Researchers from a study published in the journal Science Advances discovered that Australopithecus africanus and Paranthropus robustus were very sensitive to close-range sounds compared to modern humans and chimpanzees.

The study focused on going further in the research of the auditory abilities of human ancestors two million years ago by examining fossils with tiny middle ear bones called the ossicles.

According to the research, the Australopithecus africanus and Paranthropus robustus were very sensitive to close-range sounds compared to humans and chimpanzees. Credit: North Carolina School of Science and Mathematics

In order to do so, the team of researchers virtually reconstructed the ears of the hominids. They found that they were capable of hearing softer sounds and in a larger distance, compare to the current auditory ability humans and chimps have.

According to Rolf Quam, from Binghamton University’s Department of Anthropology, human ancestors could hear sounds from others that were 75 feet away from them, since their sensitivity to sounds ranged from 1.5 to 3.5 kilohertz.

Other results showed that these species could have used what it’s called as “voiceless consonants” because the vocal chords remain still when these are produced. It includes the sounds of the letters ‘K,’ ‘T,’ ‘Th,’ ‘F’ and ‘S.’

“They certainly could communicate vocally,” Quam said in a statement, according to Live Science. “All primates do, but we’re not saying they had fully developed human language, which implies a symbolic content.”

Previous researchers suggested that these species could have lived either in the jungle or at a savanna. These vocalizations would have been harder to hear in the dense jungle, so they probably lived in an open habitat at the time.

“It turns out that this auditory pattern may have been particularly favorable for living on the savanna. In more open environments, sound waves don’t travel as far as in the rain-forest canopy, so short-range communication is favored on the savanna,” Quam said.

As the evolutionary theory showed, human ancestors had to adapt to lifestyle changes, which is why their hearing ability changed after 5 to 7 million years. There is still an open question about how hearing has changed from the chimp-like pattern, which is the one human ancestors had, to the human-hearing pattern.

Source: Science Advances