Abstract. It is now generally assumed that the heterogeneity of most networks in nature probably arises via preferential attachment of some sort. However, the origin of various other topological features, such as degree-degree correlations and related characteristics, is often not clear and attributed to specific functional requirements. We show how it is possible to analyse a very general scenario in which nodes gain or lose edges according to any (e.g., nonlinear) functions of local and/or global degree information. Applying our method to two rather different examples of brain development -synaptic pruning in humans and the neural network of the worm C. Elegans -we find that simple biologically motivated assumptions lead to very good agreement with experimental data. In particular, many nontrivial topological features of the worm's brain arise naturally at a critical point.PACS numbers: 64.60.aq, 89.75.Fb, 87.85.dm, Submitted to: J. Stat. Mech. (accepted, 2010) Evolving networks and the development of neural systems 2