The Evolution of Love

Given the ubiquitous nature of love, numerous hypotheses have been proposed to explain its existence. One such hypothesis refers to love as a commitment device, suggesting that romantic love evolved to foster commitment between partners and enhance their reproductive success. A new scientific article published this month (on which I am a co-author) aimed to investigate this hypothesis using a large-scale sample of 86,310 participants from 90 countries.

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Participants were asked the following question: “Assume you are currently not in a committed relationship. Imagine meeting a person who has all of the qualities you desire but who you aren’t in love with. How likely would you be to marry this person, register your partnership with this person?” The response scale ranged from 0 (I would definitely not marry this person) to 100 (I would definitely marry this person). Participants were then asked to self-report their gender, socioeconomic status, and number of children.

Additionally, the Human Development Index (HDI) was used as a composite statistic for measuring and comparing levels of development between countries. HDI is a frequently used proxy of countries’ modernization level since it combines the nation’s longevity (life expectancy at birth), education (mean years of schooling completed at 25 years old and years of schooling expected for a child), and income (Gross National Income per capita).

If romantic love is universally perceived as a force that fosters commitment between long-term partners, we expected that individuals likely to suffer greater losses from the termination of their relationships—that is, people of lower socioeconomic status, those with many children, and women—would place a higher value on romantic love compared to people with higher status, those with fewer children, and men. These predictions were supported by the data.

It was also observed that individuals from countries with a higher (versus lower) Human Development Index placed a greater level of importance on romantic love, suggesting that modernization might influence how romantic love is evaluated. Additionally, on average, participants worldwide were unwilling to commit to a long-term romantic relationship without love, highlighting romantic love’s universal importance.

In conclusion, the findings underscore the role of romantic love as a pivotal commitment mechanism, shedding light on both its universal significance and cultural variability. The study highlights its heightened importance among individuals facing socioeconomic challenges, gender disparities, and familial responsibilities while also revealing intriguing patterns across different national cultures.

The study “Love as a Commitment Device: Evidence from a Cross-Cultural Study Across 90 Countries” led by Marta Kowal and Piotr Sorokowski was published this month in the scientific journal Human Nature.