Everything in a kid’s world was nameable: foods, creatures, constellations. We were supposed to notice passing distractions; if we didn’t, we could get eaten. But we also needed a certain amount of stick-to-itiveness so we could build tools, stalk game, raise babies, and plan big. Evolution favored early humans who could both stay on task and switch tasks when needed, and our prefrontal cortex evolved to let us master the ability.
