Righties and Lefties

Right-handed people dominated the world since the Stone age. We do know that because researchers figured it out by the size of the arm bones (The humerus) found in ancient skeletons. They examined also the wear patterns of the pre-historic tools. Lefties are believed to make around 10% of the population in the Western countries. Others can be true ambidextrous with equal skills which is very uncommon or mix-handed and favor different hands for different tasks.

Many scientists believe that handedness is partly shaped by the genes but it is only in 2019 that different parts of DNA were identified for left and right handers. The brain of 9,000 British subjects were analyzed through brain scans and in lefties, it was found that parts of the right and the left sides of the brain can process language works in better tandem.  Others report that left handlers are more fluent speakers but it remains questionable.

Fetuses were studied in the womb and it was discovered that around 9-10 weeks of life, they were able to move their arms. During the second trimester, clear preference for sucking one thumb over the other was noted. Until a child reaches the age of 2 or 3, a parent will not get a good sense of the dominant extremity but many children will continue to switch hand in early childhood.

Studies have shown that non-right-handed students are more likely to struggle in school and have ADHD symptoms especially if they become ambidextrous. Other studies have shown that the more a child switch hands back and forth, the more likely they may become dyslexic. Nobody knows why they have that tendency but some believe that having inconsistent dominant hand may be a bigger problem than a child with left-handedness.

The right side of the brain controls the muscles of the left of the body and largely drive musical and spatial abilities. This may explain why left-handers have creative professions. Mirror writing where letters are reversed or written backwards almost always done with the left hand. Left-handed children score higher on verbal reasoning. They may more easily participate in gifted programs.

An interesting fact is seen with right-handed seniors when researchers found that these subjects relied less and less on their dominant extremity, the older they become. So, as their right handers grew slower and unsteady, they can handle any task as well with the left hand. They do remain righty. In sports, lefty appears to have an edge especially in boxing or fencing where they seem to bring an element of surprise to their opponents especially when they are facing a righty. In baseball by example, the left hitter has a tendency in standing closer to the first base.

There is a well-established link between left-handedness and mental conditions like Schizophrenia, which is known to cause hallucinations and impaired thinking. Some other studies have also showed a strong relation between mood swings, restlessness and neuroticism (anxiety and fear of catching a mental disorder). Animals like Apes (wild Champ or in captivity chimpanzees) have also demonstrated handedness using their left hand as often they are fishing for thermites. This task is requiring sheer force instead of motor skills to extract the insects. The wild champs were more likely to favor their right hands.

Biases has existed against left-handlers throughout history. In the Middle-Ages, the devil was believed to be a lefty. In Japan and China and other Asian countries, there are fewer left handlers than we have on the West. American teachers believed for a while that left-handlers were more prone to developmental disorders and students were pressured to use their right hand. This was seen in almost all the religious schools. Many recent presidents like Ronald Reagan, Georges H.W. Bush, Bill Clinton. Barack Obama, were all left-handlers as well as Bill Gates, Tom Cruise, Oprah Winfrey, Prince Charles and his son Prince William 

Are you left or right brain dominant? Are left brained people smarter? It is said that left-brained people are said to be more likely cynical and cold in their judgements and problem-solving while right-brained people are often characterized as artistic, innovative and random. Actually, nobody seems to be truly right or left-brained, but seems to have activities in both sides.

As a surgeon, I worked with left handers assistants and I found many to be “ambidextrous” because it is sometimes awkward to see them using their left hand to cut with right handle scissors or to hold on a retractor. Times have changed because, nowadays many products especially in the kitchen are made for lefties or righties. You can even find knifes where the sharpened edges are on the right side of the blade for cleaner slicing. The left-brain dominant people tended to be logical and rational but often organized while the right-brain people demonstrate their creativity, imagination and artistry.

Our brain appears to be divided in two inequal spheres. The neocortex is the most advanced part of the brain. It determines how to think and decides whenever we become right or left handlers. It also determines how we think. Dominance is dictated by the entire neo-cortex. The left-brain dominant people happen to be clinical and cold in their judgments and problems solving. Language recognition is attributed to the left hemisphere and this may be the reason why languages are easily learned among the left-brain dominant. Having the ability to use at ease the right or the left hand is a blessing for an ambidextrous. Their hand writing will look similar and beautiful no matter what hand is being used.

Experts believe that the left brain is wired to the right brain and this way exercises a control on it. Strangely, a left-hand person is likely to be a dog-lover and prefer classical music. They can’t be hypnotized. Many lawyers and bankers or judges happen to be left brained. For others, the right hemisphere is associated with a lot of creativity and emotion. They look like they may have more intuition. Inversely, the right side of the brain controls the left side of the body and a right brain person is often left-handed. More, they show some artistic and innovative aptitude. Their thought processes may be seen at time as irregular but often demonstrates a lot of originality. Others may be inventive. Politicians, actors and athletes tend to be right brained and bring spontaneity and creativeness in their activities.

We have already discussed the way in schools, the left-brained ways of thinking is generally favored because of the logical and analytical skills they exhibit over the right-brained person. The right brained concentrate on the visual and artistic, they are good in athletics and acting. They generally have good memory but can be hypnotized.

Around 12% of people are left-handed and researchers have pointed out that there is sometimes no way to know which hand is dominant. Does it represent a strong genetic influence…? 1% of people are ambidextrous. An ambidextrous is rarely found. Although, I have learned how to play some sports with both hands, like ping-pong, baseball and I shoot with both feet playing soccer. In playing hockey, I can use the stick with either upper extremity and in baseball, I hit on either side as a right or a left hitter but it does not place me in the category of an ambidextrous.

An Ambidextrous is in a league of his own and its ambidexterity is classified like a cross-dominance. If the left-handed person is right-brain dominant and a right-handed person left-brain dominant because one side of the brain controls the workings of the other side of the body and your brain will control the way you handle a pen. Actually, new researches point out that it may not be as simple. It seems that there is more symmetry between both sides of the brain in a lefty. In a righty, tasks are equally divided in each hemisphere like language acquisition is located in the left hemisphere while for lefties it can change to a point that the language acquisition can be found in both sides of the brain. This symmetry is also seen for ambidextrous.

You can be ambidextrous but still have one hand more dominant than the other one. Some may have used the non-dominant hand because of injury or pressure. An ambidextrous is very unique. In sports activities, it gives you a tremendous advantage to be able to use either hand. In baseball, being a switch hitter or a switch pitcher can allow you to use the weakness of the opponent. Tennis, soccer players or other athletes can perform better in using the element of surprise. The same can be seen with musicians. We have seen the way Ringo Star, the famous left-handed Beatle drummer play  with a right-handed drum kit.

More, ambidextrous can experience “Synesthesia” when the senses appear to be coupled in a way which number, letter or music is seen as colors. This phenomenon may be seen when two adjacent areas of the brain are activated at the same time, creating a “cross-activation”. Researchers seems to agree that such synesthesia is definitely a “hallmark” of the ambidextrous. This conception of symmetrical brain seems to create the cross-activation. It looks as well that the one who become ambidextrous may have started as a dominant left handler.

In a South African book “On the Other Hand” written by Howard Kushner, it was reported that a punishment to left handlers was to place their left hand on boiling water so they will not be tempted to use it. The left hand was also associated to witchcraft during the biblical times and the term “Sinistra” was used for Left. It may be why the left hander were associated to sinister or from the devil. Many lefties were forced to use their right hand and out of necessity, they become right hander.

Are we really right or left brainer…? A lot of what we consider like activity of the right brains also done by the left brain. In fact, more people demonstrate equal activities on both sides of the brain. We may see a creative person as a right brainer or an analytic mathematician like a left-brainer but the brain activity come from both sides. Calling one a left or a right brained is not that important because both hemispheres are functioning and nobody is entirely one or the other. There is always a mix function with a little preference for one side of the brain or the other. This certainly can explain why I may be artistic with a right-brain function but more apt at learning a foreign language with a left-brain function.

Genetic may have more to explain when we know that 90% of people are right-handed (left side functioning…?) and the remaining 10% are left-handed (right side functioning…?). In the society, we are perhaps visualizing people on the way they are doing things and using their right or left hands: the left handlers (right brained) are creative and intuitive, they are thinker. On the counter part, the right handlers (Left brained) pay more attention to the logical aspect of things.  The notion of right or left brain may be widespread and accepted in the community, but it is a misconception.

It is true that some brain function resides on different sides of the brain, or more on one side perhaps than the other one… especially when one suffers from a stroke… The control of the language is certainly on the left side of the brain while areas in the right brain control movement of the left arm and leg. The front part of the brain (Frontal Lobe) is linked to difficulty in planning with impaired creativity and loss of motivation. The frontal lobe is the lobe of the personality while the back of the brain (Occipital Cortex) is responsible of the visual information and can produce cecity. In anyway, a CT scan or a MRI scan or not even an autopsy on the brain of an artist compared to the brain of a lawyer can reveal a difference.

AT the University of Utah in 2013, studies have shown that the concept of right or left brain to be certainly a myth because activities were found similar on the right or the left side regardless the personality of the individual. It seems inaccurate to be able to stipulate that because one person is artistic, these traits are related to one particular side. An individual personality can’t be determined by the dominance of one side of the brain. We will have to wait a discover if Genetic has a role to play in the fact that we are right or left brainer?

Maxime Coles MD
Boca Raton Fl
Feb 2022



1-    Ade Kovel, C, Carrion-Castillo, A and Franks C (2019). A large-scale population study of early life factor influencing left handedness. Scientific Reports; 9(1). https://doi.org/10.1038/s41598-018-37423-8

2-    Hubbard, E. M (2007). Neurophysiology of synesthesia. Current Psychiatry Reports, 9(3), 193-199. https://dol.org/10.1007/s11920-007-0018-6

3-    Paracchini, S (2020). Human Handiness: A meta-analysis. Psychological Bulletin, 146(6), 482-524.https//doi.org/10.1037/bul000229

4-    Papadatou-Pastou, M.; Ntalka, E.; Schmitz, J.; Manufo, M. R.; Ocklenburg, S.; and al (2010) Mixed-handedness is linked to mental health problems in children and adolescents. Pediatrics, 125(2). https://doi.org/10/1542/peds.2009-1165.

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