Our faces are a key way in which we evaluate each other. We can glean trustworthiness, threat, love and humor from a simple glance at another person's visage. Now, it appears that scientists can ascertain another fact about us simply from looking at our faces – how likely we are to be left-handed.

Trying to determine characteristics about our makeup from the look of our face isn't new. You might have heard that individuals with creases in their ears are more likely to have a heart attack, for example. In a new study published in the journal Laterality: Asymmetries of Body, Brain and Cognition, researcher Philippe Hujoel, a professor at the University of Washington School of Dentistry and an adjunct professor of epidemiology at its School of Public Health, reported that he's linked individuals with slender jaws to an increased likelihood of left-handedness.

In fact, after analyzing the data from 13,663 surveys taken by people in the United States, Hujoel came to the conclusion that those with convex faces were 25 percent more likely to be left-hand dominant than those with more rounded faces.

Individuals with these slender lower jaws also tend to have an overbite in which the top teeth extend beyond the bottom teeth. The facial profile belongs to about one in five US adolescents, according to UW.

Hujoel said that previously, those with slender jaws – often referred to as "ectomorphs" – have been linked to an increased risk of tuberculosis.

"Almost 2,000 years ago a Greek physician was first to identify slender jaws as a marker for TB susceptibility, and he turned out to be right," Hujoel said. "Twentieth-century studies confirmed his clinical observations, as slender facial features became recognized as one aspect of a slender physique of a TB-susceptible person. 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."

UW also says that the finding might help explain some historical and geographical curiosities in terms of tuberculosis. The university says that the UK has been described as the TB capital of Western Europe and has a high proportion of slender-faced lefties, while Eskimos, who have more rounded faces and are shown being more right-hand dominant in art, were known as being resistant to tuberculosis. Hujoel points out that more research is needed to find out if this is simply a coincidence or a valid hypothesis.

"In a world dominated by an obesity crisis and right-handers, ectomorphs can be different in their desires," he added. "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."

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