Have you ever asked yourself: Why are some people right-handed and others do everything with their left hand? The question of why some people are left-handed while others are right-handed has long fascinated scientists.
This particularity, which affects around 10% of the world’s population prefers to use their left handis the reflection of a complex and still mysterious organization of the human brain.
Studies published in journals such as Nature Communications and Scientific Reports have provided important details, although the picture remains incomplete. What we know is that the preference for one or the other hand manifests itself in the first weeks of pregnancy, when specific genes begin to influence the development of the cerebral hemispheres in a subtle but decisive way.
What is the role of genes?
The role of genes in determining dominant hand is crucial but complex. Clyde Francks, research director at the Max Planck Institute, explains that although brain development naturally tends towards the right hand, genetic variations can influence this process. In particular, microtubules, cellular structures, likely play a role in this orientation. Specific mutations in the TUBB4B gene, which affects the formation of microtubules, were found much more frequently in left-handed peoplealthough this is rare.
Important effects on asymmetric brain development
These genetic variations represent only a small portion of the DNA, and have generally very limited effects on human characteristics. However, in some individuals, they can have significant impacts, thus influencing their handedness. These discoveries highlight the interaction between rare genetic elements and their potentially important effects on asymmetric brain development.
Does chance have a place in all of this?
In addition to genetic discoveries, Research indicates that handedness can also result from largely random processes. According to Clyde Francks, random variations in the levels of certain molecules during embryonic development could tip the scales to the left or right, regardless of genetic or environmental influences.
This hypothesis is supported by the fact that Identical twins can sometimes have different hand preferenceswhich illustrates the role of chance in brain development.
The effects of microtubules
Furthermore, microtubules could contribute to asymmetric movements within cells, thus favoring establishment of a left-right axis during embryonic development. These observations suggest that even a slight perturbation in the process can influence an individual’s hand preference, adding an element of mystery to the science of handedness.
Handedness has important implications
In addition to scientific curiosity, understanding laterality has important practical implications. Left-handed people are disproportionately represented in certain neurological and psychiatric disorders. Research shows that people with schizophrenia or autism spectrum disorders are more likely to be left-handed or ambidextrous. This association suggests links between the development of brain asymmetry and certain psychiatric characteristics, which could eventually guide new therapeutic strategies.
Still many unknowns
The mysteries of laterality continue to fascinate the scientific community and inspire future research. As studies of microtubules and other cellular structures advance, scientists hope to further decipher the complex codes that determine Why do some of us become left or right handed.
News reference:
Pourquoi naît-on gaucher ou droitier – Magazine Sciences et Avenir
