The combined evaluation of both similarities and differences in behavior and its roots across species, developmental periods, individuals, and cultures. In linguistics, it is a method to detect genetic relationships through reconstructing the common ancestor of the languages under consideration, and by devising a plausible sequence of regular changes that originated from a common ancestor.
See Analogy (biology), Canon of parsimony, Cross-cultural psychology, Ethology, Homology, Linguistics, Serial homology (or homonony)