Deaf diagnosis on 430,000-year-old human incorrect, 3D tomography reveals



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When the patient has been dead for around 430,000 years, it's a tricky diagnosis even for the best of hearing specialists, but an international research effort has cleared up a major lingering doubt on such cases.

Anthropologists can make quite a mess of studying societies in human prehistory if pathological conditions deducted from osseous remains lead to a misdiagnosis of a condition that would have social consequences; wrongly attributing deafness to a human ancestor, for example, leads to the conclusion that such a person would have suffered from the psychological stress, behavioural, and communication problems that affect people with hearing loss even today. Such confusion has not been uncommon, until a new study by international researchers involving New York's Binghampton University that shows the risks of basing hearing diagnoses on the state of found bones.

The team discovered that a particular individual found among remains in the Simo de los Huesos site in Spain—one of the 20th-century's major archaeological finds from the Lower Paleolithic period—had exostoses (extra bony growths) blocking parts of the ear canal, but that these are not evidence of hearing loss. The skull of the "Cranium 4" individual, one of the most complete found from the age and believed to be an early ancestor of the Neanderthal dating back 430,000 years, was given high resolution computed tomography (CT) scans to create virtual 3D models of the ear structures. Never before had such evidence been subjected to such detailed study. The 3D-model measurements were then entered into a software program that predicts hearing abilities based on the anatomical measurements of the ear.

"We were very surprised by the results and expected for this individual to have suffered some degree of hearing loss," said coauthor Manuel Rosa of the Universidad de Alcalá, Spain. The researchers have concluded that, despite this pathology in the ear canals, this individual did not suffer any appreciable differences in hearing compared to the healthy individuals from this same site.

"This study represents a novel approach to examining a well-known pathological condition, relying on medical imaging technology and virtual 3D models to assess the clinical implications of an ancient disease and to reveal new insights into the lifeways of our ancestors," said Binghamton University anthropologist Rolf Quam.

"Our results suggest caution in attributing auditory consequences to the presence of these bony growths," said lead researcher Mercedes Conde.

The researchers near-future plans involve looking at some ear bones—malleus and incus—from Cranium 4's middle ear cavity.

Source: ScienceDaily