Left-handedness is influenced by multiple factors, including genetics and brain development. Studies reveal distinct characteristics in brain organization and function among left-handed individuals.
Distinct coordination between brain hemispheres
A 2019 study by Oxford University analyzed genetic data from nearly 400,000 individuals in the UK Biobank. Within the group that underwent brain imaging, there were 721 left-handed and 6,685 right-handed individuals. Results showed stronger functional connectivity between language networks in both brain hemispheres among the left-handed group.
For most individuals, language functions primarily reside in the left hemisphere. However, the degree of specialization between the two hemispheres varies among individuals. In left-handed people, language processing may be less lateralized compared to right-handed people, though not everyone shares the same brain organization pattern.
Stronger functional connectivity indicates that brain regions have more closely linked activity, but it does not mean they process information faster or more efficiently in all situations. The authors also noted that further research is needed to determine if this characteristic offers any linguistic advantages.
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Left-handed individuals may exhibit differences in functional connectivity between language regions in both brain hemispheres. Illustration: Bao Bao |
Handedness influenced by multiple genes
Handedness is not determined by a single gene. Multiple genetic variants, along with developmental factors, can contribute to the tendency to use either the left or right hand.
A study published in 2024 in the journal Nature Communications analyzed gene sequencing data from approximately 38,040 left-handed and 313,270 right-handed individuals in the UK Biobank. Scientists discovered that rare variants affecting the protein structure of the TUBB4B gene are linked to left-handedness. The prevalence of these rare variants was 2,7 times higher in the left-handed group compared to the right-handed group.
The TUBB4B gene is involved in producing beta-tubulin, a component of microtubules within cells. Microtubules contribute to maintaining cell structure, intracellular transport, and the development of neurons. This finding provides further evidence for the role of brain development mechanisms in shaping handedness.
Handedness not a determinant of intelligence
Differences in brain connectivity lead many to believe that left-handed individuals possess superior language, cognitive, or creative abilities. However, current scientific evidence is insufficient to confirm this.
According to Healthline, studies on the relationship between handedness and IQ scores show inconsistent results. Some analyses note that right-handed individuals have slightly higher average IQ scores, while other studies found no significant differences. Overall, the average disparity between the two groups is very small and not practically significant.
Intelligence is a broad concept, encompassing various abilities such as reasoning, problem-solving, learning, and adaptation. One characteristic of brain organization cannot represent all these abilities.
Similarly, although left-handed individuals appear more frequently in some sports, that advantage may be related to opponents being less accustomed to competing against left-handers, rather than reflecting superior cognitive ability.
Bao Bao (Compiled)
