Pinpointing when language became a prevalent trait during human evolution has been tricky. Last fall we read a paper which documented that Neandertals have the same FOXP2 sequence as modern humans. FOXP2 is a transcription factor associated with language. Two recent papers have shown that chimpanzees and humans have very similar structures in the brain that function in processing and producing sound. And despite the fact that several non-human apes have well known, documented histories of comprehending and communicating in sign language or with language boards, there has not been a consensus on when language definitively arose.
Rolf Quam, of the American Natural History Museum, along with several other colleagues have been investigating this issue. He’s been looking at the ear bones of Homo heidelbergensis, and he thinks they were capable of hearing sounds similar to how people do today. In other words, their ear bone anatomy is remarkably similar to modern Homo sapiens, despite the fact that Homo heidelbergensis is not directly related. The team reported their findings July 3 in Paris during the Acoustics ’08 conference.
From the press release,
“The skulls are from a site in Atapuerca, Spain called Sima de los Huesos, or “pit of the bones.” The Atapuerca research team, which includes members from many disciplines and universities, used CT scanning of the skulls to reconstruct the size and shape of the ear canals, Quam says.
The length of the ear canal determines what frequencies of sound waves resonate, and are therefore heard more easily, says Sunil Puria of Stanford University, who models hearing patterns from ear structure.The geometry of the ear canal reveals that the hearing patterns of H. heidelbergensis overlapped with those of modern-day humans. Both modern people and the ancient hominids have especially sharp hearing in the 2 kilohertz to 4 kilohertz frequency range, where much of the sound energy of spoken language is transmitted….
…The results don’t necessarily show that the ancient humans could speak, Quam says. “We’re saying that the ear changed for some reason and that those changes facilitated the possibility of language development,” he says.”
Like in modern humans (shown in solid blue), the ear canal of H. heidelbergensis (shown in red and magenta lines) had a peak in auditory sensitivity in the frequency range from 2 kilohertz to 4 kilohertz, where much spoken information is transmitted. Chimpanzees (shown in solid green) have a dip in sensitivity in that range.
All this really shows is that H. heidelbergensis could hear in the frequency range as modern humans. While I think it is very possible H. heidelbergensisis communicated, this research can not indicate that they used their ‘modern ear anatomy’ for anything special.