| Down to a Science |

Why Are Some People Lefties?

Being a lefty is pretty rare. Only around 10 percent of the population is left-handed

Hello kiddos,

This is Professor Mordy Maven, Thinker, Wonderer, and Figure-Outer of all things Science-ish. What that basically means is I try really hard to figure stuff out. I do the hard work so you don’t have to!

The strangest thing happened at lunch today. I sat down next to my good friend, Leib. When we both reached for our forks, we immediately banged elbows. Then it happened again. I noticed that this was happening because I was holding my fork in my right hand, while Leib was holding his fork in his left hand — which is very silly. Everyone knows your right hand is stronger and more accurate. Or is it? I mean it is for me, but maybe not for Leib. That’s when I realized I needed to understand:

Why do some people prefer their left hand over their right?

First thing you need to know is that being a lefty is pretty rare. Only around 10 percent of the population is left-handed. That means in every minyan there’s probably only one left-handed guy! What made him so special? Well, it turns out there’s no simple answer to that. In fact, even the smartest scientists aren’t exactly sure. It seems like it’s a result of a mix of genes, environment and just plain old chance. But before we explain all that, let’s take a look at the brain. (Not your brain, silly! You can’t actually see your brain. Just, you know, let’s learn more about brains.)

You’ve only got one brain, but it’s actually divided into two halves. This is called brain lateralization. Just like we have two arms, two legs and two nostrils, we have two parts of the brain. The two parts do different things. The left side of the brain (or the left hemisphere) controls the muscles of the right side. And the right side of the brain (right hemisphere) controls the movements of the left side. Criss-cross, applesauce!

So, a person who uses their left hand more often, like for writing, eating and brushing their teeth is actually using the right side of their brain to do it! (Sorry guys, seems like whether you’re a righty or a lefty you still have to brush your teeth.)

But why does this happen? Some of it is probably because of your genes. (Not your jeans! Your genes!) Genes carry the information that is passed down to you from your parents, like your features or other characteristics. Based on the fact that left-handedness seems to run in families, it’s probably something that’s inherited. But that’s not so clear either. Only about 25-30 percent of lefties are born into lefty families. Most lefties don’t seem to have lefty genes at all. Some scientists think that it’s a learned behavior, meaning something you learn to do from watching the people around you. (Like how to dance the kazatzka or yodel.) But that doesn’t make much sense either. Especially since scientists have discovered that babies are already lefties or righties before they are even born! Using ultrasound pictures of unborn babies, they were able to see that some use their right hand and arm more often and others seem to prefer to move their left. So, um, we don’t exactly know.

But is it good to be a leftie? Sure, it’s good. It’s all good, guys. In fact, some people think it’s really, really good. There’s been research that suggests that the right side of the brain (and remember, the right side of the brain controls the left side of your body) is where creativity is based. Because of this, many people think that lefties are more creative.

(That might explain why Leib the lefty was swirling ketchup into his mashed potatoes. It definitely looked very creative.)

The idea is that people who are left-brained (like most righties) are very logical and good at figuring things like math and science, and people who are right-brained (like most lefties) are more artistic and creative. But, well, that’s not entirely true either.

Wait, why not? It sounds like a great theory! Right brain, left hand. Left brain, right hand. Simple, right? Yeah, but you’re forgetting about a little thing called the corpus callosum. (What’s that, you say? You didn’t forget about the corpus callosum because you never knew about it in the first place? Okay, well, that’s true too.)

The corpus callosum is the structure that connects the two sides of the brain. Through this connection, the two sides of the brain are actually able to work together and send information from one side to the next. So, nobody is really only using one side of their brain. We’re all using all of our brains all of the time. That’s why lefties can be perfectly logical and righties can be totally artsy!

This has all been very confusing! And it doesn’t help that Leib keeps banging my elbow. I’m discovering that science doesn’t have the answer to everything about lefties. But what we do know is that some people prefer using their left hands and most people prefer using their right hands. What we don’t know is — why?

I guess this is one of those cases where we have to be satisfied with knowing something but not everything. (Funny, when I brought home my test recently, my mother was not at all satisfied. Even though I knew something, just not everything!)

Basically, lefties are people who use their right brain to move their left side and are really good at making art out of mashed potatoes.

Here are some fascinating facts about lefties that you might like to know:

It’s not only humans who are righties and lefties. Chimpanzees, polar bears, and some other animals also seem to prefer one hand over another when using tools or looking for food.

Some people have a fear of left-handed people. It’s called sinistrophobia.

Lefties adjust to seeing underwater quicker than righties. Good to know if you’re scuba diving!


(Originally featured in Mishpacha Jr., Issue 873)

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