The reptilian brain is often blamed for our primitive instincts that can trigger fight, flight or freeze responses in us.
However, it is a myth that part of our brain originates from reptiles, says [psychologist] Christian Krog Tamnes.
The concept of a reptilian brain is part of the myth of the triune brain, a theory that was conceived by the doctor Paul D. MacLean in the 1960s.
Carl Sagan popularized this way of thinking in his book The Dragons of Eden, published in 1977.
MacLean’s idea was that our brain has evolved layer by layer.
The reptilian brain was considered to be the innermost and oldest part. This primitive brain was responsible for instincts like hunger, survival and mating.
The emotion-controlled limbic system was said to wrap around the reptilian brain, and the surrounding outermost layer was the rational neo-cortex.
Related on the SLP
Two things are wrong about this theory, says Tamnes.
First, the brain did not develop this way through evolution.
Second, instincts, emotions and reason don’t exist in separate parts of the brain, he says.
Nevertheless, the myth is alive and well. Tamnes thinks that may be because brain research sounds so convincing.
“This theory provides a seemingly simple explanation for complex things, which is appealing,” he says.
