Scientists challenge 70-year-old ‘Lizard brain’ theory of human intelligence

For decades, the human brain was like some evolutionary skyscraper: ancient instincts on the bottom, emotions in the middle, and sophisticated reasoning on the top. That’s a good reason why we sometimes feel stuck between impulse and logic. But the evolutionary story of the brain may be far messier. New research from Georgia Tech challenges the popular notion of a primitive “lizard brain” sitting below a newer, rational brain. Instead, scientists suggest, it may have been a competition between fundamentally different ways of wiring neural circuits, with limited brain space forcing different systems to compete, which influenced brain evolution. Published in Science Advances, the study draws on comparisons of biological brains and experiments on artificial neural networks to suggest a new framework for understanding the evolution of intelligence.