Intelligence leads to greater success than personality traits such as being nice, conscientious and generous, a study has found.
Researchers at the Universities of Bristol, Minnesota and Heidelberg devised a series of games to discover which factors lead to co-operative behaviour when people interact in social and workplace situations.
They discovered that people with a higher IQ displayed "significantly higher" levels of co-operation, which led to them earning more money as part of the game.
Those with lower intelligence failed to appropriately follow a consistent strategy and did not estimate the future consequences of their actions, they found.
Personality traits such as trust, generosity, agreeableness and conscientiousness affected behaviour but in a smaller measure than intelligence, and only initially.
The researchers concluded that a society is cohesive if people are smart enough to be consistent in their strategies and to foresee the social consequences of their actions, including the effect on others.
Professor Eugenio Proto, of the Department of Economics at the University of Bristol, said: "We wanted to explore what factors make us effective social animals.
"In other words, what enables us to behave optimally in situations when co-operation is potentially beneficial not only to us, but to our neighbours, people in the same country or who share the same planet.
"People might naturally presume that people who are nice, conscientious and generous are automatically more co-operative.
"But, through our research, we find overwhelming support for the idea that intelligence is the primary condition for a socially cohesive, co-operative society. A good heart and good behaviour have an effect too but it's transitory and small.
"An additional benefit of higher intelligence in our experiment, and likely in real life, is the ability to process information faster, hence to accumulate more extensive experience, and to learn from it.
"This scenario can be applied to the workplace, where it's likely that intelligent people who see the bigger picture and work co-operatively, will ultimately be promoted and financially rewarded."
Researchers used four games which were representative of different and specific strategic situations.
Interactions were repeated, giving time and opportunity for each participant to observe and reflect on the past behaviour of others.
The games used included Prisoner's Dilemma, Stag Hunt and Battle of the Sexes which are often used in game theory - the science of logical decision making in humans, animals and computers.
People with a higher IQ won more money per round when the strategy game involved a trade-off between current and future gains.
Conscientious people tended to be more cautious, which reduced their co-operative behaviour, the study found.
Andis Sofianos, from the Department of Economics at the University of Heidelberg, said: "The core principle of working co-operatively and seeing the bigger picture also applies to international trade, where there is overwhelming evidence that free trade is a non-zero sum game i.e. all parties could benefit.
"With education, our results suggest that focusing on intelligence in early childhood could potentially enhance not only the economic success of the individual, but the level of co-operation in society in later life."
The study is published in the Journal of Political Economy.