For roughly 10% to 15% of the global population, the world is set up just a tad differently. Lefties, those who favor their left hand for tasks, have long been a subject of curiosity. Now, a groundbreaking study sheds light on the genetic underpinnings of left-handedness, revealing fascinating connections to brain structure and potentially, enhanced verbal abilities.
Prior research using twins hinted at a genetic influence on handedness, but this new study, conducted by Oxford University researchers and published in the journal Brain, takes a giant leap forward. It identifies specific genetic variants that differentiate left-handed individuals from their right-handed counterparts.
The findings hold the potential for a fascinating correlation: left-handedness and superior verbal skills. Dr. Akira Wiberg, a researcher on the study, highlights this intriguing possibility. “Our study raises the exciting prospect that left-handers might have an edge in verbal tasks,” he acknowledges in a press release. But Dr. Wiberg also emphasizes caution, noting that “these differences were observed as averages in large groups, and individual left-handers will vary.”
Further investigation is needed to solidify this potential advantage. Dr. Gwenaëlle Douaud, co-author of the study, underscores this point. “We need to assess if this heightened coordination between language areas in the left and right hemispheres of left-handed brains translates to a concrete verbal ability advantage. This requires a study with in-depth verbal testing,” she explains.
The research, funded by the UK’s Medical Research Council and Wellcome, a medical research charity, involved a massive dataset. The scientists analyzed the DNA of 400,000 individuals, including over 38,000 left-handers, from the UK Biobank, a treasure trove of health information from volunteers across the country.
Their analysis identified four genetic regions linked to left-handedness. Interestingly, three of these regions were associated with proteins that influence brain development and structure. Specifically, these proteins impacted microtubules, a crucial component of the cell’s internal scaffolding, known as the cytoskeleton.
The cytoskeleton dictates a cell’s form and function within the body. Previous research has shown its role in establishing “left-right asymmetry” in various animal species. “Many creatures exhibit left-right asymmetry during development,” explains Dr. Douaud, citing snail shells that coil in either a left or right direction.
The researchers then analyzed brain scans from roughly 10,000 participants. They discovered that the genetic variations linked to left-handedness corresponded with differences in the brain’s white matter tracts. These tracts, in particular, connect the regions of the brain responsible for language processing.
Furthermore, Dr. Douaud reveals that the study suggests “more coordinated communication between the left and right hemispheres of the brain in left-handed individuals.” She elaborates, explaining that left-handed people exhibit “a higher level of synchronization in their brain’s natural oscillations, even at rest.” This synchronization, she adds, occurs “specifically in brain areas dedicated to language.”
The study also hints at a potential link between the aspects of brain development associated with handedness and the risk of developing schizophrenia or Parkinson’s disease. Dr. Dominic Furniss, another co-author of the study, elaborates on this connection. “It’s been known for some time that there’s a slightly higher prevalence of left-handedness among people with schizophrenia compared to the general population,” he explains to CNN. “Conversely, there seems to be a slightly lower prevalence of left-handedness in those with Parkinson’s disease.“
Dr. Furniss suggests that the new research “indicates that these conditions, along with handedness, might be products of fundamental differences in brain development, partly driven by genes.” However, the researchers emphasize that the observed association between handedness and these diseases suggests correlation, not causation. Additionally, the differences in prevalence are very subtle.
This groundbreaking study opens exciting avenues for further research, potentially revealing connections between handedness, verbal abilities, and even neurological conditions. As scientists delve deeper, our understanding of this fascinating human trait continues to evolve.