we will get the same result if we do the experiment repeatedly). There is one right answer. Reductionists rejoice.

In a complicated ordered system we still find fairly high degrees of predictability and repeatability...but it’s complicated. We still find causality, but it is more difficult to prove empirically. We can confidently say that A is linearly correlated with B, but the nature of any causative relationship is not obvious (correlation does not prove causality - if you did not know this before, you do now!). There is still a right answer, but there may be more than one right answer. If we have sufficient expertise and experience, we should be able to analyse the system to make credible predictions and establish causality.

Make a note that the word used above is complicated, not complex. The two words are not synonymous and in terms of systems theory the differences between the two are significant.

Then we have complex systems. In a complex system, relationships and patterns appear to exist between A and B, but neither linear causality nor linear correlation can be clearly established. It is impossible to reliably identify simple linear causative relationships within such a system (but how we try!). Two key characteristics of complex systems, which set them apart from complicated systems, are unpredictability and emergence. These two things have profound implications for how we approach such a system.

It is my observation that many practitioners pay good lip service to “the body is a whole that is greater than the sum of its parts” rhetoric. However it soon becomes apparent that when they think of the body as a whole  - a system - they are thinking of it primarily as a complicated ordered system, and not as a complex system. Or at the very least they treat the body as if it is the former type of system. This is a mistake.

Firstly, let’s look at the broader, perhaps more obvious, differences between the two types of systems:

In a complicated system there are lots of different components that all fit just so to make it work. These components interact in a predictable, mechanistic way. Complicated ordered systems can be difficult to understand but they nonetheless produce predictable and controllable outcomes. Think of a watch. Or computer hardware. Or a motorcycle engine.

In complex systems there are also lots of different components, however these components do not interact in an entirely predictable way. They are all completely interdependent in that a change to any one component will have direct, indirect, and often unforeseen, effects on every other component - as well as on the relationships between the components. Outcomes, instead of being predictable and controllable, are emergent. Think about weather systems. Then pity the fools whose job it is to predict the weather. Now let’s throw in there that biological systems are not complex machines but complex ecologies. The body is not like an ecosystem, the body is an ecosystem - and ecosystems are, by their nature, alive and therefore adaptive.

So what we have in the body is not a complicated ordered system, but a complex adaptive system. Complex adaptive systems produce emergent outcomes that cannot be reliably predicted or controlled for. Causality is opaque and never strictly linear. Professor David Snowden, a researcher in the field of knowledge management, uses the word “dispositionality”  in relation to complex adaptive systems. I like this. He writes:

“...complex adaptive systems don’t have causality, they have dispositionality. So at any one stage you can say the system is disposed to behave in this way, but you can't [reliably] predict that it will.”

This should not be an entirely alien concept. For example, if you know a little bit about epigenetics, you will know that the current thinking in this area is that, far from being causative, genes confer a “disposition” toward something. For example we can say that some one with Gene A has a higher likelihood of developing Disease B, but it would be inappropriate in the vast number of cases to say that Gene A causes Disease B. It only creates a dispositionality in the system, with the outcomes ultimately being a product of the the interaction of a range of biological and environmental factors. The nature vs nurture argument is false dichotomy if ever there was one.

Another example would be the relationship between diet and type 2 diabetes (or diet and anything, really). Whether or not a body develops type 2 diabetes depends on a complex interaction between a host of different factors, and “predicting” that someone will become a diabetic because they eat too much chocolate is just not possible. Even the relationship between smoking and lung cancer isn’t a clear case of linear causality.

And then there is the wonderful world of nociception and pain, which...actually, come to think of it ….let’s move on...

It is not difficult to guess why practitioners do not, in general, approach the body with this “complex adaptive system” mindset. Firstly, if you are a university educated doctor, physiotherapist, exercise physiologist or some such, your education will have predisposed you to think in a way which encourages viewing the body as a complicated ordered system, if you think of it as a system at all. Over the last ten years, in particular, it seems as if the allied health professions have tied themselves into knots trying to conform to a type and standard of “evidence-based practice” to which they are - to a significant degree - unsuited. But I digress!

It is much more difficult to make sense of and work with the body when instead of dealing with “A causes B and the treatment is X”, you have to contend with “A has some relationship to B but is also influenced by C and possibly D and we have no way of reliably knowing in which direction this wind is ultimately going to blow”. Uncertainty confounds! Furthermore, answering “I don’t know” to your client’s questions about what is causing their problem is rarely a good way to establish credibility as a practitioner in the eyes of Jo Public. So it’s easier just to stick with “your A caused your B”, with some muttering about the “biopsychosocial” approach and taking your client’s feelings into consideration. Whatever that looks like in practice.

As human beings we are, in general, very bad at dealing with uncertainty. I have no hesitation in saying that - as a movement practitioner - you need to develop a capacity to cope with uncertainty. You will need this to navigate your own movement practice. You will definitely need this to navigate your practice with clients or patients if you are to ever become the class of practitioner that can go beyond being a technician.

In summary, the list below is a succinct representation of the key characteristics of complicated ordered systems vs complex adaptive systems covered in this piece. These characteristics are the ones I consider to be a good starting point for delving into the practical application of systems theory to movement practice. Over the next few articles, will look at each one in more detail.

Complicated Ordered System:  Causality; Predictability; Controllable.

Complex Adaptive System: Dispositionality; Emergent; Adaptive.