How climate shaped our genes

Could centuries of warming or cooling leave a mark on human DNA? That question led me to three earlier posts about personality, height and educational attainment. The results were intriguing enough to deserve a harder test.

In Did Cold Climates Select for Cold Personalities?, warming was linked to higher genetic scores for Extraversion, a trait associated with sociability and outgoing behaviour. Did Climate Change Make Humans Shorter or Taller? found higher height scores after cooling. Did Climate Cooling Select for Cognitive Abilities? suggested a cooling association too, but only when warming and cooling were analysed separately. These were clues from DNA, not measurements of ancient personalities, stature or schooling.

A larger collection of ancient European genomes now lets me revisit all three. Looking back three and five thousand years produces a surprise: height and educational-attainment scores point in different climatic directions, while the clearest personality pattern appears between places rather than through time.

Europe’s people also moved and mixed as its climate changed. Taking shared ancestry into account makes some of the associations much smaller, but does not erase every pattern. I show the results both ways, because the difference changes what we can reasonably conclude.

The full analysis below shows where the height–cooling link holds up, how the educational-attainment finding changes direction, and why the personality result depends on which question we ask. Subscribe to read the trait-by-trait findings and all seven charts, including a skin-colour and sunlight check of what these comparisons can reveal.