Are left-handed people smarter?

Left-handed people comprise only around 10% of the global population, but a quick glance reveals that many key movers and shakers are lefties. 

For instance, three out of the last six American presidents were lefties: George H.W. Bush, Bill Clinton and Barack Obama. Plus, an eclectic slew of outliers who've rocked the world in one way or another had dominant left hands: Michelangelo, Leonardo da Vinci, Paul McCartney, David Bowie, Jimi Hendrix, James Baldwin, Nikola Tesla, Oprah Winfrey, Bill Gates and Steve Jobs, according to a 2019 report and The New York Times.  It's an impressive roster, but what does the data say? Are left-handed people smarter than righties?

To investigate this question, researchers looked at the differences in mathematical achievement between more than 2,300 right- and left-handed students between the ages of 6 and 17 in Italy. While there was no difference when looking at the easier math problems, left-handed students had a significant edge on the more difficult problems, such as associating a mathematical function to a set of data, according to the 2017 study in the journal Frontiers, led by Giovanni Sala, an assistant professor at the Institute for Comprehensive Medical Science at Fujita Health University in Japan. 

But why would a person's dominant hand have anything to do with mathematical ability? Left-handedness is associated with some surprising differences in the architecture of the brain. A 1995 meta-analysis of 43 studies in the journal Psychobiology determined that left-handers possess a significantly larger corpus callosum — the bundle of nerve fibers connecting the two hemispheres of the brain — than right-handers do. "A possibility is that the stronger connection between the two hemispheres allows the [left-handed] subject to have stronger spatial abilities, and we know that spatial abilities are connected to mathematics because mathematics is often conceptualized throughout space," said Sala, who conducted his research while at the University of Liverpool in the U.K.  Read more...

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