People with Slender Faces More Likely to Be Left-Handed, Susceptible to Tuberculosis
A new study from the University of Washington Health Sciences revealed that people with slender faces are more likely to be left-handed.
The study, published in the journal Laterality: Asymmetries of Body, Brain and Cognition, showed that the genes responsible for shaping facial features can increase the likelihood of left-handedness.
"In a world dominated by an obesity crisis and right-handers, ectomorphs can be different in their desires," said Philippe Hujoel, a professor at the University of Washington School of Dentistry and author of the study, in a press release. "Popular websites suggest they commonly express a desire to gain weight or muscle mass. Their slightly increased chance of being a 'leftie' is an additional feature that makes them different."
For the study, the researchers analyzed the data of 13,536 individuals who participated in three national surveys in the U.S. The researchers found that people with slender lower faces were 25 percent more likely to be left-handed.
People with slender jaws have a lower jaw that bites a bit backward, creating an overbite. Slender jaws are considered to be a common facial feature, which affects about one in five people in the U.S.
Aside from left-handedness, slender jaws have been long associated with susceptibility to tuberculosis. The findings of the present study might shed some light on some "curious geographical features."
The researchers cited that the U.K. has a high prevalence of left-handedness and slender jaws, but at the same time, it is considered to be the tuberculosis capital of Western Europe. On the other hand, Eskimos, who are known for their robust facial features and high prevalence of right-handedness, were described as tuberculosis-resistant in the 19th century.
"Slender facial features became recognized as one aspect of a slender physique of a TB-susceptible person," said Hujoel in a statement. "The low body weight of this slender physique is still today recognized by the Centers for Disease Control and Prevention as a marker for TB susceptibility."