fact, many discoveries in neuroscience are based on novel adaptations. For example, the discovery of neurogenesis in the human dentate gyrus was preceded by its discovery in adult songbirds (15, 11). The same applies to GABA in crustaceans and neurotrophins in chick embryos (24, 41). If phylogenetically related animals share neural mechanisms from a common ancestor, this supports the essential role for that mechanism in the regulation of a given behaviour or phenomenon (40). This would call for more