It’s natural for people to think about the implications of being right-handed or left-handed. When considering handedness (1), there are four distinctions: people are either left-handed, right-handed, mixed-handed, or ambidextrous (2). Among these differences, right-handedness is more common among individuals. Researchers have approximated that only 15% of the human population is left-handed (3). When thinking about this low percentage, the question arises of why there are more right-handed individuals. Coupled with this are challenges to commonly held views. Are left-handed people smarter? And do some individuals use a particular side of their brain more? If so, does that affect their interests or skills? Scientists have not been able to clear up all of the questions out there. However, copious amounts of research and data explains the science associated with handedness.
One way that scientists explain handedness is with genetics. Like most traits we have, such as hair color, eye color, and height, handedness can correlate with genes that we receive from our parents. Researchers have found that children with two left-handed parents have a greater chance of being left-handed than those born of two right-handed parents. Still, there is a greater chance that any child will be right-handed. Every individual has a unique lineage, which also influences their chances of being left or right-handed. There are over 40 genes that play a role in determining hand preference, but scientists do not know the exact reason that the combinations resulting in right-hand preference are more common (4).
Some scientists and individuals believe that right-handedness is common because the left hemisphere of the brain, which is in control of language and speech capabilities, controls the right side of the body. The right hemisphere controls movements of the left side of the body and the left hemisphere controls movements of the right side of the body. This is called contralateral control. The left hemisphere of the brain is usually associated with controlling language skills– it would make sense that the majority of people use their right-hand to write. To explain why there are left-handed people, the French physician and anthropologist Pierre Broca conducted research. His hypothesis included the idea that left-handed individuals must use the right hemisphere of their brains for language skills. This theory was based on the contralateral control between the body and the brain. However, in studies researchers found that 80% of left-handed individuals still relied on the left hemisphere of their brain for language skills(5). The fact that there are left-handed people who rely on the right-hemisphere of their brain for language skills challenges cerebral dominance, which is the idea that a particular hemisphere of the brain predominantly controls a set of tasks (6). However, this irregularity is rare and mainly supports contralateral control.
According to the idea of cerebral dominance, handedness would be a way of identifying what part of the brain an individual uses more. Since the majority of people are right-handed, that would mean that their left-hemisphere is controlling the majority of their actions. Since the left-hemisphere is responsible for things such as analytical skills and logic, there are questions and myths that revolve around ideas such as right-handed people being less creative but more analytical than left-handed people. When approaching such questions, it is important to note that people may have a dominant hemisphere that controls the majority of their actions, but both of their hemispheres work together to complete a variety of tasks. No one uses one particular side of their brain more than another. Researchers have concluded that the quizzes and myths of being left-brained or right-brained are wrong (7). Although the left hemisphere may be in control of the majority of actions of right-handed individuals, these individuals are not given an advantage of tapping into the functions of the right or left hemisphere more.
Even after considering all of these statistics and studies, you can look into more when researching handedness. Much of the information available explains what is common, but there are still irregularities such as the 20% of left-handed people that rely on the right-side of their brain for language skills and the people that are naturally ambidextrous. There is a mixture of solid evidence that breaks down myths and theories that explain the small irregularities. However, there is room for more studies to explain the ins and outs of handedness.
I would encourage you to look beyond this article to explore the other theories behind the prevalence of right-handedness. They might be based on cultural beliefs, evolutionary theories, or something else.
Feel free to comment below to share what you find and ask questions about what still confuses you. Here are some links that might clarify some possible confusion and explain further about handedness.
References and Footnotes
- Handedness is the tendency to use a certain hand more naturally than the other.
- Ambidextrous people can use either their left-hand or right-hand equally to perform activities. People who are mixed-handed may be able to use both hands, but they are usually more comfortable with either their left-hand or right-hand depending on the task.
- Chow, Denise. “Why Are Some People Ambidextrous?” LiveScience, Purch, 2 Apr. 2010, www.livescience.com/32523-why-are-some-people-ambidextrous.html.
- U.S Department of Health & Human Services. “Is Handedness Determined by Genetics? – Genetics Home Reference.” U.S. National Library of Medicine, National Institutes of Health, 19 June 2018, ghr.nlm.nih.gov/primer/traits/handedness
- Minderovic, Zoran. “Handedness.” The Gale Encyclopedia of Psychology, edited by Bonnie Strickland, 2nd ed., Gale, 2001, pp. 293-294. Gale Virtual Reference Library, http://link.galegroup.com/apps/doc/CX3406000300/GVRL?u=caro78187&sid=GVRL&xid=b8907d89. Accessed 23 June 2018.
- Galeotti, Sandra, and Brian Douglas Hoyle. “Cerebral Dominance.” The Gale Encyclopedia of Neurological Disorders, edited by Stacey L. Chamberlin and Brigham Narins, vol. 1, Gale, 2005, pp. 215-216. Gale Virtual Reference Library, http://link.galegroup.com/apps/doc/CX3435200088/GVRL?u=caro78187&sid=GVRL&xid=e8618454. Accessed 23 June 2018.
- Wanjek, Christopher. “Left Brain vs. Right: It’s a Myth, Research Finds.” LiveScience, Purch, 3 Sept. 2013, www.livescience.com/39373-left-brain-right-brain-myth.html.