Being a southpaw – or someone who is left-handed – is quite rare. It is estimated that only 10% of all humans prefer to use their left hand over using their right hand. That’s a shockingly low number, especially since it is considered a preference.
Unfortunately, there is no definitive answer because, well, it’s been true for as far back as archeologists, historians, and anthropologists can tell. The best we can do is make some educated guesses.
How Most People Became Right-Handed and Why Some Didn’t
We do have a lot of data, evidence, and artifacts that can help create a few theories around this strange phenomenon.. Also, studying the people around them today helps experts to refine and review older theories.
1. A Closer Look at the Teeth
As strange as it sounds, dental remains provide a surprising amount of information about how long people have preferred to use their right hands.
When people started using tools, they found that two hands just weren’t enough. They resorted to using their mouth as their third hand.
Before you are too dismissive of our ancient ancestors, consider what you used to do (or perhaps still do) when you can’t get a water bottle or a bag of chips open? Our jaws are incredibly strong, making them a reliable option for the times when we need a bit more strength – not that teeth are a particularly good option. As we’re about to see, it can be pretty rough on our teeth.
Looking at teeth from people who were evolved enough to use tools, there is evidence of tools being used to cut objects. It is thought that people used their mouths to hold hides and other items that needed to be worked, such as when they were tanning a hide. Experts think that people held one end of the material with one hand, a tool with the other hand, and a second end of the material with their mouths. The marks in the remaining teeth indicate that the tool was brought up the material toward the end being held by the teeth, but the people didn’t always stop before hitting their teeth.
Of course, there are indications that some of the marks were made by utensils for eating. These indicate that food was inserted into their mouths from the right side the vast majority of the time.
The direction is often clearly from the right side, whether the person was using a tool to work with material or to feed themselves. It’s one of the clearest examples of just how long the species has preferred to use their right hands over the left.
2. A Closer Look at the Art
While teeth are incredibly reliable because it is easy to tell the direction that the tools were coming from, there is a far less painful and far more obvious example of right-hand dominance – the artwork.
There are many old pictures painted on walls and rocks, many of which have hands drawn on them. Since most of the hands on the walls are of the left hand, it means that the vast majority of the people painting on the walls were using their right hand to draw the images.
Think about the hand turkeys you used to draw in grade school. Most of you placed your left hand on the paper and traced it with your right hand. That leaves a very obvious example of just how many people in your class were right-handed.
Based on the known existing paintings, the vast majority of those who left their literal mark were right-handed.
3. A Unique Human Feature
Humans are not the only species that show a preference for one side over the other. However, there aren’t any other species that show such a strong reliance on using one side the way humans do.
One of the most obvious reasons for this is that few other animals are as reliant on tools as humans are. Even gorillas and chimpanzees don’t seem to have such a high ratio of preference when they do use tools.
Perhaps the closest example of a majority preference (though not nearly to the extent that humans demonstrate) are kangaroos. Clearly, they aren’t particularly interested in using tools, but they do demonstrate a left-handed – or left sided preference – when they are fighting.
This is actually something that is demonstrated in humans, but in a very different way.
4. The Left and Right Side of the Brain
By looking at people today, it is far easier to study hand preference and the brain. That’s because technology lets us monitor brain activity to better understand hand preference.
Though it is about 2% of a human’s weight, the brain requires roughly 20% of all the calories we consume. Yes, it really requires a lot to keep your brain functioning.
Researchers think that this amount of energy consumption is why people are more inclined to have such a strong preference for one hand over the other. By using one hand more often, it reduces the amount of duplication needed by both sides of the brain.
Researchers, medical professionals, and scientists tend to look at different parts of the brain. When it comes to handedness, it is the opposite side of the brain that controls the hand you use. If you are right-handed, then you are using the left side of your brain to control the right hand. If you are left-handed, then you are using the right side of your brain.
5. The Genetic Component
People figured out quite some time ago – after they stopped treating left-handedness as a sign of something sinister or wrong – that handedness is generally something that has a genetic component. However, it isn’t nearly as critical as we once thought. Based on one study of twins, it was calculated that handedness isn’t just based on genetics.
While it is far more likely that you will be left-handed if both of your parents are left-handed, it is still more likely you will be right-handed. If only one of your parents is left-handed, the likelihood that you will be left-handed is far smaller. If neither parent is left-handed, it is highly unlikely that you will be.
However, there are some people who are left-handed when neither of their parents are. Which side you prefer goes well beyond just genetic factors.
6. What about Environmental Factors?
The environment where a person lives seems to be a much greater indicator of their hand preference. For centuries, people were pressured to use their right hands instead of their left. People who used their left hands were considered to be doing so in error, and in the worst cases, for sinister reasons.
This isn’t something that is relegated to several centuries ago though. There are some societies today that strongly encourage – if not down-right forcing – people to use the right hand instead of the left. There are plenty of people today who would naturally use their left hand, but because of the pressure to conform they use their right hand.
7. Gender Likely Plays a Role
Males are actually more likely to be lefties than females. Based on a few studies, roughly 12% of males are left-handed compared to 10% for females. This has led some people to hypothesize that testosterone may have a role in which hand a person uses. However, it isn’t a large difference, and this requires a good bit more research.
8. The Downside to Being a Left-Handed
Being left-handed doesn’t necessarily mean that you are going to be less physically healthy compared to your right-handed counterparts. However, there are a number of ailments related to the brain that are more likely to be a problem for southpaws.
Consider that only about 10% of the population is left-handed. Now compare that to roughly a third of all people who have dyslexia are left-handed. This is a much greater percentage, which could indicate that there is a link between this disorder and a preference for the left hand.
The greater concern is that people who are left-handed also seem to be more likely to have the mental disorder schizophrenia.
Whether these problems are a result of a problem with the brain leading to a preference for one side or if environmental factors lead to the problem and a particular preference is still entirely unknown. It is thought that studying the development of the brain can help us to better understand neurological diseases, as well as leading to a better understanding of why people prefer to use one hand over the other.
9. The Benefits of Being a Left-Handed
The potential issues are high, but there are a couple of very significant benefits to being a southpaw. The most obvious is the reason why we have the term southpaw – there is a distinct advantage to being left-handed in a fight.
With such a large percentage of people using their right hand, it is very rare for boxers, baseball players, and other athletes to encounter someone who prefers to use their left hand. The repetition with other right-handed fighters means that they are accustomed to a certain method of fighting. When they encounter someone who’s a southpaw, it is far more difficult for them to adapt to punches or movements from the other side of the person standing in front of them. southpaws are accustomed to fighting people who are right-handed, so it is much easier for them to fight.
This benefit only remains if the percentage of people who use their left hand remains low. If more people were to become left-handed, people would be more accustomed to facing them.
Left-handedness is also associated with greater creativity. There are numerous studies that show that people who are left-handed tend to have better vocabularies, as well as being more creative.
10. A Difference between Fine Motor Skills and Other Motor Skills
While most people are nearly exclusively right-handed or left-handed, there is a small percentage of the population that prefer one hand for fine motor functions, but use the other hand for less complicated actions. It’s possible that you use your right hand when you are writing or using utensils. But when it comes to batting, fighting, or doing actions that are less complicated, it is more comfortable to use your left hand. This adds another wrinkle to the research because the reason for this isn’t known.
There is still so much research to be done to understand why and how, and it isn’t likely that we will figure it out any time soon. Still, it’s fascinating to watch as the different professions try to understand this phenomenon from so many different angles.