âSeven and a Half Lessons About the Brainâ Review: Gray Matter, a Userâs Manual
The human brain did not evolve for thinking. Its main purpose is to regulate our physical resources and ensure our survival. Photo: Getty Images Dec. 13, 2020 5:54 pm ET
Are you doing something rash and unwise? Blame your âlizard brain.â Our reptilian instincts, which date from when we were all cold-blooded creatures around 300 million years ago, supposedly guide all of our primal urges, from throwing a punch to having an affair. Scientists have long posited that time and evolution stratified the human brain, with the oldest and crudest lizard layer lurking at the bottom, followed by the mammalian limbic system, which controls emotion, and topped by the uniquely human neocortex, which guides rational thought. This theory not only suggests that humans are the most evolved creatures, given our deluxe add-ons, but also explains the tug of war between our animal impulses and logical ambitionsâan inner struggle Plato observed more than 2,000 years ago.