McGill University now admits that.

A classic science site has just made a remarkable admission: Carl Sagan (1934–1996) is wrong about something: In this case, he was wrong about us all having the storied lizard brain. He was very much attached to the idea that we have evolved layers of brains, from mud to mind. All the best people believed in it:

We have all heard that we have a lizard brain. In fact, popular wandering hero Jack Reacher is said to have a highly reliable lizard brain, a sort of primitive instinct that alerts him to what is really going on. On top of this ancestral brain, we are said to have evolved a second brain, full of emotions, shared with mammals like mice and horses. Lizards are detached, but mammals? We experience fear, anger, joy, defiance, and longing. And crowning this limbic system is what makes us uniquely human: a third brain capable of speech, of contemplation, and of complex thoughts. “You Do Not Have a Lizard Brain,” July 2, 2026

In fact, “our entire brain communicates with different regions of itself to a profoundly intricate degree”.

Good thing the experts have noticed.

At Science and Culture Today, Casey Luskin comment,s

How many of us sat through a college-level psychology or evolution course and heard the professor claim that we have a “lizard brain”? It’s just like ontogeny recapitulates phylogeny: an evolutionary model that many of us were taught in school, but it’s totally false. According to the now-defunct hypothesis about ontogeny recapitulating phylogeny, evolution tacks new stages of development onto older ones to make new types of organisms. This view would therefore claim that your ancestors originally went through a “fish” stage of development, followed by a “reptile” stage, and then finally became a mammal, etc.

“McGill University Refutes Pop-Psychology Claim that Humans Have a “Lizard Brain”,” July 7, 2026

Clearly the cultural moment is changing if even McGill University does not see any need to hang onto that stuff.