quality:correction, structural:expansion
Evolutionary claims

Paul D. MacLean, as part of his triune brain theory (which is now considered outdated), hypothesized that the limbic system is older than other parts of the forebrain, and that it developed to manage circuitry attributed to the fight or flight first identified by Hans Selye in his report of the General Adaptation Syndrome in 1936. It may be considered a part of survival adaptation in reptiles as well as mammals (including humans). MacLean postulated that the human brain has evolved three components, that evolved successively, with more recent components developing at the top/front. These components are, respectively: