Approaches to the Study of Brain Evolution
This chapter focuses on ways of studying the evolution of brains in mammals. The variability in structure and function across the brains of present-day vertebrates ranges from very simple nervous systems to an astonishing variety of complex forms that allow great differences in behavioral specializations and range. Studies of brain evolution largely depend on comparisons of traits observed in the brains of extant animals and on inferences made about brains from skull endocasts from the fossil record. A misclassification of some marsupials, such as the marsupial mole, as eutherian would confound the process of identifying ancestral traits, as did the recent claim that megabats are primates, a claim that has now been rebutted by molecular (genetic) evidence. Comparative studies of how brains develop can reveal mechanisms of phylogenetic change. Phylogenetic differences are generated by changes in aspects of brain development.
