SEVEN AND A HALF LESSONS ABOUT THE BRAIN
by Lisa Feldman Barrett
An excellent education in brain science in seven short chapters and an introduction. Barrett, a professor of psychology at Northeastern who also has appointments at Harvard Medical School and Massachusetts General Hospital, clearly knows her neuroscience. However, like in How Emotions Are Made (2017), the author deftly employs metaphor and anecdote to deliver an insightful overview of her favorite subject. Until a few decades ago, scientists divided the brain into three layers. The core consisted of the “lizard brain,” controlling basic drives such as feeding, aggression, and mating. Around 100 million years ago, mammals evolved. A mammal experiences emotions, so evolution added a layer, the limbic system, to govern them. A few hundred thousand years ago, humans acquired an outer layer—the neocortex, or grey matter—that keeps lower levels in check and allows us to be creative, rational, and highly social. In reality, Barrett writes, our brain contains no new parts, and its neurons operate no differently than those of a fish or flea. It is not even the most highly evolved—only superbly evolved for what humans do. Humans are great thinkers, but the author maintains that brains did not evolve to think but to “control your body…by predicting energy needs before they arrive so you can efficiently make worthwhile movements and survive.” Readers will agree that our senses provide essential information for prediction but may be surprised when Barrett explains that experience (i.e., memory) plays an equally vital role. A glass of water relieves your thirst immediately, but it takes 20 minutes for the water to reach your bloodstream. Your brain, predicting correctly, turns off your thirst. The narrative is so short and sweet that most readers will continue to the 35-page appendix, in which the author delves more deeply, but with no less clarity, into topics ranging from teleology to the Myers-Briggs personality test to “Plato’s writings about the human psyche."
Outstanding popular science.