New Historian

Hearing Ability of Early Humans Revealed in New Study

Left Human Ear (2)

<![CDATA[A new research study has revealed that human ancestors as they existed around two million years in the past had an ability to hear that has much in common with the modern chimpanzee – but with several indications that evolution was already having an effect. Led by Binghamton University anthropology assistant professor Rolf Quam, the international team of scientists and researchers reconstructed the hearing ability of several South African hominin fossils through the use of virtual computer simulations and CT scans of internal ear anatomy. According to the results, early species such as Paranthropus robustus and Australopithecus africanus had hearing abilities closely analogous to chimpanzees – with some minor but telling differences. Human hearing is differentiated from the majority of other primate species by being able to detect sound frequencies between 1 kHz and 6 kHz – the range in which most spoken languages reside. Other primates – such as chimpanzees – have hearing that is less sensitive in this range, something that has been confirmed in modern laboratory experiments, Quam said in a statement issued by Binghamton University. This initial data led researchers on a quest to discover when human ancestors first began to evolve the ability to hear at a wider range than our evolutionary cousins. Quam and the rest of the research team had conducted studies into 430,000 year old hominin fossils found in northern Spain, specifically from the Sima de los Huesos dig site. These Sima hominins – thought to be ancestors of Neanderthals – had hearing that was practically identical to modern humans. In comparison, the two million year old specimens from South Africa were closer to a modern chimpanzee’s hearing capacity. In the older, two million year old fossils, these early hominins had exceptional hearing at frequencies of 1 kHz to 3 kHz, and would have been able to hear better than either chimpanzees or humans in that range. The researchers said that this could have been an evolutionary adaptation for savanna life, as the open environment left little for sound waves to bounce off and echo, cutting the effective range of sound – this would have made the hearing range of these hominins ideal for short-range savanna communication. While Quam wouldn’t go as far as to say that this means these early hominins used language to communicate, he did say that vocal communication – something in which all primates engage – could have been common among these human ancestors. He also made it clear that research into the diet of these species – which included as much as half of their resources sourced from open environments – revealed that they spent large amounts of time in savanna-like regions. Most anthropologists agree that hominins at such a remote period of the past would not have had the physical capacity for language, both as a result of their limited cranial capacity and also of the limitations of their ability to vocalize and create the complex sounds associated with a spoken language. However, Quam remarked that the research he and his team have been engaging in has the potential to shed some light on this subject, as the ability to hear is intertwined with the development of language. For more information: Image courtesy of Wikimedia Commons user: David Benbennick]]>

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