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Are you left-handed?
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If so, one in ten people around the world is like you.
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However, nine out of ten people are right-handed.
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[1. Human handedness starts in the stone age.]
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Stone tools suggest that most of our ancestors were, like most of us, right-handed.
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It's hard to pin down when left-handedness started, but we do have evidence that there were left-handed Neanderthals 500,000 years ago.
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How do we know this?
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Well, they were probably eating raw meat, which is tough old stuff.
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Archaeologists think the Neanderthals would sink their teeth in, and then use a sharp piece of stone to cut the meat near their mouth.
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Sometimes the stone slipped.
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And from the direction of the scratches, 10 percent of Neanderthals seem to have held the cutter in their left hand.
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[2. Left handers, your brains are more bespoke.]
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For right-handers, it's normally the left side of the brain that's associated with speech and language.
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What though if you are left-handed?
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Despite using their left hand for writing, two thirds of left-handers are just like right-handers, in having language in their left brain.
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But, a third of left-handers have language in the right side of their brain—the opposite of right-handers.
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Left-handers are much more variable in the ways their brains are organized.
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In contrast, right-hander's brains are off the peg.
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Left-handedness is therefore much more of a mixture of strengths and weaknesses, pros and cons coming from having a somewhat differently organized brain.
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Is your baby sucking its thumb?
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Psychologist Peter Hepper in Belfast studied several hundred scans where the baby in the womb was seen sucking its thumb.
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About 90 percent of babies sucked their right thumb.
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And at 12 years old, almost all of those right thumb suckers were right-handed.
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Whereas three quarters of the left thumb suckers would become left-handed.
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Genes are clearly also important.
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One left-handed parent, and you're more likely to be left-handed yourself.
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Both parents left-handed, and you're even more likely.
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About a one-in-four chance.
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Infants often go through a random chaotic phase where they use the right hand one day, and the left the other, perplexing their parents.
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By about two years old, their handedness is usually consistent.
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[4. We could all be a little more ambidextrous if we tried.]
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If you practise long and hard enough, then you can probably do anything equally well with either hand.
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Concert pianists are a good example, though it does take dedication.
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In 1797, the right-handed Admiral Lord Nelson, had his right elbow shattered by a musket ball.
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The arm was amputated.
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Within six months though, Nelson had learnt to write fluently with his left hand.
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But the motivation was there, of course.
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Professional sports players are also motivated to practice, as it can give an added edge in competition.
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Footballers train to kick well with either foot, and when practicing they use both feet confidently and well.
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But under pressure, when the action's hot, they often revert to using their dominant foot.
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Even if it means taking an extra half step before shooting for goal.
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Reversing your natural sidedness does come with a cost.
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You could be almost equally good with each hand or foot, but the price would be so much time practicing that you probably wouldn't do anything else with your life.
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[5. Many of those famous left-handers were actually right-handed.]
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The list of famous left-handers seems pretty impressive.
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Albert Einstein, Beethoven, Bob Dylan, Picasso, Neil Armstrong, Winston Churchill, Benjamin Franklin, Marilyn Monroe, all are claimed—on the Internet—to be left-handed.
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And in each case, it's almost certainly wrong.
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The evidence of left-handedness is often very dodgy indeed.
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For instance, there's a book with a painting of Beethoven writing with his left hand, the picture has clearly been flipped.
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There are many reasons why people may wrongly claim that famous individuals are left-handed.
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Tribal loyalty and the reflected glory of feeling part of the same handedness club are just two of them.
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Perhaps when it comes down to it, there is a little bit of the left-hander in each of us.