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No one has ever gotten it quite right about lefties.
For decades, they were seen as consorts of the devil. The Latin root for left, sinistre, means exactly what it looks like.
Then scientists discovered that the right hemisphere of the brain (which controls the left hand) is associated with creative thought. Suddenly southpaws everywhere were elevated to super-genius status.
You couldn’t swing a pair of left-handed scissors without hitting a list of famous lefties: Michelangelo, Joan of Arc, Julius Caesar, Napoleon and four out of the last five US presidents. Then there’s the celeb roster: Julia Roberts, Peter O’Toole and Marilyn Monroe, to name but a handful.
Now researchers are rethinking both stereotypes, digging deeper into what makes left-handedness such a rare and yet persistent trait.
What they’re finding is that lefties might not be any more evil or brilliant than the rest of us. But their brains could yield insight into ways to foster human creativity — as well as new understandings about disorders such as schizophrenia and ADHD.
When it comes to divergent thinking — the ability to not only think outside the box, but to come up with interesting uses for whatever is in the box — it seems that being “right-brained” or “left-brained” doesn’t matter that much. Instead, researchers are now focusing on an apparently stronger association between creativity and brain symmetry, the rare phenomena in which neither side of the brain is dominant.
Symmetry is only subtly more pronounced in lefties, with an even greater percentage of ambidextrous people showing both hemispheres firing at once.
“I don’t think we really know if left-handers are really over-represented among high achieving groups, relative to their frequency in the population,” said Dr. Clyde Francks, the lead researcher who discovered a gene associated with left-handedness while at Oxford University.
Francks, now a senior investigator with the Max Planck Institute for Psycholinguistics in the Netherlands, today is looking for genes that affect brain asymmetry.
“When we have found some more genes, we can test them in relation to these kinds of creativity measures, to try to tease out subtle links,” he said.
“Roughly 90% of people are right handed and virtually all of them have left-hemisphere language dominance. Among left-handers, still around 70% have left-hemisphere language dominance, but around 30% have more symmetrical or else a reversed pattern of right hemisphere language dominance. So the link between handedness and language lateralization is certainly there, but it’s subtle,” he said.
Lefties’ smarter-than-though status that was bolstered in 2007 with Francks’ discovery of the gene, LRRTM1, associated with left-handedness. The old notion that lefties were consciously choosing to bump elbows with the rest of us at the dinner table was finally laid to rest, as the sinistral singer Lady Gaga might put it: Baby, they were born this way.
Before that, scientists who studied left-handedness used to focus on the negative — suggesting people with a left-hand preference were more apt to die young of a variety of accidents than their right-handed counterparts, for instance (more recent studies refute this).
Soon the scientific mood toward sinistrals shifted. Instead of fearing people who fail to switch their forks to their right hands after cutting into their steaks, scientific — and not-so-scientific — studies were conducted to determine why lefties are so smart, creative and intuitive.
But not all the research was glowing: both brain symmetry and the gene associated with left-handedness also is associated with schizophrenia.
And, while the left-handed gene helps explain why some people are lefties, it is not the only factor causing some people to smear ink across the page when they write. Left-handedness is thought to be around 25% inherited. So, it’s highly likely that environmental factors during fetal development might play a role.
Early studies suggested that maternal stress during pregnancy could elevate testosterone levels and cause an embryo’s hand preference to go south.
“Left-handedness probably arises from a whole mixed bag of different causes in different people,” Francks said. “We don’t really know the genes and processes in brain development that cause right-handedness in the majority of people. It follows that we don’t know how the processes are altered in left-handers.”
Francks said the discovery of other crucial genes will help researchers understand the processes involved in brain development for both righties and lefties.
“Finding genes involved in brain asymmetry should help to reveal the early processes in brain development that are affected by environmental influences,” he said.
So if environmental factors can contribute to someone becoming a southpaw, and if it turns out that left-handers really are more creative and brilliant than the rest of us (even if just slightly), can environmental factors influence the brain’s symmetry enough to coax ordinary children into becoming Michelangelos?
Maybe.
Dr. Psyche Loui, a neuroscience researcher at Harvard Medical School has been investigating the phenomenon of absolute pitch, the ability to name musical pitches without a reference. Her work has uncovered a link between brain symmetry in healthy adults and absolute pitch, and she said not all of the factors contributing to absolute pitch are believed to be genetic.
“The early onset of musical training seems to be a big factor, as is being of East Asian descent. Absolute pitch much more common in people who list tonal languages as their first language,” Loui said.
Before you teach your newborn Mandarin Chinese, keep in mind that it’s not clear whether those factors are incidental or whether they help “train” young brains to communicate more symmetrically. Similarly, sticking a pencil in your toddler’s left hand will not guarantee her the future presidency. But at least if she grabs it, no one will burn her at the stake anymore.