Scientists challenge a 70-year-old “lizard brain” myth

A long-standing picture of brain evolution as newer, rational layers stacked on top of an ancient “lizard brain” may be deeply misleading. Researchers found that evolution instead appears to balance two competing styles of brain wiring, expanding one while shrinking the other depending on what an animal needs to survive. Scientists challenge a 70-year-old “lizard brain” myth.

Com Many important choices seem to pit reason against emotion. Popular culture often describes that tension as a contest between two parts of the brain: a newer, more advanced center for rational thought and an ancient "lizard brain" that runs on instinct. But the evolutionary history of the brain appears to be far more complicated than a simple struggle between old and new.

"There was a theory proposed in the ’50s that the brain evolved in layers starting with basic bodily functions, to emotions in the reptilian brain, leading up to sophisticated reasoning in humans," explains Nabil Imam, an assistant professor in the School of Computational Science and Engineering and a faculty member with Georgia Tech’s Institute for Neuroscience, Neurotechnology, and Society (INNS). "This is not how an evolutionary biologist would think about the problem." Research published in Science Advances suggests that brain evolution may be better understood in terms of wiring rather than newer regions being stacked on top of older ones. By examining the organization of both biological brains and artificial neural networks, Imam and his colleagues found evidence that evolution may involve allocating a limited amount of brain space among competing wiring strategies.