The science of handedness
Jalen Brunson and the lefty advantage in sports
A few years ago, there was a pitcher in the Yankees organization named Pat Venditte.
Readers of this newsletter might remember Pat Venditte. It’s hard to forget about him, considering his unique ability. He was the only pitcher in professional baseball who threw with both arms.
Venditte touched the upper 80s with a slider and a curveball with his right arm, his naturally dominant arm. With his left, he threw sidearm in the mid-80s with a slider as well. I recall he used a custom, six-fingered glove that could be worn with either hand, although MLB would later adopt a rule (the “Pat Venditte Rule”) requiring that ambidextrous pitchers must not switch throwing arms in the middle of an at-bat. The back-and-forth with a switch hitter was delaying the game.
A general manager’s dream: Two pitchers for the price of one.
Venditte was a unique attraction, and a fascinating case study, but he struggled to get beyond the gimmick. His velocity was pedestrian; any advantage he gained by being able to face same-handed hitters was negated by ultimately mediocre stuff. It was a shame, too, because being the only professional pitcher doing it, Venditte seemed to represent the “ceiling” of what a switch pitcher could offer.
Until now.
There’s a pitcher for the Mississippi State baseball team named Jurrangelo Cijntje who throws 99 MPH with his right AND throws 95 MPH with his left arm. He has an 8-1 record and a 3.48 ERA in 14 starts this season for the Bulldogs, who are ranked 14th in America.
According to MLB.com, Cijntje (pronounced SAIN-je) grew up in Curacao, where he started playing baseball with both hands at age 6. He is naturally left-handed but says he writes with his right arm and often eats with his left. For a while, he pitched primarily as a righty, because he also played catcher and shortstop — two positions that favor right-handedness. In high school, when it was discovered how strong and accurately he could still throw with his natural arm, coaches began to work with him on throwing with both.
With all due respect to Shohei Ohtani, I’m more impressed by a switch pitcher who can dominate hitters with either arm. And here’s why.
Handedness
The origins of human handedness trace back 7 million years or so, and all the theories about why are understandably fuzzy. The story I like most is almost certainly apocryphal. In the early days of our bipedal existence, females did most of the work (some things haven’t changed). They were the principal hunters of the group, and they were often toting babies around, too. Because females carried the babies in their left arms, cradling the head against the woman’s chest and heartbeat, it freed up the right arm for throwing projectiles at prey. Over time, right-arm throwing accuracy conveyed a competitive advantage, producing more right-arm dominant offspring. Eventually, one of these offspring would turn into Nolan Ryan.
I don’t know! It’s a nice theory, and it does help to explain one thing: why humans are the only species to express a strong affinity for one arm vs. the other.
This affinity runs deep. A study of the wear patterns of Neanderthal teeth suggested that 88 percent were right-handed. A survey of cave-dwelling artwork dating back 5,000 years showed a clear preference for the right hand. Babies almost always suck the thumb on their right hand in the womb. As I wrote about in my book, in the early 20th century in London there was an Ambidextral Culture Society that formed as a progressive rejection of handedness and an effort to promote “balance” and “flexibility.” Members learned to play piano with one hand and write with the other. But eventually, the whole thing grew tiresome.
That’s not to say handedness cannot be acquired. There is considerable debate about how much of handedness is actually inherited. About a quarter of monozygotic twins — those who share the same genes — actually differ in their handedness. That fits with a 2020 meta-analysis (a study that collects research from a multitude of other studies) on human handedness led by Marietta Papadatou-Pastou, which placed the heritability of handedness at about 24 percent.
Handedness may also be a reflection of our environment, and the societal pressures that force us (directly or indirectly) to choose one side or the other. Papadatou-Pastou notes that left-handedness is much less common in Asia; specifically, less than 1 percent of children in China are left-handed. “This is most likely due to differential cultural pressures,” she wrote.
Chris McManus, who wrote the book, “Right Hand, Left Hand,” based off decades of his own handedness research, has found that the prevalence of left-handedness in society has experienced profound ebbs and flows over the years, dipping below 4 percent in the 1890s and early 1900s and surging above 10 percent in the late 1940s and 1950s. McManus ascribes these historical shifts to social influences that then lead to genetic differences. At certain times — such as during the Victorian era — left-handers were bullied or ostracized or forced to conform to the more “dignified” right-handed ways (a lot of mythology associated lefties with the devil - “sinister” means left in Latin). This might have made left-handers less likely to marry and produce offspring to continue their left-handed lineage.
Indeed, at the end of the nineteenth century, McManus found that left-handed couples had fewer children than right-handers. Nurture influenced nature.
Hook and lateral
The brain is divided into two hemispheres, the left and the right, and their responsibilities are generally believed to run contralaterally: i.e. the left brain controls the right hand. You’ve probably heard folklore about the polarization of the brain and which side is more “analytical” vs. “creative,” but I’m going to sidestep that rabbit hole (other than to say that the myths and simplifications tend to stray from neurological facts).
Brain lateralization, however, might be able to help explain one question that often comes up in sports: Why are more athletes left-handed?
The Papadatou-Pastou meta-analysis found that 15 percent of “sporting elites” were left-handed, compared to 10 percent of the general population. I honestly don’t know what she included as a “sporting elite,” but anecdotally there seems no question regarding the prevalence of left-handers, particularly in sports like baseball and hockey. The most common explanation is that being left-handed wields a tactical advantage: lefties get more opportunities to practice against right-handers than right-handers get against lefties.
Consider someone like Jalen Brunson, the crafty guard who dazzled for the Knicks this postseason. His left-handed shooting motion may well endow him with a split-second advantage over defenders more accustomed to blocking shots from the opposite side. The majority of NHL players actually shoot left-handed, primarily because Canadian players were taught that way to better control the stick (more Canadian golfers also swing left-handed - but it doesn’t actually mean they are natural lefties).
And perhaps there is something else going on. A study by Florian Loffing in 2017 took a closer look at the data. It’s not just that lefties are more prevalent in elite sports. But they are far more overrepresented in time-pressure sports, such as baseball, cricket, and table tennis. In these activities, the percentage of left-handers increased to more than 30 percent. Left-handedness is more common in table tennis than in all the other racket sports (tennis, badminton, and squash) combined. “Achievement may depend to a larger extent on basic physiological and psychological aspects (e.g. agility, concentration, emotion regulation) irrespective of an opponent's laterality,” Loffing wrote.
What “physiological and psychological aspects”? Well, the right brain has been linked to visuospatial processing and deemed by some to be more “visually intelligent” than its counterpart. Numerous studies on elite athletes have noted differences in activations and grey matter in brain regions like the right insula, right fusiform gyrus, right cerebellum, right hippocampus, and others.
Whether or not any of these findings can be neurologically linked to better time-pressure performance in sports with the left hand, I don’t know. I’ve yet to come across a study that explores this. But Loffing’s data would suggest something is going on.
It almost goes without saying that ambidextricity is easier to impress upon a child who is still developing, much like it’s easier for a kid to learn a new language than an adult. Their brains are still forming; their neuroplasticity, to use the technical term, is much more robust. It’s not a surprise that the pitcher Cijntje started using both hands at age 6. Whether “switch pitching” confers an advantage for him, or not, remains to be seen.
Lefties and righties
Regardless, we are more bimanual than we often think.
In the 1980s, French psychologist Yves Guiard looked closely at handedness and concluded that performance asymmetries were probably overstated. In most tasks, even writing and eating, we may have one arm that we use repeatedly, but that doesn’t mean the other one is useless. While writing, Guiard showed, the nondominant hand often plays a covert role adjusting the paper in anticipation of the other hand’s pen movements.
“If we think of a violinist,” Guiard wrote, “it is rather obvious that neither of his or her hands is dominant in any clear sense: Each of the two manual roles (grossly speaking, manipulating the violin, manipulating the bow) is crucial and difficult.”
As I type this, I’m coordinating both sets of fingers simultaneously. Driving occupies two hands (hopefully). But even in tasks involving a dominant hand, Giuard observed, the nondominant hand is almost always involved in “framing” or “stabilizing” the activity. Think of cooking or cutting with a sharp knife. This stabilizing action actually typically begins “before the action of the other member of the pair,” Guiard wrote. In this sense, the hands work as a partnership. Said Guiard: “The left hand knows what the right hand is planning, and the right hand knows what the left hand just did.”
Work by neuroscientists Fred Dick and Joern Diedrichsen at the University College London confirms this theory — and goes even further. In one study, the researchers took a group of expert violinists from the Royal Academy of Music and had them play the instrument inside an fMRI scanner. Except the instrument they were asked to use was the exact opposite of what they’d been trained on. A righty, for instance, was given a reverse violin that required that the bow be swung with the left and the strings to be manipulated with the right.
The violinists initially reacted quite angrily, the researchers told me. “They said, ‘No, I cannot possibly do that!’”
As it happened, though, they actually could. In fact, after a little bit of time, they could play their opposing instrument quite well — even faster than novice violinists using their correct hands. It seems that, from all those years of practice, the brain was soaking up a lot of information about what both hands were doing. When pressed to perform, it was able to transfer that information across the neural hemispheres without a huge gap in ability. [The study by Dick and Diedrichsen got held up after Diedrichsen left UCL, but hopefully they can publish it someday]
Another (possibly apocryphal) story before wrapping this up. Larry Bird was coaching the Indiana Pacers when they drafted a high-school phenom named Jonathan Bender. Bender - being a young hotshot - wasn’t familiar with Bird’s legend, so he challenged him to a game of one-on-one. Bird, even in retirement, won easily.
Afterwards, Bender said to Bird. “Damn, I didn’t know you were a lefty.”
Bird shrugged and winked.
Links
NBA teams’ performance shifts with time zones … Lessons from Sports Psychology Research … Players of the NBA G League donned wearable technology daily during training to conduct biomechanical, kinematic and force-producing assessments … Elite runners live longer … 6 Olympic athletes reveal how they’re preparing for the Paris Games … The most lavish ultra-marathon ever … How to motivate mentally well athletes … How do the world’s best athletes handle pressure? … A high velocity usage tax: A proposal to protect pitchers … Cold plunges may reduce muscle growth … Mouth rinsing carbs may improve performance in Romanian deadlift … Olympic Dodgeball
References
Corballis MC. Left brain, right brain: facts and fantasies. PLoS Biol. 2014 Jan;12(1):e1001767. doi: 10.1371/journal.pbio.1001767. Epub 2014 Jan 21. PMID: 24465175; PMCID: PMC3897366.
Guiard, Yves. "Asymmetric division of labor in human skilled bimanual action: The kinematic chain as a model." Journal of motor behavior 19.4 (1987): 486-517.
Loffing, Florian. "Left-handedness and time pressure in elite interactive ball games." Biology letters 13.11 (2017): 20170446.
McManus, Ian Christopher. "The history and geography of human handedness." Language lateralization and psychosis (2009): 37-57.
Papadatou-Pastou, Marietta, et al. "Human handedness: A meta-analysis." Psychological bulletin 146.6 (2020): 481.
I have had several conversations with others both inside and outside the sport of water polo about handedness in which I postulated that water polo is a sport where being a left handed player conveys more advantage than almost any other sport.
In water polo, the advantage in passing and shooting that a left handed player has on the right side of the playing field (especially in extra player situations) is indisputable. At the elite level, it is almost impossible to be a top team and especially to be a top team in extra player situations without an elite left handed athlete.
So at least anecdotally in the sport I'm most familiar with, there is likely a much higher incidence of left handedness at almost all levels because of strong selection and developmental bias among coaches.
Great stuff.
Two thoughts: 1) When I broke my right thumb during football practice my senior year of high school, I attempted writing with my left hand in school. Didn't work. I was better off manipulating the pen with the cast on my right hand.
2) My wife is a lefty and proud of it. I passed along the Seinfeld joke about how refernces to lefties are so often derogatory. Such as the expression "he has two left feet." And, "What are we having for dinner? Left-overs." And, "Where did everybody go during that performace? They left."