To summarize, the study started with the smartest group of children in the entire state of California and then tracked their success throughout their entire lives. Decades later, the researchers had discovered something very interesting.

Over the last generation, we have solved tons of well-defined problems. We eradicated smallpox and polio. We landed on the moon. We built better cars, refrigerators, and televisions. We even got ~15 IQ points smarter! And how did our incredible success make us feel?

Google “smartest people in the world” and most of the results will be physicists, mathematicians, computer scientists, and chess masters. These are all difficult problems, but they are well-defined, and that makes it easy to rank people.

Much of our seeming intelligence actually comes not from raw brainpower or a plethora of instincts, but rather from the accumulated repertoire of mental tools (e.g., integers), skills (differentiating right from left), concepts (fly wheels), and categories (basic color terms) that we inherit culturally from earlier generations.