Individuals with a slender lower face are about 25 percent more likely to be left-handed. This unexpected finding was identified in 13,536 individuals who participated in three national surveys conducted in the United States. This association may shed new light on the origins of left-handedness, as slender jaws have also been associated with susceptibility to tuberculosis, a disease that has shaped human evolution and which today affects 2 billion people. The finding was published on April 26, 2017 in the journal Laterality: Asymmetries of Body, Brain and Cognition. The article is titled “Handedness and Lower Face Variability: Findings in Three National Surveys.” The author, Philippe Hujoel, PhD, is a professor at the University of Washington School of Dentistry and an Adjunct Professor of Epidemiology at its School of Public Health. Slender jaws are a common facial feature, affecting about one in five U.S. adolescents. Past U.S. surveys measured the prevalence of this condition by evaluating how the upper and lower teeth come together. People with slender jaws typically have a lower jaw which bites a bit backward, giving them a convex facial profile and what's commonly called an overbite.
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