Nearly 200 studies involving more than two million people conclude that one in ten humans are left-handed. In the U.S. alone, that’s more than 33 million left-handers living in our very right-handed world.
Dogs and cats are left-handed, too – actually left-pawed
Experts don’t like to say pawed. They say animals have a left-handed limb preference, which covers all the living creatures, paws or not. This left-side preference is roughly four times higher in dogs and cats than it is in humans. Chimpanzees favor their right hands for tasks requiring strength and their lefts when fine motor skills are needed, such as the well-known termite-fishing-with-a-stick.
Psychology Today reported on a study involving 119 different animal species
Scientists found a limb preference for tasks requiring fine motor skill tasks in half of them, including octopi. Octopus experts say tentacle preference is matched by eye preference. No word yet on squid.
Is this left- or right- handedness one of those nature or nurture things?
A study of 25,000 twins (that’s one hell of a control group) found only one-fourth of the variance in handedness was genetic (nature). The rest is determined by gender, birthweight, mother’s age (but not her smoking), family life, and the world around them (nurture). This trait has been widely studied by many scientists. All the inherited estimates cluster around about 25%. This surprised me — I thought it would be more.
As an adjunct professor of the behavioral sciences
I knew that the child’s environment is really important, but not that much until I began to find things like Middle Eastern tribes that still believe the left hand is unclean. People camelling and donkeying around remote deserts always used the left hand to clean themselves after defecating. It’s easy to see that everybody would be right-handed, especially at meals.
Parents, religious figures, and teachers forced many left-handed non-nomads to train their right hand to be dominant because “the devil is left-handed” or so they’ll be like “normal people.”
Forced conversion negatively affects children’s cognitive development, so knock it off
The best solution encourages children to use both hands for all things and allowing them to choose which hand to use in what situation. Ambidextrous kids do well on many measures and are able to adapt to a right-handed world in ways corrected left-handers cannot. As Yogi Berra is reported to have said, “Mickey Mantle can hit just as good right-handed as he can left-handed because he’s naturally amphibious.”
Our preferred hand is the one with the best fine motor skills
Fine motor skills aren’t just dandy, too. They’re the very small and precise movements we make with our hands and feet, fingers and toes. Our handedness preferences are most obvious when we write, when we eat, and when we throw things.
The motor part of our motor skills
The motor is made up of all the small muscles that coordinate our hands, fingers, and eyes as we perform specific tasks, such as threading a needle. Most of us know this as eye-hand coordination. And no, kids, millions of hours of video games will never develop fine motor skills on their own. It’s the variety of tasks we perform every day that allow us to build those skills. Many apes have excellent eye-toe coordination. Do you?
How soon can you tell a child will be left-handed or right-handed?
The first time I saw a demonstration, a pediatric physician said handedness in toddlers can be predicted with ninety percent certainty by having them kick a ball several times. But there are ways to know handedness earlier.
If you’ve been around infants, you can write your own list of things of things they do as they develop into toddlers. Babies placed on their stomachs turn their heads in the same direction as their handedness. Everyone’s amazed the first time a squinting, sputtering, wrinkled creature squeezes our big fingers with their tiny ones. It’s not long before they’re putting everything in their mouths, banging things until you claim insanity, pointing, scribbling with crayons, and turning doorknobs. Keep an eye on that pet door.
But infancy isn’t where it starts, either
Studies show hand preference among thumb-sucking fetuses, indicating that handedness is probably established before babies are born. In support of that premise, when one or both parents are left-handed, they produce twice as many left-handed children than the all-rights.
Right-handedness is more practical in our right-handed world
My first recognition of how awkward life could be for left-handers was in the first grade when all those little sidearm desks were made for right-handed kids. The two left-handers in Miss Cooper’s class had to contort themselves into uncomfortable positions to be able to write. If you’re right-handed and come across one of those little half-desks, sit down and become a left-hander for a moment. While you’re experimenting, try using your left hand to cut things with your right-handed scissors.
Do certain professions have more left-handers than others?
Baseball and many other sports have lots of lefties and southpaws. According to enviroliteracy.org, music and art have more than their statistical share of left-handed people. So do architecture and mathematics. One group of scientists believes it’s not so much the specific job. Instead, they say it’s what those professions have in common that draws left-handers to them. All of those areas reward those with high levels of creativity, adaptability, and spatial awareness.
Some studies show lefts score higher on verbal reasoning and are more likely to be in accelerated programs for gifted students. In a possibly related statistic, 20% of Mensa members are left-handed, twice the rate for the population at large.
What are the downsides for lefties?
It’s a long list. Research indicates that left-handers are more likely to become delinquents and alcoholics. Lefts are more likely to have delusions, hallucinations, mood swings, and associated disorders. They are also more likely to have Crohn’s disease, ulcerative colitis, allergies, and asthma. More lefts are dyslexic and autistic, too. Rain Man was a very good driver. Was he also left-handed?
The best thing the left hand has going for it is the vena amoris
Known as the “lover’s vein,” it was believed to connect the fourth finger of our left hands directly to our hearts, also on our left. In 1686, an English lawyer named Swinburne specialized in matrimonial contracts. He stated that as the bride and groom give their hands to each other, so do they give their hearts on the other end of that vein.
Did you know the ring finger was for a time referred to as the “leech finger” because it was used for bloodletting?
Do we have dominant eyes, too?
Our left and right eyes look at the same things at the same time, but are just far enough apart that they see them from slightly different angles. Our brains combine the two nearly-alike images into one three-dimensional image. Cleveland Clinic says the dominant eye is the one that our brain prefers, so it’s the one where our attention goes. If something catches the side of your eye and you turn to see it, your dominant eye was doing the driving. Whatever we look at, our dominant eye feeds information to our brain while our passive eye goes along for the ride.
You can identify your motor-dominant sighting eye in less than one minute, right now, wherever you are, with this version of the Miles test:
- Pick a small object far away from you.
- Extend your arms out in front of you.
- Create a hole by bringing your thumbs and forefingers together until the tips touch, leaving just a small opening.
- Extend your arms out in front of you.
- Look at the object through the hole you made,
- Close your left eye. If you can still see the object through the hole between your fingers, your right eye is probably dominant. If you don’t still see the object after closing your left eye, then your left eye is probably dominant.
- Do this several times and see which is your motor-dominant eye. It is twice as likely to be your right than your left.
When our eyes see slightly different things, our brains act differently
When the images don’t match, our brains don’t combine them. Each eye takes over in turn, and they alternate as our brain tries to work things out. This alternating signals from left and right is called binocular rivalry.
The binocular rivalry test sounds like a contest between Bushnell and Zeiss, but isn’t
Over at binocularrivalryonline.com, you’ll find a website that was “created to enable binocular rivalry testing in the comfort and convenience of an individual’s own home.” I don’t know what you do if you don’t own a home.
Marty Feldman had a lazy eye
I was told that in some places, a lazy eye is called a London Paree because one eye points toward London while the other points at Paris.
Bonus
Rocky won because he was a southpaw. Right-handed boxers like Apollo Creed find lefties hard to fight because everything is backwards. Mick said it was the only way that Rocky had a chance.
