Complex systems theory pays much attention to simple mechanisms producing
nontrivial patterns, especially power laws. However, power laws with exponent
close to one also result from complex mixtures of mechanisms that, in
isolation, would not necessarily give this type of distribution. Probably, both
paths to the power law are relevant in nature. The second gives a plausible
explanation for some instances of power laws emerging in extremely complex
systems, such as ecosystems.Comment: To be published in Trends in Mathematics. 6 pages, 0 figure