ACROSS THE LIFESPAN
Fluid vs Crystallized Intelligence
Two kinds of smart, two different aging curves
Your brain houses two fundamentally different types of intelligence, and they age on completely opposite curves. Fluid intelligence (your ability to reason through novel problems, spot patterns, and think on your feet) peaks in your 20s and gradually declines. Crystallized intelligence (your accumulated knowledge, vocabulary, and expertise) keeps climbing well into your 60s or 70s.
In real life...
Train both. Challenge your fluid intelligence with novel puzzles, unfamiliar games, and problems you haven't seen before. Feed your crystallized intelligence by reading widely, learning new domains, and engaging in deep conversations. The interplay between the two is where real-world wisdom lives.