Study: Neanderthals could perceive and produce human speech

March 1 (UPI) -- Neanderthals possessed the capacity to hear, process and produce human speech, according to a new survey combining CT scans and computer models.

For the study, published Monday in the journal Nature Ecology and Evolution, researchers used computed tomography scans to build 3D models of the ear structures in Neanderthals, Homo sapiens and Neanderthal relatives unearthed at Atapuerca, an archaeological site in Spain.

Computer algorithms developed by scientists in the field of auditory bioengineering helped researchers analyze the 3D models and estimate Neanderthals' auditory capabilities.

The findings suggest the origins of human language can be traced to our closest hominin relatives.

"This is one of the most important studies I have been involved in during my career," study co-author Rolf Quam said in a press release.

"The results are solid and clearly show the Neandertals had the capacity to perceive and produce human speech. This is one of the very few current, ongoing research lines relying on fossil evidence to study the evolution of language, a notoriously tricky subject in anthropology," said Quam, an anthropology professor at Binghamton University.

Of course, scientists can never know exactly how Neanderthals communicated, but by studying their adulatory capabilities, researchers were able to formulate informed inferences about Neanderthals' linguistic capacities.

The 3D modeling analysis showed Neanderthals could process sound frequencies up to up to 5 kHz. In other words, most of the sound frequencies produced by human speech were recognizable to the ears of Neanderthals.

The algorithms showed the hearing capabilities of Neanderthals at frequencies between 4 and 5 kHz were superior to those of the Atapuerca hominins.

Researchers were also able to use the computer models to calculate Neanderthals' occupied bandwidth, the frequency range that their hearing was most sensitive to. The wider the range, the more easily a species was able to distinguish between a diversity of sounds.

Models showed the occupied bandwidth of Neanderthals was more similar to the occupied bandwidth of modern humans than Atapuerca hominins.

"This really is the key," said lead author Mercedes Conde-Valverde, professor at the Universidad de Alcalá in Spain. "The presence of similar hearing abilities, particularly the bandwidth, demonstrates that the Neandertals possessed a communication system that was as complex and efficient as modern human speech."

The latest analysis also showed Neanderthals were likely capable of producing a range of consonants comparable to the verbal abilities of humans.

"Most previous studies of Neanderthal speech capacities focused on their ability to produce the main vowels in English spoken language," said Quam. "However, we feel this emphasis is misplaced, since the use of consonants is a way to include more information in the vocal signal and it also separates human speech and language from the communication patterns in nearly all other primates."

"The fact that our study picked up on this is a really interesting aspect of the research and is a novel suggestion regarding the linguistic capacities in our fossil ancestors," Quam said.

By documenting the shifts in the inner ear structures from Atapuerca hominins to Neanderthals to modern humans, researchers were able to trace the evolution of more fine-tuned hearing abilities.

The authors of the latest study suggest these changes evolved in response to a similarly advancing capacity to produce complex speech sounds.

Previous studies have shown Neanderthals were building fires, developing relatively sophisticated stone tools, producing cave art and engaging in burial rituals.

The latest findings suggest the speech and hearing capabilities of Neanderthals may have also been more sophisticated than previously estimated.