Slender Face Linked to Left-Handedness, Research Finds

Author: University of Washington Health Sciences/UW Medicine
Published: 2017/04/27 - Updated: 2026/01/17
Publication Type: Research, Study, Analysis
Category Topic: Medical Research - Related Publications

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This research, published in the peer-reviewed journal Laterality: Asymmetries of Body, Brain and Cognition by University of Washington professor Philippe Hujoel, analyzed data from 13,536 participants across three national U.S. surveys to establish a statistically significant correlation between facial structure and hand dominance. The findings offer valuable insights for healthcare professionals, anthropologists, and individuals interested in understanding human biological variation, particularly since slender jaw features - which affect approximately 20% of U.S. adolescents - have been historically associated with tuberculosis susceptibility, suggesting that shared genetic factors may influence both facial development and neurological lateralization. This information proves useful for those studying human evolution, genetic markers, and population health patterns, while providing a fresh perspective on the biological origins of left-handedness that affects roughly 10% of the global population - Disabled World (DW).

Introduction

Individuals with a slender lower face are about 25 percent more likely to be left-handed. This unexpected finding (abstract) 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.

Main Content

The finding was published April 26 in the journal Laterality: Asymmetries of Body, Brain and Cognition. The author, Philippe Hujoel, 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.

Slender faces are also associated with overbites and left-handedness. Image Courtesy of Philippe Hujoel.

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.

"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."

He said the finding raises the hypothesis that the genetics that shape facial features and tuberculosis susceptibility also increase the likelihood for left-handedness.

Such a hypothesis may explain curious geographical coincidences.

For example, the United Kingdom was described as the tuberculosis capital of Western Europe, and has a high prevalence of left-handedness and people with slender faces. Other populations, such as the Eskimos, were in the 19th century described as tuberculosis-resistant, having robust facial features, and typically depicted in art as showing right-hand dominance with tools and instruments.

Whether this is more than a coincidence needs further exploration, Hujoel said.

In the early 20th century, slender individuals were described as "ectomorphs" - a term that persists in popular culture as a reference to dieting and bodybuilding, Hujoel noted.

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

Insights, Analysis, and Developments

Editorial Note: What makes this discovery particularly fascinating is how it connects seemingly unrelated traits across centuries of medical observation. The fact that an ancient Greek physician noticed the connection between slender jaws and disease susceptibility - later confirmed by modern science - reminds us that careful clinical observation remains as valuable today as it was two millennia ago. While we live in an era dominated by molecular genetics and advanced imaging, sometimes the most revealing clues about our biology are literally written on our faces. For left-handed individuals who've always wondered about the origins of their handedness, this research suggests the answer might be reflected back at them in the mirror, in the contours of their jawline and the profile of their face - Disabled World (DW).