Earliest members of genus Homo may have ditched hard foods on the road to becoming human
Title:
Earliest members of genus Homo may have ditched hard foods on the road to becoming human
Subtitle:
New study finds Homo habilis was biomechanically limited in producing high bite forces— forcing scientists to re-think the timing of dietary shifts in human evolution
Body:
New work by an international team of researchers suggests that the earliest member of the genus Homo, a species known as Homo habilis (“handy man”), was limited in its ability to bite forcefully into hard foods—offering new insights into the dietary and evolutionary shifts that helped shape the human lineage.
The study, published this week in Royal Society Open Science, uses advanced computer simulations to analyze bite force mechanics in Homo habilis. 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.
“Our results point to a fundamental change in feeding behavior with the appearance of Homo habilis,” said Dr. Justin Ledogar, assistant professor in ETSU’s Department of Biomedical Health Sciences and the study’s lead author. “The ability to process exceedingly hard or tough foods with high bite forces was reduced in Homo habilis compared with earlier hominin species.”
The research team created a biomechanical model of the Homo habilis skull and subjected it to simulated biting scenarios using finite element analysis—a digital modeling method commonly used in engineering. The model was compared with those of earlier human ancestors, recent modern humans, and modern chimpanzees. The team found that, unlike earlier hominins, Homo habilis was at an elevated risk of jaw joint injury during strong molar bites that limited the amount of bite force that could be generated at the back teeth. Modern humans face the same challenge, which may help explain the prevalence of jaw joint pain today.
The new study challenges the predominant view that a reduced ability to process mechanically challenging
foods first evolved in Homo erectus, a later human ancestor. “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 study’s implications extend beyond just biting mechanics. Relaxed selection on traits related to high bite force production may have opened the door to changes elsewhere in the skull—perhaps influencing speech, facial expression, or even brain expansion.
The study, titled “Bite force production and the origin of Homo,” is available online at https://doi.org/10.1098/rsos.241879.
Contact:
Dr. Justin A. Ledogar
Department of Biomedical Health Sciences
East Tennessee State University