running Berkeley study, researchers found that women who smiled genuinely in their college yearbook photos went on to have more stable marriages and higher wellbeing thirty years later than those whos

Key Points:

• A 2001 University of California, Berkeley study by Harker and Keltner found that women who displayed a genuine Duchenne smile in their college yearbook photos reported higher well-being and more stable marriages up to 30 years later, suggesting that such smiles reveal underlying positive dispositions rather than causing better life outcomes.
• The Duchenne smile, characterized by the crinkling of the eyes due to involuntary muscle movement, contrasts with posed smiles and is linked to warmth and ease around others, reflecting deeper personality traits visible even in a brief, highly managed photograph.
• The study’s findings are limited by its narrow sample—white, middle-class women from a private college in the late 1950s—and have not been reliably replicated in broader, more diverse populations, indicating the results should not be generalized or interpreted as causal.
• Rather than smiling itself improving life, the research suggests that individuals who naturally express positive emotions tend to receive warmer social responses, which over time can enhance relationships and well-being through cumulative social reinforcement.
• The study highlights that facial expressions can provide subtle but meaningful insights into character and social history, showing that some aspects of personality and life experience are visible early on, even in formal, posed photographs.