Adaptability and "emergent" properties are the dominant characteristics of complex systems, whether naturally occurring or engineered. Structurally, a complex system might be made up of a large number of simpler components, or it might be formed from hierarchies of smaller numbers of interacting subsystems and work together to produce a defined function. The nucleus of a cell has all of these features, many of which may become disrupted in cancer and other disease states. The general view is that cancer progresses gradually over time; cells become premalignant, then increasingly abnormal before they become cancerous. However, recent work by Stephens et al. (2011) has revealed that cancer can emerge much more rapidly. Based on DNA sequences from multiple cancer samples of various types, they show that cancer can arise suddenly from a single catastrophic event that causes massive genomic rearrangement.