People of the 20th century primarily analyzed the world in terms of how much it would benefit them, according to modern philosopher James Flynn.
He says that people back then didn't often think in hypotheticals. He gives this as an example: if you asked your white parent "what if you woke up black one day?" then they'd respond with "you're being dumb."
Nowadays, people are able to form logical thoughts from abstractions, or think in the hypothetical, he also claims. This explains why the average IQ rose from 70 in the 1900s to 100 today. The sort of thinking that IQ demands is more abstract in nature.
This idea blew my mind. I've been thinking about the different between blue collar vs. educated immigrants. Blue collar workers (my parents) have always been more competent at manual work, but deficient in long-term strategic planning (like saving for retirement). My partner's parents are the opposite: highly educated immigrants that are brilliant about knowing what needs to be done in the long-term to achieve life success, but far less competent at manual work.
Everyone know that intelligence is largely bred by the skills that society demands of the individual. For example, someone who grows up poor likely possesses street smart. So taking Flynn's thinking of intelligence and shifting it to a division across socioeconomic, rather than chronological, strata is an interesting paradigm shift for me.