Why are there more right-handed people than left-handled people?

I have always been curious as to why there are more right-handed people than left-handed people. In addition, I am curious as to whether the results are caused by genetics, experience, or a combination of both. According to Live Science , approximately 90 percent of people are right-handed while only 10 percent of people are left-handed. But what is the reasoning behind this? I decided to research why there are more right-handed people than left-handed people to understand the phenomenon.

Researchers at Northwestern University have recently constructed a mathematical model that shows people are rarely left-handed due to a form of cooperation. Humans are social beings and tend to value cooperation, so they become righties as a form of conformity to a social norm. Apparently, the balance between cooperation and competition within a species is what to determine what percentage of the species is right-handed and what percentage of the species is left-handed. If humans were heavily more competitive rather than cooperative, we would see a ratio close to 50-50. This is why we often see lefties dominate certain sports, such as boxing or baseball, because they value competition over cooperation. Professor Daniel M. Abrams and graduate student Mark J. Panaggio constructed a model that concluded over 50 percent of elite baseball players are left-handed and over 10 percent of athletes in other sports are left-handed.  In terms of the causes for being right-handed or left-handed, Abrams states that genetics and environment both contribute to handedness. Even identical twins who share the same genes do not always have the same handedness.

There have also been instances where right-handedness was forced upon in certain situations, according to Scientific American. For example, some teachers would force their students to write right-handed rather than left-handed. I have also heard of ancient societies who believed being left-handed was a sign of evil which strongly encouraged people to learn to use their right hand.

There are many biological theories as to why more people are right-handed than left-handed. The Guardian provides several different viewpoints on the topic. David Colville believes that being left-handed is a recessive trait. Therefore, one in four people will have the left-handed gene, two in four people would share the trait, and one in four people would have the right-handed gene. However, human culture encourages the use of the right hand, so some left-handed people are trained to be right-handed and therefore the left-handed population is underrepresented. Another man by the name of Brian states that left-handed people had a slight starvation of oxygen on the right side of their brain in the womb. As a result, the left side of the brain became dominant at an early stage and dictated that the left hand would be the dominant one. The opposite would be true for right-handed people.

Image courtesy of http://www.handresearch.com/news/Menu_bestanden/brain-organisation.jpg

Image courtesy of http://www.handresearch.com/news/Menu_bestanden/brain-organisation.jpg

It does not seem that anyone has reached a definite conclusion on why more people are right-handed rather than left-handed. What we can conclude is that genetics and environment play a role in the determination of handedness. We could possibly do experiments where we take a sample of children from birth and attempt to train them to be a particular handedness, but there are too many unknown factors and possible confounding variables, such as genetics, that would effect the results of the experiment and not allow us to reach a definitive conclusion.

Sources Used:

http://www.livescience.com/19968-study-reveals-lefties-rare.html

http://www.theguardian.com/notesandqueries/query/0,,-4826,00.html

http://www.scientificamerican.com/article/why-are-more-people-right/

 

4 thoughts on “Why are there more right-handed people than left-handled people?

  1. Angela M Hardin

    This is one of those topic’s that I look at and go… who cares! would I want to fund it, no, but would I love to see the research done… HECK YEA. My dad is a lefty and his life got complicated doing the simplest tasks, because the tasks were set up for right handed people. good work

  2. Karly Grace Kneidinger

    I definitely agree that culture probably plays a role in determining whether you are right handed due to conformity. It’s an interesting topic that could definitely benefit from more research and scientific studies. Maybe having more people that are left-handed could lead to a change of thinking as your brain thinks and processes differently depending on what hand you use. I also wonder if the hand you use depends on the culture or country you live in. Was that considered in the studies or was it primarily focused in a single nation? I wonder if in other parts of the world there are more left handed people than right handed.

  3. John Conrad Brewster

    One of my brothers is left-handed and is the only one in my 5-person family. I think this post is funny because several times a week he would attempt to convince me that being left-handed was better in ways that don’t matter at all. For instance, one day we were swimming and he told me that left-handed people were better at seeing underwater! So I looked it up later that day and it turned out to be true! Here’s a link to more advantages of left-handers:
    http://www.anythinglefthanded.co.uk/being-lh/lh-info/advantages.html#sthash.sQOlv5L4.dpbs

  4. Rachel Wynn Evans

    This is such an interesting topic. Another thing I would consider would be the dangers associated with being left handed. Dr. Stanley Coren of the University of British Columbia stated that left-handed-people were five times as likely to die in accidents as right-handed-people were. This is not to say lefties are more clumsy, but rather they were at fault of a world designed for mostly right-handed people. Much of the infrastructure and technology was developed in favor of righties because they made up the majority, and so less thought went into functionality for the minority left-handers.
    Check out related studies here: http://www.nytimes.com/1991/04/04/us/being-left-handed-may-be-dangerous-to-life-study-says.html

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