What makes someone right-handed vs. left-handed? There are no clear answers, but there is growing evidence that left-hand dominant people tend to be more creative and divergent thinkers. Are you a lefty, or a righty? The genetic, biological, and environmental forces that determine handedness continue to intrigue and baffle scientists.
Neuroscientists know that left-handed people tend to be more "right-brained" and use the right hemisphere of their cerebrum to a greater degree than righties, and vice versa.
Being right brain dominant may present advantages, but the ultimate goal is to have an equal balance and symmetry between all four brain hemispheres. Lefties have more brain symmetry than righties. Brain symmetry between all four hemispheres makes you more likely to be a champion and leader.
August 13th is annual International Lefthanders Day. Why would there be a day dedicated to being a lefthander? Left-handed people make up only 10% of the population and are underdogs in a world designed for right-handers that 90% take for granted as being the status quo. The inherent bias against lefties has a long and stigmatized history. Ironically, being a lefty may actually provide an evolutionary biological advantage.
The Language Bias Built Into Handedness: Sinistral vs. Dexter
The etymology and connotations of most languages implies that lefties are not only clumsy and "less than," but "evil" and "wrong." The Latin words "sinistral" (left) and "dexter" (right) are based on the same root for sinister and dexterous. In scientific terms, 'sinistral' means left-handed and 'dextral' means right-handed.
In Greek, ‘skaios’ means both left-handed and awkward, and possesed by an omen. In Hindi, the word for left-hand is ‘Ulta Haanth,’ which literally means “the wrong hand.” In French, the word for being a lefty is ‘gauche,’ which is synonomous with being clumsy. On the flip side, the French word ‘droit’ means right and lawful. In German, the word “recht” means both right-handed, and “the law” and it also means “correct,” while “links” means both left-handed and "weak.”
Left-Handed People are More Likely to be Champions and Leaders
Environmental forces and neurobiology combine to make lefties predisposed to be trailblazers and iconoclasts. One of the benefits of being a black sheep is that it forces you to avoid a herd mentality and to stay nimble and adaptable by constantly flexing your creative and divergent thinking abilities.
If you have a genetic disposition to be a lefty—odds are that growing up in a right-handed world will make you more likely to think outside-the-box and become a leader. It’s ironic that for centuries teachers and schools would literally tie the left-hand behind a student's back in an attempt to force pupils to be right-handed. Luckily, science is proving that allowing one’s biological handedness to flourish leads to success and leadership skills.
Five of our last seven American presidents — Gerald Ford, Ronald Reagan, George H. W. Bush, Bill Clinton, and Barack Obama — have been left-handed. Technically, Ronald Reagan is often cited as being ambidextrous, and Gerald Ford wrote with his right hand while standing but used his left hand while sitting.
The fact that Gerald Ford was more inclined to be left-handed while sitting but not while standing is interesting from a neuroscientific perspective. My educated guess would be that this has to do with the role that the cerebellum plays in proprioception, cognition, and balance as related to right-brain, left-brain function while writing or signing your name vs. playing sports.
The left hemisphere of the cerebellum (down brain) controls the left hand, and the right hemisphere of the cerebrum (up brain) also controls the left hand. It crosses over, and is confusing, I know. The more I think about it the more spastic my typing becomes . . . Lefties have a dominant left cerebellar hemisphere and dominant right cerebral hemisphere. Because of this lefties have more symmetrical brain function between hemispheres.
In neurological terms left-handers tend to be right-hemisphere dominant. The cognitive and physiological vantage point of lefties is different from righties which makes their play unpredictable on and off the court. A lefties ability to surprise and catch a right-handed competitor off guard in sport and battle extends to the intellectual battlefield, too.
Philosopher Walter Benjamin once said, "All the decisive blows are struck left-handed." There appears to be disproportionate presence of left-handed players in hand eye coordination sports such as tennis, baseball, ping-pong, and hockey. Famous military leaders like Alexander the Great and Napoleon were lefties and were able to outwit the enemy through surprising strategies of war.
The athletic advantage of being left-handed is regularly displayed on the tennis court. It’s no coincidence that two of the greatest tennis matches ever played at Wimbledon were between a lefty and a righty. In 1980, John McEnroe (sinistral) went up against the right-handed Bjorn Borg (dextral) in one of the most legendary tennis matches of all time.
And, in 2008 – in what many view as “The Greatest Tennis Match of All Time” – Rafael Nadal (lefty) defeated Roger Federer (righty) at Wimbledon. For some great vintage tennis footage and images of brilliant left-handedness in action (and for a playful interview with Borg and McEnroe) please watch this BBC Wimbledon video.
The Science of Handedness Remains a Mystery
Brain asymmetry exists in all our primate cousins. Researchers remain perplexed as to why the human brain seems to be more asymmetric than the primate brain and why the ratio of right to left-handedness in humans is 9-to-1. Primates are evenly split 50-50 between left and right handedness.
More research needs to be done to unravel the mysteries of asymmetry between all four hemispheres of the human brain. The more we are able to understand how all four brain hemispheres work in concert, the more coaches will be able to maximize human performance and improve leadership skills.
Being left-handed runs in families. Whether you are inclined to be left or right dominant correlates to asymmetry between the hemispheres of your brain as it correlates to motor skills and cognitive functioning. “This is really still mysterious,” according to, Clyde Francks, a geneticist and the lead author of a paper on title the “Gene for Left-Handedness is Found.” Francks said of how brain asymmetry leads to left or right handedness, “this is not at all understood; we’re really at the very beginning of understanding what makes the brain asymmetrical.”
Dr. Daniel Geschwind, a professor of human genetics, neurology and psychiatry at University of California, Los Angeles says that left-handers have more symmetrical brains, with more even distribution between the two hemispheres. “Perhaps a more accurate conceptual way to think about them is as non-right-handers,” he said. “Many of them are much more likely to be ambidextrous and have fine motor abilities with their right hands.”
Geschwinds adds, “Handedness has a genetic basis, but like other complex traits — height, weight — it is complex,” he said. “It’s not a single gene that leads to it. There’s a strong environmental component, too. It’s a very tricky problem.”
Overcoming the Odds: Lefties Must Struggle for Peak Performance in a Righty World
My father was a right-handed neurosurgeon and tennis player. He was also a neuroscientist who was fascinated with left-brain, right-brain function of both the cerebral and cerebellar hemispheres. My dad practiced at hospitals that taught neurosurgery and was well aware of the added strain that his left-handed residents and surgeons experienced in the operating room.
The authors of a study titled “The Loneliness of the Left Handed Surgeon” from New York’s Memorial Sloan-Kettering Cancer Center and other institutions, say that left handed surgeons feel that they are an unorganized minority. Their survey found that only 13% of left-handed surgeons were provided with left handed instruments while training.
The report found that also found that there is a lack of laterality related mentoring for left-handed surgical residents: "There are no studies or teaching material available to teach left-handed surgical residents. Laterality-related guidance was reported to be minimal in medical school.
The researchers concluded, "Nearly half of the left-handed surgeons surveyed were anxious about their laterality related difficulties and sought advice during surgical residency, but only one in 10 programs mentored for laterality predominance. Provision of a left-handed mentor and other environmental modifications could be used to minimize the recurring difficulties for left-handed learners.’’ Again, this is another reason that August 13th is International Lefthanders Day. Making the world more ambidextrous and "lefty friendly" will benefit us all.
"Having basic sets of left-handed instruments (scissors, clamps, and needle holders) available in the teaching hospitals for medical students and surgical residents may minimize the inconveniences associated with learning," the authors concluded.
Conclusion: Engage Both Hands to Maximize Brain Function and Performance
As with most human traits, handedness falls into a spectrum that spans from some who are very strongly right-handed and those who are very strongly left-handed, while most of us probably fall in between.
We are all inclined to be more right or left-handed, footed, eared and eyed. This split-model between our bodies and brains offers many potential ways that you can make daily lifestyle choices that flex all four hemispheres and create maximal brain symmetry.
I am currently fine-tuning a practical daily prescriptive plan for The Athlete's Way that will help create symmetry between all four brain hemispheres regardless of handedness. That said, if you are a righty, it might be to your advantage to consciously begin using your left hand and ear more regularly while speaking and listening on your phone. And, use your left index finger when texting, if you're a righty.
If you'd like to learn more, I offer some practical tips on creating brain symmetry in a previous Psychology Today blog titled: “Squeeze a Ball With Your Left Hand to Increase Creativity.”