We are (Mostly) All Right

Human Asymmetry Does Not Stop at Handedness.

Posted Dec 15, 2018

I’m all right.  You’re all right. I favor my right hand and so does most of the world’s population. But asymmetry does not stop there.  Data below, gathered from a high school class of nineteen students (Barkman, Coaching Science Stars-Peptalk and Playbook, 1991), show an inclination.  What patterns do you see?

Courtesy of Robert Barkman
Handedness of 19 High School Students
Source: Courtesy of Robert Barkman

Most students are right handed. If they are right handed, they also favor their right leg, right eye, right ear, and their right side of the face.1

The side (hemisphere) of the brain favored is opposite to their favorite hand. Did you see these patterns?

Patterns of laterality raise some interesting questions. Why are 90% of us right handed and left brained? What could account for this connection between brain and hand?  Is it an accident of nature? A coincidence? Or, is there something to discover from this hand and brain pattern? No one knows for sure, but the results of recent research may help to answer this question (Papadatou-Pastou, 2011).

We all communicate with our hands. To Italians, gesturing comes naturally. They talk with their hands as much as their mouths. Isabella Poggi, a professor of psychology at Roma Tre University and an expert on gestures, has identified around 250 gestures that Italians use in everyday conversation. Some contend that hand gestures may have been the earliest form of language (Donadio, 2013). 

Most of us are hard-wired to support this type of communication.  That’s because the centers for right-handedness and communication (speech and language) are near neighbors on the left side of the brain (McManus, 1999). The handedness and communication centers talk back and forth to each other to ensure that the mouth, hand, and brain are on the same page (Bernardis and M. Gentilucci, 2006).  Hands gestures can reinforce what the mouth is saying, even when two people speak different languages.  If you have ever traveled in a country where English is not the native language, you likely survived the experience by relying heavily on hand gestures. Some believe that during human evolution, the skill to exercise the fine motor movements of the hands evolved before we could speak.  If true, it is likely that our human ancestors talked with their hands before they uttered their first few words (Papadatou-Pastou, 2011).

In every population of the world studied so far, researchers always find a minority of left-handed people. In the United States, these outliers make up 10-13 % of the population. In countries such as China, however, that number is smaller because of the social pressure placed on people to be right- handed (Carter-Saltzman, 1980). Children, for example, are expected to hold and use chopsticks with their right hand.  If a child mistakenly used his left hand, his father might rap his hand with a chopstick. Chinese schoolchildren are also threatened with slap of a ruler across the knuckles if they pick up a pen to write with their left hand (Wun, 1989).

It seems that lefties have been in the minority for quite a while (McManus, 1999). Studies dating back thousands of years- to the time of the Neanderthals- show clues indicating that even a minority of our Neanderthal ancestors were left handed.  Because bones of the preferred arm are more robust, researchers can determine from a skeleton which hand is favored. University of Kansas researchers report that 89 percent of European Neanderthal fossils (16 of 18) showed clear preference for their right hands. This is very similar to the prevalence of right- and left-handers in modern day human populations (University of Kansas, 2012).

Because the frequency of left-handedness has seemingly remained stable over time, it suggests that there has been pressure by natural selection to preserve left-handedness in the population (Perri Klass, 2011).    But what advantage could underlie this pattern?

 Courtesy of Parent 24
Works of Art Created by Left Handers
Source: Courtesy of Parent 24

Perhaps, it is because lefties seem to have the advantage over right-handed people in certain areas. Lefties are over-represented among architects, musicians, and artists. Creativity may be a feature of left-handers. Benjamin Franklin and Leonardo Da Vinci created their inventions left-handed. Picasso and Michelangelo created their works of art left-handed. Researchers aren’t sure why, but those who are left handed seem to make up a disproportionately large part of those who are highly intelligent with I.Qs more than 131.  Twenty percent of all Mensa members are left-handed. When you consider that less than 10 percent of the total population is left-handed, this makes for many smart lefties (Anything Left Handed, n.d.).

A study published in the journal Neuropsychology suggests that left-handed people are faster at processing multiple stimuli than righties (Cherbuin & Brinkman, 2006).  It could mean that left-handers have a slight advantage in sports, gaming and other activities such as the complex task of piloting a fighter jet in which large volumes of stimuli are thrown at someone simultaneously or in quick succession. This helps to explain why lefties excel in tennis, fencing, and boxing and other sports (Panaggio, 2012) (SciGuru: Science News, 2012). These and other studies reveal that by looking at someone’s hands, we can learn something about the inner workings of their minds.

Courtesy of JF Ptak Science
Prevention and Correction of Left Handedness
Source: Courtesy of JF Ptak Science

And, it makes one wonder about all those teachers who made their left-handed students struggle to use their right hands. They may be rethinking this right about now.    

1 The favorite side of face shows more emotion than the opposite side signaled by the appearance of lips, dimples, and wrinkles.

(Special thanks to Jane Johnson Vottero who helped edit this article and is a member of the super talented left-handers.)

References

Barkman, R. (1991). Coaching Science Stars-Peptalk and Playbook. Tucson, AZ: Zephyr Press.

Papadatou-Pastou, M. (2011). Handedness and language lateralization:Why are we right handed and left-Brained? . Hellenic Journal of Psychology, 248-265.

Donadio, R. (2013, June 30). When Italians Chat, Hands and Fingers Do the Talking. Retrieved from New York Times Europe: http://www.nytimes.com/2013/07/01/world/europe/when-italians-chat-hands-and-fingers-do-the-talking.html

 McManus, I. (1999). Handedness, cerebral lateralization and the evolution of language. In M. C. Lea, The descent of mind: Psychological perspectives on hominid evolution (pp. 194-217). Oxford University Press.

Bernardis P and M Gentilucci , Speech and gesture share the same communication system.      Neuropsychologia. 2006;44(2):178-90.

Carter-Saltzman, L. (1980). Biological and sociocultural effects on handedness; Between biological and adoptive families. Science , 1263-65.

Wun, D. (1989, June 12). The influence of culture on handedness. (R. Barkman, Interviewer)

University of Kansas. (2012, August 23). Research verifies a Neanderthal's right-handedness, hinting at language capacity. Retrieved from University of Kansas: http://archive.news.ku.edu/2012/august/23/neandertal.shtml

Perri Klass, M. (2011, March 6). On the Left Hand, There Are No Easy Answers. Retrieved from New York Times ; View: http://www.nytimes.com/2011/03/08/health/views/08klass.html?_r=1

Anything Left Handed. (n.d.). Advantages of being left-handed. Retrieved from Anything Left Handed: http://www.anythinglefthanded.co.uk/lh-info/advantages.html#sthash.jGuFHcY0.kdKAVIvO.dpbs

Cherbuin, N., & Brinkman, C. (2006). Hemispheric interactions are different in left-handed individuals. . Neuropsychology, 700-707.

Panaggio, D. M. (2012). A model balancing cooperation and competition can explain our right-handed world. Journal of the Royal Society Soc. Interface, http://rsif.royalsocietypublishing.org/content/early/2012/04/24/rsif.2012.0211.full.

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