Almost every person, group and civilization has invented a set of narratives to explain and predict the behavior of the complex systems, natural and social, in which they spend their lives. This is hardly surprising. It comes almost naturally to any of us to invent explanations that describe the observed facts and give us a (perhaps illusory) sense of understanding. We have an innate ability for it. One might argue that this has something to do with survival, an interesting subject that is best left for another post.
Seen from the perspective of modern science, many of the myths and beliefs of earlier civilizations might now seem nothing more than lousy metaphors. Yet, it is interesting to see that it is at the level of metaphors that most of us make sense of the findings of modern science because for the vast majority of people the hard technical details are seldom accessible or understandable. A cursory glance at the futile “debates” of climate change possibly suffices to illustrate the point. I am also convinced that metaphors are the kind of qualitative conclusions that scientists use to summarize observations and results, and which make the starting point for reasoning on more elaborate theories. One might also argue that an asset of any good science communicator is the ability to create simple yet accurate metaphors of an otherwise complicated set of phenomena. So, yes, I like good metaphors and believe that they are useful when administered in wise doses and are not taken too far.
As far as metaphors of complex systems go, my favorite one is the adaptive cycle, an idea put forward and developed by Holling and colleagues , and summarized in the figure below (see also this page by the Resillience Alliance; and this wonderful article by Holling ).
In short, the adaptive cycle describes the time evolution of a complex system. Beginning with the exploitation (gamma) phase, generalist (or entrepreneurial) agents expand on a newly opened field, occupying niches and growing stronger, perhaps at the expense of other agents. Experimentation and rapid development are rife. As time goes, the realm in question becomes crowded, niches less readily available and competition hardens. In this conservation (K) phase, agents evolve to specialize in their respective niches, optimizing behavior and possibly increasing the connections and interdependence with other agents in the system. The conservative K phase might be very long and resilient, yet nothing last forever. Resources become depleted, or stored in forms and places where they cannot be easily accessed, novelty is extinguished as there is no place for change nor incentive for experimentation. The overconnected system sooner or later collapses, possibly catastrophically, and we thus enter the release (Omega) phase. In this phase, agents disappear or shrink, and the resources previously locked up by them become available again. The crash is bad for the agents that previously dominated the system, but the change opens the game for new or previously repressed agents. This is the reorganization (alpha) phase, where the landscape is open to a new colonization. A new cycle begins.
In general, the first two phases, exploitation and conservation, are often called the forward loop. The release and reorganization phases are often referred to as the backloop. Adaptive cycles in complex systems can even be conceived as forming a larger set in nested form, that is, hierarchies or levels operating at different scales in time, space, energy and matter. Holling and colleagues call this panarchy. As the reader can possibly imagine, interesting things happen to systems when the release phases of nested cycles in different levels occur at the same time.
Think of landscapes, ecosystems, organizations, economies, societies, and even personal stories. The world is rife with complex systems behaving in a pseudo-cyclic manner. The adaptive cycle has a striking resemblance to reality and even has a poetic lure . Although not fully part of the current mainstream, nor even completely accepted, the notion of adaptive cycles is well grounded in decades of observations of ecologists, and the science of complex systems and dynamical systems. As far as metaphors go, I find the adaptive cycle a powerful tool for thought, a rich framework to understand current challenges in sustainability and for developing our adaptation to a changing world. Let’s hope then that we can understand and navigate the current backloop, embracing the panarchies and finding more harmonious ways of living under the conditions of our Earth.
 Gunderson, Lance H., and C. S. Holling, eds. Panarchy: Understanding Transformations in Human and Natural Systems. Island Press, 2002.
 Holling, C. S. 2004. From complex regions to complex worlds. Ecology and Society 9(1): 11. [online] URL: http://www.ecologyandsociety.org/vol9/iss1/art11/
 Turning the wheels of life. Marcus Antoninus.