Why social factors mean just one in 10 people are left-handed

Scientists have long been baffled about why just one in ten people are left-handed.

But the answer may be all to do with social behaviour, researchers have claimed.

The low number of people who are left-handed has come about because of high-levels of human cooperation, Northwestern University researchers claimed.

In a highly competitive society, there would be a much closer match of right and left-handed people, Sci Guru reported.

In basketball, in stark contrast to wider society, over half of top players are left-handed.

Which hand we used is partly determined by genetics – and partly by social factors. Historically because there was a need to share tools, more people were left-handed.


Professor Daniel Abrams and his student Mark Panaggio found that if societies were perfectly competitive, everyone would use the same hand. Their findings were published in the Journal of the Royal Society of Interface yesterday.


The pair developed a model which is able to predict how many people will be right or left-handed within a given group of people. Among golfers, they were correctly able to work out that just four per cent of people use their left.


As there are a lack of left-handed golf clubs, it discourages left-handed players. For the last 5,000 years the percentage of people who are right-handed in wider society has remained at 90 per cent.


But the study explains why such a high percentage of elite sportsmen are left-handed. The researchers are the first to use empirical data to test the theory that which hand people use is about cooperation. Identical twins, despite being genetically the same, sometimes do not use the same hand.



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