Roughly 10% of the human population is left-handed. Now, scientists are starting to know why.
Their research also suggests that left-handedness correlates with better verbal skills. “Left-handers might have an advantage when it comes to performing verbal tasks,” said Akira Wiberg, who worked on the study. “But it must be remembered that these differences were only seen as averages over very large numbers of people, and not all left-handers will be similar.”
Researchers studied the DNA of 400,000 people, 38,332 of whom were left-handed. In isolating the genetic regions associated with left-handedness, three of those regions were linked to proteins that influence brain development — specifically, the areas of the brain associated with language.
The study also indicated a link between handedness and disease; there are slightly more schizophrenic lefties than righties, while the opposite is true for Parkinson’s disease. Researchers stressed that these connections are correlative and not causal, and that the difference in the number of people with the illnesses is small.