If you’ve ever suffered from a sore jaw that burst or clicked when you chew gum or bite hard food, you may be able to blame it on your deceased ancestors.
This is according to a study conducted by Duke University on the chewing mechanics of an ancient human relative called Homo floresiensis, which inhabited the Indonesian island of Flores before our species arrived there around 50,000 years ago. .
Not much over three feet tall, the hominin’s small stature has earned it the nickname “Hobbit,” after characters in JRR Tolkien’s “The Lord of the Rings”. For the new study, which was published on August 13 in the journal Interface development, researchers wanted to understand how the Hobbit’s skull behaved while he ate his food.
However, thousands of years of fossilization had left his skull – the only one found to date – damaged and deformed. Before they could test it, the researchers had to restore it as close as possible to its original form. Collaborators from the Italian University of Bologna created a 3D virtual model, built from X-ray CT scans, digitally filling in missing pieces to reconstruct what the Homo floresiensis skull might have looked like as it roamed the island 100,000 to 60,000 years ago.
From there, they used computer simulations and a technique called finite element analysis to give the virtual skull characteristics that mimic reality, such as the stiffness of the bones and the pulling action of the muscles. Then they had the virtual skull crushed with its back teeth – bicuspids and molars – and analyzed the forces at work with each bite, essentially subjecting it to a digital crash test.
The researchers mapped the strains in their digital model of the Hobbit’s facial bones during the bite, comparing the results to similar simulations for earlier human relatives called Australopiths who lived around two to three million years ago in Africa. , as well as chimpanzees and humans living today.
The team determined that the Hobbit’s bite could have exerted a force of around 1,300 Newtons, comparable to the bite power of modern humans and many of our extinct cousins. But if he had bitten too vigorously on a hard nut or a large piece of meat, the results suggest that Homo floresiensis would have been more at risk than our human ancestors of forcing the bones of the face or of dislocating the joint or the jaws. lower and upper meet.
“We don’t really know what Homo floresiensis was eating,” said first author Rebecca Cook, a doctoral student in evolutionary anthropology at Duke. Wear patterns on the teeth, combined with pygmy elephant bones and other animal remains found in the same cave where the Hobbit was found suggest he ate at least some meat.
But the results suggest that extremely hard or leathery foods, which wouldn’t have been a problem for an Australopath to gnaw or crack, could have given the Hobbit a TMJ headache.
“Similar patterns are seen in modern humans,” Cook said.
Millions of years of human evolution have given us smaller teeth and lighter skulls, because cooking our food, slicing and pounding it with stone tools, and probably also eating meat, made skulls useless. oversized.
But years after the Hobbit’s discovery, his facial features remain a puzzle. His skull had a curious mix of features, some of which – like its heavy lower jaw – are similar to our older, more ape ancestors, while others – like its delicate little face – resemble humans today.
“This can confuse the location of this species in the family tree of evolutionary hominid relationships,” Cook said.
The new study suggests that this shift to smaller faces, weaker bites, and sore jaws evolved early, before the common ancestors of Homo floresiensis and modern humans went their separate ways.
Justin Ledogar, Duke researcher and lead author of the study, says the next step is to perform similar analyzes on the fore members of the genus Homo, including Homo erectus. The first hominid known to use fire and cook food, this species also had smaller teeth, jaws, and faces than previous hominids, and some believe it is the ancestor of Homo floresiensis.
The researchers say the work could help answer lingering questions about the origin of Homo floresiensis, how it lived and how it fits into the human evolutionary tree.
“This study is just one small piece of a much bigger puzzle,” Cook said.
This research was funded by the American Association of Physical Anthropology and Duke University, as well as grants from the European Union’s Horizon 2020 Research and Innovation Program (724046 SUCCESS) and the National Science Foundation of United States (NSF-BCS-0725126).