Why are people in some regions happier and healthier than in other regions? For the first time, an international team of historians, psychologists, and economists has linked ancient Roman borders to today’s differences in personality, health and well-being across regions. ‘Our study shows how historical events from thousands of years ago can leave long-lasting psychological effects on populations today,’ says lead researcher Martin Obschonka from the University of Amsterdam.

Major improvements in health and well-being have been unevenly distributed throughout history. One stable factor that helps explain these differences is regional variation in personality traits, such as extraversion, neuroticism or agreeableness. Obschonka explains: ‘We found regional clusters of such adaptive personality traits linked to better health and well-being.’

These regional clusters cannot be fully understood without considering historical forces that have shaped them and ancient policies casting long shadows. ‘Physical walls from the past can turn into lasting psychological barriers that still divide societies today,’ says Obschonka.

With a team of international colleagues from the UK, Germany, the Netherlands, and the US, Obschonka looked back 2,000 years to Roman times, comparing German regions influenced by Roman culture and protected by the Roman Limes wall - the frontier of the Roman empire - with those German regions outside its reach.

A lasting psychological legacy
Using advanced statistical methods and psychological data from large-scale surveys (over 70,000 respondents), the study confirms that Roman occupation has left a lasting psychological legacy: people living in former Roman territories report greater life satisfaction and better health, and also enjoy higher life expectancy.
‘Even after accounting for recent historical factors and a variety of physical and economic conditions, including geology, climate, and regional economic development, we found a clear link between Roman rule and present-day personality traits, such as higher conscientiousness and extraversion, and lower neuroticism—traits known to drive happiness and healthier lifestyles,’ says Obschonka. ‘This pattern was further confirmed using a specialised statistical method that examines the border regions along the Limes frontier.’

Investments in economic institutions
The study suggests that Roman investments in economic advancements such as the Roman road system and Roman markets and mines were crucial in creating this effect. ‘The Limes Wall marked the boundary between one of history’s most advanced and influential civilisations and the comparatively undeveloped “Barbaric” Germanic tribes,’ Obschonka explains. ‘Roman occupation left a significant and lasting economic legacy, which in turn shaped a deep and enduring macro-psychological profile, predisposing these local populations to greater happiness and better health.’
That this effect was so long-lasting could be explained by the human capacity to build on cultural advances over generations. ‘Each generation refines and improves on what it inherits,’ says Obschonka.

Relevance for other regions
To see if these findings also apply elsewhere, the researchers tested them in the Netherlands, which was also divided by the Limes along the Rhine. Despite using a smaller study area, they found similar effects of Roman influence on personality traits, with some even stronger than in Germany. ‘This suggests that the results from Germany can be applied to another country with a different history along the same Roman border. However, it remains to be seen whether this can be extended to every country that had a historical Roman influence,’ says Obschonka.
Overall, this study highlights the importance of examining ancient history to understand modern divides in happiness, health and underlying differences in personality. ‘History shapes us in ways we often overlook. The psychological borders we see today might have their roots deep in the past,’ concludes Obschonka.