Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Revenge of the Nerds 183reared apart—for the hidden complexity we should expect to find in thehuman mind."[ he hrains of mammals, like the hodies of mammals, follow a commongeneral plan. Many of the same cell types, chemicals, tissues, suborgans,way-stations, and pathways are found throughout the class, andthe major visible differences come from inflating or shrinking the parts.But under the microscope, differences appear. The number of corticalareas differs widely, from twenty or fewer in rats to fifty or more inhumans. Primates differ Irom other mammals in the number of visualareas, their interconnections, and their hookup to the motor and decisionregions of the frontal lobes. When a species has a noteworthy talent,it is reflected in the gross anatomy of its brain, sometimes in ways visibleto the naked eve. The takeover of monkeys brains by visual areas (aboutone-half the territory) reflects—more accurately, allows—their aptitudefor depth, color, motion, and visually guided grasping. Rats that relv onsonar have additional brain areas dedicated to their ultrasonic hearing,and desert mice that cache seeds arc born with a bigger hippocampus—a seat of the cognitive map—than closely related species that don'tcache.The human brain, too, tells an evolutionary story. Even a quick sideby-sidecomparison shows that the primate brain must have been considerablyre-engineered to end up as a human brain. Our brains are aboutthree times too big for a generic monkey or ape of our body size. Theinflation is accomplished by prolonging fetal brain growth for a vear afterbirth. If our bodies grew proportionally during that period, we would beten feet tall and weigh half a ton.The major lobes and patches of the brain have been revamped aswell. The olfactory bulbs, which underlie the sense of smell, have shriveledto a third of the expected primate size (already puny by mammalianstandards), and the main cortical areas for vision and movement haveshrunk proportionally as well. Within the visual system, the first slop forinformation, the primary visual cortex, takes up a smaller proportion olthe whole brain, while the later areas for complex-form processingexpand, as do the temporoparietal areas that shunt visual information tothe language and conceptual regions. The areas for hearing, especially