Is this triune brain theory true?
Is it true that the human being has three different brains according to the degree of evolution? The answer is easy and forceful: absolutely no. This is a completely wrong idea and, unfortunately, it is widespread in many fields of science. It has many inconsistencies in its approach, so, no, we cannot consider it as valid.
Although MacLean determined this creative solution to our intelligent brain, has no scientific backing. However, his evolutionary story about the brain did catch on in certain sectors of the scientific community because they were plausible with Charles Darwin’s ideas on the evolution of human cognition. Even the scientific popularizer Carl Sagan talks about these three brains in his popular 1977 book “The dragons of Eden” which, remember, won a Pulitzer Prize. But as early as the 1990s, scientists had already totally rejected this three-layer brain theory.
But our brain is not a layered piece of land that can be analyzed geologically, so to speak. As Lisa Feldman Barrett explains in “Seven and a half lessons on the brain” (Ed. Paidós, 2021), our brain got bigger throughout evolutionary time and, therefore, its internal structure was also reorganized. So we neither have a primitive inner lizard, nor the emotional brain of a beast, nor a new cortex that made us intelligent.
And why is this theory still popular?
While it is true that these MacLean applications were ruled out decades ago, its popularity, especially in the networks, is due to the fact that this evolutionary story is congruent, even comforting for us. It is a way of making us understand that our reasoning has overcome our most primitive and animal part and, therefore, we have conquered the planet and become the most intelligent and developed species that exists. So whate next time you are told about your reptilian brain, remember that it is just a romantic story from the past.