Intelligent people are more likely to trust others, according to a new Oxford study.
One explanation of the findings could be that more intelligent individuals are better at judging character and so they tend to form relationships with people who are less likely to betray them, researchers said.
Another reason could be that smarter individuals are better at weighing up situations, recognising when there is a strong incentive for the other person not to meet their side of the deal, they said.
Oxford University researchers based their finding on an analysis of the General Social Survey, a nationally representative public opinion survey carried out in the US every one to two years.
The study, published in the journal PLOS ONE, supports previous research that analysed data on trust and intelligence from European countries.
The authors said the research is significant because social trust contributes to the success of important social institutions, such as welfare systems and financial markets.
In addition, research shows that individuals who trust others report better health and greater happiness.
The Oxford researchers found, however, that the links between trust and health, and between trust and happiness, are not explained by intelligence.
For example, individuals who trust others might have only reported better health and greater happiness because they were more intelligent. But this turns out not to be the case.
The findings confirmed that trust is a valuable resource for an individual, and is not simply a proxy for intelligence.
"Intelligence is shown to be linked with trusting others, even after taking into account factors like marital status, education and income," said lead author Noah Carl, from the Department of Sociology.
"This finding supports what other researchers have argued, namely that being a good judge of character is a distinct part of human intelligence which evolved through natural selection.
"However, there are other possible interpretations of the evidence, and further research is needed to disentangle them," Carl said.