Developmental constraints presumably had a major role in channelingevolution. In particular, developmental mechanisms may havecoordinated the evolution of neocortex with that of other brainstructures. However, the rules determining the differentialexpansion of different cortical territories remain to be determinedas well as the adaptive role of cortical expansion versus that ofthe structures it is connected to. The high degree of developmentalplasticity of neocortex was probably the key to its successfulevolution.