Dwarkesh ClipsMay 21, 20265m

The Cost our Ancestors Paid for Intelligence – David Reich

TL;DR

High selection does not mean high cultural prestige: Reich notes that societies like those reflected in the Bible or Homer prized strength, courage, beauty, and religiosity more than abstract smarts, even if selection on intelligence-related traits may have been strong.
IQ-style intelligence may miss what mattered in prehistory: He suggests modern test performance is not the same as being dropped into a new environment and figuring out food, shelter, and survival with a small band, echoing ideas associated with Joseph Henrich.
A shared genetic bundle seems to link many life outcomes: Reich points to correlations across obesity, years of schooling, walking pace, IQ-test performance, and household wealth, saying these traits appear partly influenced by overlapping genetic variation.
Iceland is his concrete example of selection against that bundle: Over the last 100 years, he says Iceland saw selection against variants associated with the schooling-wealth-IQ cluster, possibly because higher-investing, lower-fertility strategies produced fewer children.
The real story is reproductive tradeoffs, not one-way progress: Reich compares humans to mammals versus fish, where different ecologies favor either fewer offspring with more investment or many offspring with less investment.
Even disorders like schizophrenia or bipolar may reflect a broader adaptive spectrum: He speculates that anxiety, imagination, neuroticism, and visionary thinking could be useful in contexts like shamanistic or religious traditions, even if the extreme clinical forms are harmful.

The Breakdown

Selection may have pushed hardest on intelligence-like traits when cultures barely valued intelligence at all, and David Reich's answer is that complex traits are not simple goods. He argues they sit on tradeoff curves, like many kids versus heavy investment per child, or imagination that shades into bipolar disorder, which can help in one ecology and hurt in another.