What Causes Some People to be Left-Handed?



What Causes Some People to be Left-Handed?

Researchers who study human hand preference agree that the side of the preferred hand (right versus left) is produced by biological and, most likely, genetic causes. The two most widely published genetic theories of human hand preference argue that evolutionary natural selection produced a majority of individuals with speech and language control in the left hemisphere of the brain. Because the left hemisphere also controls the movements of the right hand–and notably the movements needed to produce written language–millennia of evolutionary development resulted in a population of humans that is biased genetically toward individuals with left hemisphere speech/language and right-hand preference. Approximately 85 percent of people are right-handed. These theories also try to explain the persistent and continuing presence of a left-handed minority (about 15 percent of humans).

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Tree by Audrey Servillon (3AD-7)


There are kids up in the tree,

Day and Night they don’t eat,

I wonder where their mommy went,

Imagine the times they could have spent


They’re all just simple,

Cute and they have dimples,

I wonder why their mommy left,

If that was me, I couldn’t bear that in my chest


The storm is coming,

Viscous and astounding,

But the kids are still playing,

Their happiness left my saying,

‘Oh my God, why are they still playing,

They better start running’


Beyond is the massive flood,

They should hurry before they get stuck in the mud,

I screamed as if I wasn’t in the 17th floor,

But my voice didn’t reach the ground floor


I cry from what I see,

Little children died with the tree,

If only the tree was strong,

Nothing would’ve gone wrong

(Sir this is the poem I created since I didnt join the contest)