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This is the *real* reason you're left-handed

New research has shed light on the mystery

This is the *real* reason you're left-handed
03 January 2018

If you like doing stuff with your hands, then chances are you’re either left or right handed - you may even be ambidextrous if you’re an alien. Of course, most people are right handed, because that’s the coolest one, but a couple of creepy, untrustworthy tennis players out there are left-handed - I know, spooky, right? 

Up until now, not much was known about exactly why somebody liked to chop up worms with their right hand, or punch cacti with their left - it was just the way it was. However, recent research has uncovered the very scientific reason for the difference in preference.

And as the old saying goes: it’s all in the spine.

Last year, researchers from Ruhr-Universitat Bochum were doing a bunch of fancy, nerd-brained experiments which analysed gene expression in the spinal cord during the eighth to the 12th week of pregnancy, and they discovered that friendly old Mr. Spine was the one who held the secret.

Essentially, arm and hand movements (chop, punch) are started via the motor cortex in the brain, which then helpfully sends a signal to the spinal cord, which transforms it into a motion, and the worm and/or cactus is killed. 


However, the motor cortex is not connected to the spinal cord from the very start of your life, and the early signs of handedness are displayed before those connections are formed. To boil it down, at the 13th week, unborn children prefer to suck either their left or right thumb (even though it makes them look like absolute babies).

During the research, the scientists found marked differences in the segments of the spine that control the arms and the legs, as early as eight weeks into development. As such, the authors concluded:

“These results fundamentally change our understanding of the cause of hemispheric asymmetries.”

However, Carolien de Kovel, researcher at the Max Plank Institute for Psycholinguistics adds, completely undermining the other university’s research in an astonishing declaration of war:

“How exactly this left-right genetic difference in the spinal cord leads to right-handedness is, however, not yet clear.”

But still, at least we now know it’s not the left and right hemispheres of the brain that make the big decisions, it’s the big bony snake that sleeps in our back. Exciting stuff.

(Image: Tanja Heffner)