Dominant hand
Let’s get started with a very simple activity. Let’s rotate our right hand clockwise andour right leg counter-clockwise.
Next to impossible right? And that essentially evokes a fascinating question.
There exist a lot of observations through the scientific inquisition regarding the handedness of a person. Centrally, it is justified that the prime control of our hand activities lies in our brain. Our brain is organized asymmetrically into right and left hemisphere meaning that both the sides of the brain carries out different functions. The majority of human population are right handed and it perfectly makes sense because our right hand is controlled by our left brain which is associated with language and speech. While our right brain is associated with emotions, memory, reasoning and problem solving skills. Interestingly, a little number comprises the left handed population, and within that majority are males.
It is surprising that the fetus in womb has already decided its dominant hand by starting to suck the thumb of either left or right hand, indicating that the handedness is a already determined in the developmental stage. The underlying cause of this preference towards hands is estimated to be most likely determined by genes. It has been found that it is indeed a complex network interplay among several genes that determine this physical trait. Scientists have linked the developmental symmetry of the growing embryo with the handedness. The gene PCSK6, is associated with turning the embryo into distinct sides and the same is resonated to be linked to determining the right or left hand preference of the person. However, handedness may also be determined by multiple probabilistic factors like random and selective events of chance in the environment within which the embryo develops. Recently, a Genome wide association study of 400,000 UK Biobank participants, out of which 38,000 were left handed was carried out in the University of Oxford and the scientists acquired an understanding that there are four genetic loci that are linked to handedness. Three of which codes for proteins that are involved in brain development and patterning. It includes the microtubules, MAP2 and MAPT which are extensively involved in scaffolding the cytoskeleton of the cells. The cytoskeleton highly influences the left and right symmetry of cells; for example the shell of snail which might coil either to left or right. Research have found that animals also tend to have their dominant paws.
The inheritance pattern of handedness trait has been quite difficult to study as majority of left-handed children are born to right-handed parents and often left-handed parents give birth to right-handed children.
There exist several theories which culminates the concept of evolution, genetics, social pattern and psychological view about the differences between a left handed brain and a right handed brain. How about training our left hands to do some task usually done with our right hand? Are we going to change our brain that way? And what about the personality claims of right handed person versus left handed person? Well, there are people who can equally work with both hands and they are called ambidextrous and some of the most famous ambidextrous people are Leonardo da Vinci, Nikola Tesla, Sachin Tendulkar. The Alzheimer’s website suggest the training the non dominant hand with tasks like brushing teeth makes a better brain health and a stronger connections and coordination between the brain hemispheres. And, due to the association of two different hemispheres of brain with different functions it may contribute to different personality types in the psychological context. However, it turns out that doing specific task with the non dominant hand only makes you better at performing the task and shows no correlation with being a smart human being.
