Posted on 03/06/2002 9:50:08 PM PST by PurVirgo
Rense.comPeople who grow up left-handed have a different, more flexible brain structure than those born to take life by the right hand, say researchers at the University of California, Los Angeles, who used twins to study heredity.
The reason is that right-handers have genes that force their brains into a slightly more one- sided structure, according to research published yesterday in the Proceedings of the National Academy of Sciences. Left-handers appear to be missing those genes.
"There really is a difference in brains that results in a more symmetric brain in left-handers, where the two sides are more equal," said UCLA neurogeneticist Daniel Geschwind, who led the research team. "There is more flexibility, and that is under genetic control."
In the effort to understand how the brain shapes the mind, researchers have been striving to document the way genes and environment affect intelligence and mental abilities. The human insistence on preferring one hand over the other poses a particularly nagging question that touches on both anatomy and behavior.
"There is clearly something fundamental here we need to comprehend if we are to understand what makes us uniquely human," Geschwind said.
Of all the primates, only human beings display such a strong predisposition to right-handedness. Right-handers make up about 90 percent of the population. The left and right halves of the brain are different in both their anatomy and their functions, related in part to hand preference.
But until now, no one could document the connection.
The UCLA study is the strongest evidence yet that heredity shapes the brains of left-handed and right-handed people differently, Dartmouth neuroscientist Michael Gazzaniga said.
The UCLA researchers conducted brain scans on 72 pairs of male identical twins between 75 and 85 years old.
Identical twins, who share the same genes, offer a unique lens through which to study the relative effects of heredity on human nature.
Right- and left-handedness is partially determined by genetics. If a person inherits the gene for right-handedness, that person will be right-handed. People who do not have that gene, however, can be either left- or right-handed. There is no specific gene for left-handedness.
Right-handers typically have a larger left brain hemisphere, where their language abilities are concentrated.
Conversely, left-handers have more balanced brains, with both sides relatively symmetrical. The language abilities of left-handers more often are concentrated on the right side.
If identical twins carry the gene for hand preference, both must be right-handed. If they lack the gene, one twin can develop right-handed while the other develops left- handed.
The researchers found that the brains of identical right-handed twins were very similar in size and structure. But when a left-hander was part of the twin set, the brains were different. The conclusion, researchers said, is that the absence of the gene for hand preference allows the brain to develop differently as the individual grows up.
A similar pattern did not appear in 67 sets of fraternal twins used as a control group.
But I wouldn't have dreamed of it.
The teachers I had in those days were magnificent.
Come to think of it, so were we students.
Err, with one exception.
As are George H.W. Bush and H. Ross Perot. There was comment in the 1992 election that all the candidates were left-handed.
Every skill that other people have taught me, I copy them and do it righthanded (knitting, crochetting, bowling, batting a ball) but all things I have picked up on my own, (eating, writing) I do lefthanded. No wonder we lefties are confused!! Sometimes, I even have to stop and think which hand I want to use, and I have been "practicing" for seventy years.
Nope. EXTREMELY "left-eared". I spend a lot of time every day on a phone, and to hold one up to my right ear feels incredibly awkward and uncomfortable.
It's amazing how everywhere else in the world, people have always noticed the supposed correlation between left-handedness and increased intelligence, yet here on FR they're all claiming the exact opposite.
I can only hypothesize that they're all either ignorant or jealous. Or both.
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More than flexible. Some days if it weren't in its jar it would spread out like a puddle.
I've been known to flat-out lie and say,"I'm new to the area," when asked to give directions. Nothing makes me happier than to be asked directions in a place that I am really new to so it isn't a lie.
I don't really notice my being left handed as a handicap until I try to either mimic somebody's motions, or am presented with something like a top-bound binder. Those are really aggravating. And I can't write on a chalkboard very legibly.
You can always tell a lefty from a righty by looking at their hands - we always have ink or pencil smudges from going over our writing. Unless of course, I'm being creative and writing either backwards or with the paper nearly upside down.
Oh, I have a question - is the dominant hand supposed to be bigger than the other? I heard that somewhere, but my left hand is actually a bit smaller than my right.
Someone else also mentionned about learning how to knit or crochet...I remember once, my girlfriend was going to teach me how to knit...but she was right handed, and trying to do it the way she showed me was very awkward...so she tried to reverse it, to show me how to knit left handed...well, she ended up frustrated as she could not do it, so she finally threw her hands up and told me to go to a store which had knitting classes to learn....well, needless to say, I never did to, and never learned how to knit...
And I also remember when in grade school, we used ink pens that we had to fill from the ink bottles...and when a leftie writes with one of those pens, the ink is still fairly wet, and our leftie hands smear right over what we just wrote...I could never get a great mark in neatness in penmanship because of that...those teachers also did not seem to realize that our sloppiness was not of our own doing...
I must go with the notion, that we lefties, are highly intelligent, highly artistic, and just great folk...LOL...
I tried it, your theory did not work with me. I am a leftie, but my left hand was tucked. Like a lot of other lefties, I have a fundamental confusion about such things as which side of the plate to stand on when playing baseball, which way to swing a golf club, etc. I can write with either hand. I throw a ball with my left hand, a frisbee with my right. I shoot a rifle left handed, a bow right handed. I am "mouse-idextrous" and use a computer mouse with equal comfort in either hand. Wierd...
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