Why humans are born left-handed: scientists put forward an interesting theory

Approximately 90% of the population is right-handed, and only 10% of humanity is naturally inclined to use their left hand. Although scientists have been studying this phenomenon for a long time, answers begun to emerge only recently.

A new study published in the journal Nature Communications sheds light on why people are naturally inclined to be left-handed. Read on to learn more about the genetic basis of your dominant hand.

According to open source data, laterality is an asymmetry or incomplete identity of the left and right halves of the body, which is associated with differences in the structure and function of the two hemispheres of the brain.

Oddly enough, the hand you tend to use more is also an expression of brain asymmetry. If your left hemisphere is dominant, you are right-handed, and if your right hemisphere is dominant, you are left-handed.

Differences between the hemispheres begin to appear during fetal development. This indicates that the reason why different people have different dominant hands is genetic.

The essence of the study

Neuroscientists from the Netherlands used the human exome, a part of the genome, to investigate the difference between right-handed and left-handed people. They used materials from the UK Biobank, which included exome data from 38,043 left-handed and 313,271 right-handed people. As a result, they identified the gene TUBB4B, which is associated with changes in proteins responsible for hand dominance.

In addition, the researchers found that it is 2.7 times more likely to have rare coding variants in those who are more comfortable using their left hand. That is, TUBB4B carriers are significantly more likely to be left-handed than non-carriers.

The TUBB4B gene encodes a type of protein called tubulin that builds cylindrical microtubules. In the entire exome, it was most strongly associated with left-handedness, indicating that microtubules may be crucial in this regard.

It is not known for certain how microtubules affect individual hand dominance, but it has been suggested that they may contribute to cellular chirality in the early stages of brain development and thus influence the formation of the left-right brain axis.

However, it is worth noting that not all left-handed people have this rare coding variant. In fact, its presence increases the chances that a person will be more comfortable using the left hand, although it is not guaranteed.

Scientists recognize that the link between genes and hand dominance is still not fully understood. However, it has now become clear that the secret lies in a specific gene and its variations.

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