Reference #333: Thinking in Systems
Complex systems often have several competing feedback loops operating simultaneously. The relative strength of these feedback loops can shift over time; this leads to shifting dominance of different loops and is a cause of complex behaviour.
For example, a population has inflows of births and outflows of deaths, each affected by their own feedback loop. As levels of fertility or mortality change over time, the behaviour of the population curve also changes (exhibiting growth, decline, or stabilisation).
Meadows. Thinking in Systems, 2008. (42-46)