Complexity refers to the nature of systems which cannot be adequately described using linear models.
For our purposes we are interested in environmental systems, at the global level (climate, ocean currents, biodiversity) and within the organism (the human body) as well as the interaction between these (epidemiology).
Reductionism cf systems
Comprehending complexity is essential if we are to increase our understanding beyond that possible by simple reductionism. Reductionism is based on a model of natural phenomena which assumes that adequate understanding of phenomena is achieved by reducing these phenomena by finer and still finer gradations until all dynamics is reduced to the interaction of fully understood particles or events.
The reductionist model serves adequately for many purposes. But in the early 20th century quantum theory demonstrated the uncertainty at the most minute levels of physical analysis. Religious and spiritual thinkers had given up in the early 19th century in seeking for the ingredient which inserted life into matter (recall the experiments where scientists weighed an animal, then killed it expecting to find a difference in mass which corresponded with the presence or absence of life). Consciousness is a similarly elusive phenomenon for the physical scientists. At the systemic level, the world's most powerful computers are able to make only approximations to weather forecasting. The metaphor of the flap of the butterfly's wings in Brazil leading to a storm in China depicts graphically just how complex systems can be.
The metaphor also illustrates in another way the need for an appreciation of complexity. All our understandings of the world are models, metaphors, abstractions. They simplify natural phenomena so that our minds can comprehend them and our language can describe them, but inevitably omit influences which sit outside the model yet apply in real life. Complexity helps us remember that our abstractions are crude models, not complete descriptions of the world.
Evfit draws on an understanding of our bodies and their environment as interacting complex systems.
For example, fat loss is not solely a matter of a one-to-one relationship between calories consumed and fat lost. But nor is the amount of calories consumed irrelevant. Gaining strength or muscle mass is not simply a matter of getting the right number of reps and sets with the right exercise. Even if there was a formula which worked at the level of physiology, there is the human factor (how fired up are you, how well are you feeling, how tired are you?) or the impact of diet, weather and the influence of other people.
Recognizing our evolutionary heritage and our place in the environment point to patterns, profiles, cycles, varieties which seek to replicate for individuals today the experiences of human evolutionary success over millions of years. This is not an exact science, but it is one which can approach greater understanding and effectiveness as we apply our improved understanding of the rich and complex balances in the dynamic environment.
For an example of how our cultural preconceptions work against an appreciation of the importance of complexity and non-linearity, follow this link to Libby Robin's account of the Banded Stilt.
The following edited extract from New Scientist magazine of 21 December 2002 summarizes one of the key mathematical rules underpinning most complex systems. 'Physicists call it a power law - a relationship between two quantities such that one is proportional to a fixed power of the other. Power laws are held in high regard because they can describe all sorts of complicated phenomena, from the behaviour of neutron stars to the way traffic jams form. Record all the earthquakes on the planet in one year, for example, plot the number of quakes of each magnitude against the magnitude itself and the kind of curve you get follows a power law: the frequency of the quakes falls off in inverse proportion to their magnitude raised to some power. The stock market and the spread of disease also behave in the same way. In fact, power laws describe any system in a 'critical state' - a state where a kind of universal order can spread through a system regardless of its details.'
See also our provocative page on a balanced diet and lifestyle.