Messi, Nadal, Obama: Famous left-handers you may not know about

Today, August 13, marks International Left-Handers Day, an annual observance that recognises left-handed people and the challenges they face in a world largely designed for right-handed users.

Research suggests that left-handers make up about 10 to 12 per cent of the global population, according to lefthandersay.com.

Several famous people are left-handed, including Canadian singer Justin Bieber, who initially used a right-handed guitar and tried to play it backwards. 

Finding this difficult, his mother later bought him a left-handed guitar. Singer Dolly Parton also learned to play the guitar similarly.

Other famous left-handers include football star Lionel Messi, tennis champion Rafael Nadal, singers Lady Gaga and Sir Paul McCartney, actress Jennifer Lawrence and television host Oprah Winfrey.

Matt Groening, the creator of The Simpsons, is also left-handed. This is one reason characters such as Bart Simpson are depicted as left-handed.

Several prominent leaders have also been left-handed. Former Kenya's President, Uhuru Kenyatta, US presidents Bill Clinton and Barack Obama are all left-handed, as were former British prime ministers David Cameron and Winston Churchill.

Prince William is also left-handed, while his great-grandfather, King George VI, was naturally left-handed. However, George VI was reportedly forced by his father, King George V, to write with his right hand.

In the past, left-handed people were often treated unfairly or judged because of their hand preference, according to the BBC. 

In Britain, many were forced to use their right hands, a practice that still occurs in some countries. As a result, some people trained to use both hands became ambidextrous.

In parts of Asia, the Middle East and Africa, the left hand has traditionally been viewed as unclean. Using it to eat or give something to another person, particularly an elder, may therefore be considered rude.

According to the British broadcaster, some languages also associate the left side with weakness or negative behaviour. For example, the French word “gauche” can mean either left or clumsy, while the Latin word “sinister” means left.

During the Middle Ages, left-handed people in Britain were sometimes associated with the devil and accused of witchcraft. Some were even burned at the stake.

Evidence suggests that left-handedness has existed for hundreds of thousands of years. Researchers studying scratches on Neanderthal teeth believe some Neanderthals used their left hands to hold stone tools while cutting meat.

Scientists are still unsure what causes hand preference. Genes may play a role, but no specific set of genes has been identified. Babies may switch hands frequently, but many begin favouring one hand at around two years old.

Left-handed people may also have differences in brain organisation, although claims that they are naturally more creative have not been scientifically proven.

Left-handedness is not limited to humans. Kangaroos often favour their left paws, while many parrots use their left feet to pick up objects