Evidence of brain evolution can be seen in various fields of biology, such as paleontology, ethology, behavioral biology, cognitive psychology, molecular biology and genetics.

Paleoneurology The study of fossil brain endocasts of extinct vertebrates permits estimates of the features and time course of brain evolution.

Comparative Neurology provides evidence for the paths and outcomes of brain evolution by detailed study of neuroanatomical structure and function.

Representative nature of these brain collections Comparative study of brains can provide greater assurance about the validity of conjectures about the evolution and functional adaptation of brain structures.

Quantitative analysis of brain measurements in different mammals enables testing of hypotheses of the kinds, character and significance of evolutionary changes in brains that have taken place.