Abstract

Evolution is not synonymous with progress or perfection. Although the term is often understood as improvement, biological evolution is a sequence of changes. The idea of an evolutionary ladder, from simple organisms to humans, reflects an anthropocentric bias and has no scientific basis. MacLean’s triune brain theory of brain evolution is an example of this bias, portraying the human brain as a series of layers, starting with the primitive reptilian brain and culminating in the uniquely human neocortex. Despite being disproven, the theory remains popular, even in university psychology textbooks, when in fact all vertebrates share similar brain structures, including what we call the neocortex. In conclusion, no living organism is more evolved than another; evolution is branching, and all living beings, including humans, share a common origin.