Left or Right Handed?

When will you know your baby's handedness and why?

It is widely known that the pattern of human handedness favours the right. In fact, 90% of the adult population is right handed. What is less clear is how handedness emerges and at what age a child shows a definite preference for either hand. Newborns are born with equal ability in their left and right sides, but over the next few years show the adult pattern for handedness. Even though adults can train their weaker side, they can never switch the preference for a certain hand!

Why are we left or right handed?

There have been research studies carried out to try to explain how handedness as evolved and it can be concluded that it is through genetic causes and evolutionary natural selection.

It is argued that as the left hemisphere of the brain for the majority of people controls our language and speech functions. The left side also controls the movement in the right side of our bodies. Over the millennia, these two factors have resulted in the majority of humans becoming right handed. Early in our human development we moved from hand gestures for communication to verbal and then written forms of communication, leading us to be, therefore, right hand dominant.

The majority of the people in the world are right handed, with only about 10-15% being left handed and 1% having no preference and as a parent it is interesting to know when your baby will demonstrate a preference.

When will I know if my baby is left or right handed?

A new born baby doesn’t show any hand preferences. Their jerky, reflexive movements should be equal on both sides of their bodies. However, even at an early stage your baby may have a preference for turning their head in one direction. A greater percentage of infants - 60 to 70 % - turn their heads to the right more of the time. Research has even been carried out in utero, where one study found that 90% of babies sucked on their right thumbs.

From about four to six months your baby will start to hold objects more securely in their hands and the majority will prefer to hold the rattle in their right hand. However, for many months to come this isn’t exclusive and they will often pick up objects with their other hand. As their motor skills become more refined, they will continue to use both hands to perform more complex tasks with toys or objects. Which hand they use can often depend on simply which hand is closest to the object of their desire!

By the time they are 3 or 4, once their language skills have developed, most children will show a clear preference for one hand. This becomes more obvious when they undertake difficult fine motor tasks such as holding a pen to write or a crayon for colouring.

Are there advantages to being left handed?

Studies are continuing to be carried out to assess if there advantages to being left handed.  

One such researcher Chris McManus from UCL asserts that evolution is moving towards left-handers as their numbers are increasing and that proportionally more left-handers are considered to be high achievers. He states that the way a left hander’s brain is structured has led to them being able “to process language, spatial relations and emotions in more diverse and potentially creative ways. Also, a slightly larger number of left-handers than right-handers are especially gifted in music and math. A study of musicians in professional orchestras found a significantly greater proportion of talented left-handers, even among those who played instruments that seem designed for right-handers, such as violins. Similarly, studies of adolescents who took tests to assess mathematical giftedness found many more left-handers in the population” Scientific American 

There are, of course, other studies which suggest that the proportion of high achievers has been overstated and that the number of left handers who underperform or at “the low end of cognitive spectrum” is higher than right handers.

Interesting fact: 4 out of the last 6 Presidents of America have been left handed!


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