People who live in mild weather are statistically more likely to be social, agreeable, open, and conscientious, according to new research that lends a layer of scientific credibility to a widespread American trope: Californians have way more chill.
The fact that regional climate affects day-to-day mood is fairly established in scientific literature, and anecdotally: Gray days make some people gloomy, and Seasonal Affective Disorder prompts many to turn on their sunlamps as winter envelops parts of the Northern Hemisphere. But what if what we think of as our personalities—core traits, like sociability and openness to new experiences—also comes down to the climate we live in?
That was the hypothesis of a paper (pdf) published in Nature on Monday (Nov. 27). The researchers proposed that “ambient temperature clemency [i.e. mildness] is a key factor that relates to personality,” a suggestion “rooted in the fact that, as a warm-blooded species, humans have the existential need for thermal comfort.”
Indeed, it seems adequate outdoor “thermal comfort”—how comfortably warm we are when we’re outside—is correlated with being an all-around more socially adjusted person.
The researchers looked at temperature data for 59 cities in China, and found that among the 5,587 participants they surveyed, those who were born and raised in regions where the average temperature is closer to 72 °F (22 °C) scored higher than their counterparts in colder climes on tests measuring “agreeableness, conscientiousness, and emotional stability,” as well as “extraversion and openness to experience.” They then replicated the study in the US by looking at temperature and personality-test scores for 1.6 million people living in 12,499 different ZIP codes and found the same thing: The “ambient temperature during an individual’s youth was related to the key dimensions of personality.”
All else being equal, a kid growing up in sunny, climatically pleasant Southern California may become a more outgoing, relaxed adult than a kid bracing against winter extremes in, say, the American Midwest.
“More clement temperatures facilitate social contact, for which agreeableness, conscientiousness and emotional stability are important,” the researchers write. “Moreover, clement temperatures have been shown to enhance positive mood and lead individuals to behave more prosocially.”
So what happens when those climate regimes begin to shift?
“As climate change continues across the world, we may also observe concomitant changes in human personality,” the paper suggests. The researchers did not explore what might happen when comfortably warm climates become uncomfortably hot under climate change, but other research has suggested that, among a plethora of other potentially negative effects, sleep quality will worsen, which degrades overall health and certainly doesn’t make people more laid back.