Neandertals had big mouths that they were able to open unusually wide, new research has determined.

A recent study found that a combination of facial structure, forward-positioned molars, and an unusually large gap between the vertical parts of the back of the jaw allowed Neandertals (also spelled Neanderthals) to gape widely.

Modern humans and our direct ancestors don't have these traits, the researchers note.

But the team was unable to measure exactly how far Neandertals could open their mouths.

"This ability is connected to the length of the muscle fibers, which, of course, we don't have," said study co-author Yoel Rak, a professor of anatomy at Tel Aviv University's Sackler Faculty of Medicine.

Image
©Yoel Rak
A Neandertal skull found in the Lower Galilee region of Israel displays a wide gap between the vertical part of the jaw and the wisdom teeth.

This gap, combined with other unique facial structures, allowed Neandertals to open their mouths very wide, although researchers are still not sure why they had this ability.


Rak and colleague William Hylander, an expert on jaw biomechanics at Duke University, presented their findings last month at a meeting of the Paleoanthropology Society in Vancouver, Canada.

The scientists believe the large space behind Neandertals' molars created a geometry that allowed them to take extremely large bites.

This is perhaps an adaptation to the size of the food Neandertals ate, the researchers said, although they caution that the exact reason for the wide gape remains an enigma.

"Why were they able to do this?" Rak asked. "This is something that only a time machine could help us answer."

Skull Evolution

Neandertals lived in parts of Europe and Asia for more than 400,000 years, then disappeared some 30,000 years ago.

The omnivorous species had an extremely varied diet - from vegetation to reindeer - and they knew how to butcher and cook meat.

"They didn't have to put a whole [animal] leg in their mouths," noted Alan Mann, a physical anthropologist at Princeton University who did not participate in the new research.

"I would suspect that the Neandertals were probably as adept as we are in cutting their food into manageable sizes," he said.

Mann believes a large mouth structure may not have been exclusive to Neandertals but was also present in earlier human species.

Instead of eating habits, the change in gape size may be due more to the evolution of the skull: as the braincase expanded, the face moved under it, he said.

"What has changed is the architecture that we begin to see in modern humans, where the face and the braincase have different kinds of structural relationships," he said.

"This has produced a change in our ability to open our mouths."