Mikhailov A.S., Calenbuhr V. (2002) Hierarchical Organization. In: From Cells to Societies. Springer Series in Synergetics. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-05062-0_8
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Hierarchical organization is typical of complex living systems. Hierarchies of two kinds should be distinguished. Evolutionary hierarchies, such as genealogical trees, are memories of a branching process. The degree of kinship represents a natural measure of distance between elements in such trees, leading to the concept of an ultrametric space. Dynamical hierarchies are formed by coexisting structures of different levels that interact to determine the system’s dynamics.