For the left-handed people of the world, life isn’t easy. Throughout much of history, massive stigmas attached to left-handedness meant they were singled out as everything from unclean to witches. In Medieval times, writing with your left-hand was a surefire way to be accused of being possessed by the devil; after all, the devil himself was thought to be a lefty. The world has gotten progressively more accepting of left-handed folk, but there are still some undeniable bummers associated with a left-handed proclivity: desks and spiral notebooks pose a constant battle, scissors are all but impossible to use and–according to some studies–life-expectancy might be lower than for right-handed people.

 

left-handed-611
The 44th President of the United States, Barack Obama is left-handed, as well as at least six former presidents.

 

What makes humanity’s bias against lefties all the more unfair is that left-handed people are born that way. In fact, scientists have speculated for years that a single gene could control a left-right preference in humans. Unfortunately, they just couldn’t pinpoint exactly where the gene might lie.

A group of researchers has identified a network of genes that relate to handedness in humans. What’s more, they’ve linked this preference to the development of asymmetry in the body and the brain.

HYPOTHESIS: If handedness is genetic and if right-handedness is such a dominant trait, why hasn’t left-handedness been forced out of the genetic pool? In reality, the research suggests that handedness could be more subtle than simple “dominant” or “recessive” traits–a whole host of genes might play significant roles.brain.png

What’s especially exciting is that these genes all relate to the development of left-right asymmetry in the body and brain, creating a strong case for the correlation between the development of this symmetry and the development of handedness. Disrupting any of these genes could lead to serious physical asymmetry, like situs inversus, a condition where the body’s organs are reversed (heart on the right side of the body, for example). In mice, the disruption of the gene PCSK6, which resulted in serious abnormal positioning of organs in their bodies.

CONCLUSION: There is a genetic component to handedness, hundreds of different genetic variants, and each one might push you one way or the other, and it’s the type of variance, along with the environment you’re in and the pressures acting on you, which affect your handedness.
smithsonian

Advertisements