What makes us human? A combination of genes and developmental programs interacting with an environment that shapes the brain across the life span, declare two California neuroscientists.
Dubbing their study of these complex interactions “cultural biology,” Quartz (director of Caltech’s Social Cognitive Neuroscience Lab) and Sejnowski (director of the Salk Institute’s Computational Neurobiology Lab) condemn evolutionary psychology’s argument that we are cast adrift in modern society with our old hunter-gatherer savannah lifestyle. Neither naturists nor nurturists, the authors defend their not-unreasonable thesis by pointing to a detailed geological record showing rapid climate change. This called for maximum flexibility in adaptation, they contend, and probably helped build bigger brains, tools, and a habit of living in groups. Quartz and Sejnowski describe an infant’s survival mechanisms as an “internal guidance system” that will endure even as that individual’s “user’s guide to life” comes online as a result of the sociocultural shaping of the slow-to-mature prefrontal cortex and its anterior cingulate. These brain parts are key to planning, judging, and decision-making and are also linked to emotion and motivation. A derailment in these areas, specifically a hyperarousal of the orbitofrontal cortex, may be responsible for the mass suicide of cultists, group violence, and killings by high-school misfits, the authors conjecture. While they admit that the brain is more complex than we can fathom, they are ready to discourse on learning, love, intelligence, personality, and happiness, often pointing to anatomical pathways and neurochemicals as clues: low serotonin in depression and suicide, oxytocin in love, and so on. They are also quite prescriptive in later chapters. What should we to do to achieve “successful aging” and rescue American society from increasing depression and isolation? Leave the TV and Net, go out and work in the community.
Smart authors with a lot of hot stuff to report on, but they should cool it a bit.