2-Million-Year-Old Fossils Reveal How Our Ancestors Heard Sounds

Early hominins heard the world very differently than modern humans, according to a recent study published in the journal Science Advances.

Researchers at Binghamton University examined the fossilized ear bones of two early hominins from South Africa, A africanus and P. robustus, which lived between 3.3 million and 1.8 million years ago. The fossils included tiny middle ear bones called the ossicles, which shed light on the auditory abilities of our very early anscestors. The researchers used computerized tomography scans to virtually reconstruct the ears of the early hominins.

"They didn't hear as well as humans, and they are more like chimps," said Rolf Quam, an anthropologist at Binghamton University and one of the study's authors, via The New York Times.

However, researchers did find that the two species were more sensitive to close-range sounds than humans and chimpanzees, at between one and three kilohertz.

"They were almost like superhumans in this range," Dr. Quam added. "They could hear softer sounds than we could." 

In fact, based on the study findings, researchers noted how their heightened sensitivity to sound allowed them to make vocalizations to one another from up to 75 feet away in the open savanna.

"Compared with chimpanzees, both early hominin taxa show a heightened sensitivity to frequencies between 1.5 and 3.5 kHz and an occupied band of maximum sensitivity that is shifted toward slightly higher frequencies," Quam said.

The researchers also examined the auditory abilities of early humans in northern Spain who lived close to 400,000 years ago. Findings revealed that their hearing was similar to that of modern humans. 

Next, researchers hope to determine how hearing went from a chimp-like pattern to a more human-hearing pattern.

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