A new study published in The Economic Journal finds that smarter people really are more likely to help others—and the data behind that conclusion is staggering in scale. Economists Mikael Elinder and Oscar Erixson mined Swedish administrative registers covering roughly 1.2 million men and a smaller sample of about 3,000 women, linking military conscription cognitive test scores to real-world behavior.
Among the various cognitive dimensions tested, general (fluid) intelligence emerged as the single strongest predictor of prosocial behavior, outperforming other specific cognitive skills.
To test this, the team compared identical and fraternal twin brothers, using differences within twin pairs to strip out shared genetics and upbringing. Even when one twin scored higher than his brother on the cognitive test, that twin was still more likely to donate to charity, vote, and drive a green car. The team also found that income and family background explained only a minor share of the link, while education played a somewhat larger mediating role—though intelligence retained an independent effect even after accounting for it.
The findings offer some of the clearest large-scale evidence yet that cognitive ability and civic-mindedness travel together—challenging the old trope that brains and heart are somehow at odds.
The Numbers Behind the Claim
Rather than relying on surveys about good intentions, the researchers tracked three concrete, verifiable actions: donating to charity, voting in elections, and owning an environmentally friendly car. The associations were not subtle—each one standard deviation increase in intelligence was linked to a 40% higher likelihood of charitable giving, a 31% higher likelihood of voting, and a 14% higher likelihood of owning an eco-friendly vehicle.Among the various cognitive dimensions tested, general (fluid) intelligence emerged as the single strongest predictor of prosocial behavior, outperforming other specific cognitive skills.
Ruling Out the Obvious Explanations
The most compelling part of the design is how the authors tried to break the correlation. Because smarter people also tend to earn more and stay in school longer, skeptics might assume money or education—not intelligence itself—drives generosity and civic participation.To test this, the team compared identical and fraternal twin brothers, using differences within twin pairs to strip out shared genetics and upbringing. Even when one twin scored higher than his brother on the cognitive test, that twin was still more likely to donate to charity, vote, and drive a green car. The team also found that income and family background explained only a minor share of the link, while education played a somewhat larger mediating role—though intelligence retained an independent effect even after accounting for it.
Does It Hold for Women Too?
Because Swedish conscription data historically covers men, the researchers supplemented their analysis with a smaller sample of women who had taken comparable cognitive tests. The same pattern held: higher cognitive ability among women was also clearly linked to greater prosocial behavior.Why It Matters Beyond Academia
The authors argue their results connect intelligence to genuine altruistic preferences, not just savvier self-interest dressed up as generosity. One practical implication involves environmental policy: since more intelligent individuals tend to be "early adopters" of green behaviors like eco-friendly cars, the study suggests economic incentives or nudges may be more effective than moral appeals for encouraging widespread adoption of sustainable choices among the broader population.A Note on What This Doesn't Prove
| Question | What the study shows |
|---|---|
| Does higher IQ cause kindness? | Strong association even controlling for genetics/family via twins |
| Is it just about money? | Income explains only a small part of the link |
| Is it just about education? | Education matters somewhat, but intelligence has independent effect |
| Does it apply to women? | Yes, similar pattern found in smaller female sample |
| Is this specific to Sweden? | Data is Swedish only; generalizability to other countries untested |
The findings offer some of the clearest large-scale evidence yet that cognitive ability and civic-mindedness travel together—challenging the old trope that brains and heart are somehow at odds.