Snakes and ladders: The myth of the reptilian brain

4 Sep

The claim that we have a reptilian brain lurking below our mammalian cortex is now well established in the popular imagination.


However, this triune brain hypotheses is almost certainly false. Here is an excerpt from the abstract to a paper I read at a meeting of the American Educational Research Association:

“MacLean’s triune brain model of brain evolution continues to be controversial. This paper argues that, while MacLean made a real contribution in his effort to link brain anatomy, behavior, and evolution, his model assumes a progressive ladder like process that is inconsistent with modern understandings of evolutionary change. Rather we should see brain evolution as process of niche adaptation built on a mosaic of conserved and derived neurological structures.”

A draft of the entire paper is available as a pdf here.

4 Responses to “Snakes and ladders: The myth of the reptilian brain”

  1. agnophilo September 6, 2013 at 12:50 am #

    In other words it’s a simple analogy that doesn’t do justice to a complex process. However we do have reptile brain structures : P

    • jecgenovese September 6, 2013 at 12:07 pm #

      Not quite. All vertebrates share a common basic plan for the brain. What some call “the reptile brain” is simply a set of structures shared by all vertebrates. Labeling these structures as reptilian is misleading.

      Note that reptiles also have a cerebral cortex (see

      • agnophilo September 6, 2013 at 7:10 pm #

        Scientists use analogies and metaphors to explain complex concepts without going back over the same ground over and over. For instance a chemist might say that oxygen wants to bond with carbon, but any student who isn’t a complete moron knows that he is not being literal and saying oxygen has free will and a brain, but is simply using a metaphor to avoid explaining the concept of valence over and over again every time he mentions it. So yes, what you are saying is true, but we couldn’t explain complex ideas like evolution without the occasional metaphor.


  1. Reptile intelligence | peakmemory - November 20, 2013

    […] the past, I have criticized the triune brain hypothesis, which posits that we have a reptilian brain in a state of permanent war with our mammalian brain. […]

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