Why Are Some People Left Handed?

Written by:

July 21, 2015

Why Are Some People Left Handed?

 

Southpaw. Lefty. Ballock-handed. Ask any left-handed person, they’ve heard all the nicknames. They’ve also experienced for themselves that everything from writing to using scissors to driving a car is harder just because they prefer their left hand to their right. According to some studies, life-expectancy might even be lower for left-handed people.

Historically, left-handed people have had it harder. In the past, left-handed people were labeled everything from unclean to witches. But don’t worry, southpaws! Nowadays, you’re in good company, even though only 10 percent of people are lefties. Robert De Niro, Angelina Jolie, Barack Obama, Morgan Freeman, Oprah Winfrey, and tons of other successful people are left-handed, showing the hand you write with doesn’t stop you from doing anything. But just why are some people left-handed?

The quick answer is that it’s still a bit of a mystery. However, countless studies have been performed to try to find the reason some people prefer their left hand to their right and vice versa.

One thing scientists have noticed is that left-handedness tends to run in families, therefore it’s assumed that left-handedness has a genetic component to it. In 2007, scientists discovered a gene that appeared to be related to left-handedness. However, it may be more complex then just a matter of having or not having a certain gene.

Human geneticist Silvia Paracchini says that although there seems to be a genetic component, that gene should have been found by now. Over 100,000 people around the world have had their genes sequenced, yet no left-handed gene has been found. Since left-handedness is a trait of one in every ten people all over the world, she says “There must be an evolutionary advantage

[to being right-handed].”

Paracchini has researched the issue extensively and has found that DNA that influences handedness is the same that determines our body’s asymmetry. A condition called situs inversus may hold the key. The rare occurence causes people to have their major organs mirrored from their normal positions. So, for example, the heart would be on the right side of the body, or the liver and gall bladder are on the left side.

As a result of this asymmetry, left-handed people have larger corpus callosum– a thick band of nerve fibres in the brain that divides the left and right hemispheres of the cerebrum. This part is actually 11 percent larger in lefties, and causes communication between their two brain hemispheres to be faster.

Further research suggests that left or right-handedness is more of a spectrum than a either or situation. That would explain why some people are ambidextrous and can use both their right and left hands equally.

Lefties might even have some (although few) advantages – there are perks in sports, you might have a better memory, and many more. So be proud of your left-handedness!

By |2018-01-16T16:14:04-04:00July 21st, 2015|Featured, News, Real World, STEM - Science|0 Comments

Leave A Comment