Dietary shifts shaped the earliest members of the human genus
As human skulls evolved away from high bite force production, it could have opened
the door to
changes elsewhere – potentially influencing speech, facial expression or brain expansion.
Led by East Tennessee State University’s Dr. Justin Ledogar, an international team of researchers published a new study in April that suggests the earliest human ancestors may have ditched hard foods earlier than previously believed.
By utilizing advanced computer simulations, researchers were able to compare bite force mechanics of earlier human ancestors, recent modern humans, modern chimpanzees and Homo habilis – the earliest member of the genus Homo – by creating biomechanical models of their skulls.
Results show that Homo habilis was structurally constrained in its ability to crunch into hard foods with its molars — a limitation that persists in modern humans and offers fresh insight into the dietary adaptions and evolutionary developments that helped shape the human lineage.
The findings were published in the April 2025 edition of Royal Society Open Science.
“Our results point to a fundamental change in feeding behavior with the appearance of Homo habilis,” said Dr. Justin Ledogar, an assistant professor in ETSU’s Department of Biomedical Health Sciences in the College of Public Health. “The ability to process exceedingly hard or tough foods with high bite forces was reduced in Homo habilis compared with earlier hominin species.”
A three-dimensional model of a Homo habilis skull used to simulate its bite force mechanics.
The study challenges the predominant view that a reduced ability to chew hard foods first evolved in Homo erectus, a later human ancestor. Modern humans face the same challenge as our earlier ancestors, which may help explain the prevalence of jaw joint pain today.
“Homo habilis probably couldn’t crack nuts or chew hard roots and tubers the way its predecessors could,” said Ledogar. “And that’s a kind of big deal—it suggests a major dietary shift was already underway at the dawn of our genus.”
The implications of the study extend beyond just diet.
As human skulls evolved away from high bite force production, it could have opened the door to changes elsewhere – potentially influencing speech, facial expression or brain expansion.
The study, titled “Bite force production and the origin of Homo,” is available online at https://bit.ly/4482jZA. To learn more about the ETSU College of Public Health, visit www.etsu.edu/cph/.
From innovative scholarship on vitamin deficiencies to the discovery of a giant flying squirrel, Ledogar is one of the dozens of ETSU faculty generating cutting-edge scholarship.
East Tennessee State University was founded in 1911 with a singular mission: to improve the quality of life for people in the region and beyond. Through its world-class health sciences programs and interprofessional approach to health care education, ETSU is a highly respected leader in rural health research and practices. The university also boasts nationally ranked programs in the arts, technology, computing, and media studies. ETSU serves approximately 14,000 students each year and is ranked among the top 10 percent of colleges in the nation for students graduating with the least amount of debt.
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