- Atapuerca: The world 'mecca' of the evolution of man
- Sima of the Bones.The first 'sanctuary' of Humanity
The skull of 'Agamemnon', one of the most important of 'Homo heidelbergensis' found in the Sima of the Bones of Atapuerca, was considered until now as the evidence of a case of the oldest known deafness. However, new and more precise research has shown that this hominid of 430,000 years ago could, despite certain bone irregularities, hear perfectly.
The study, published in the Journal of Human Evolution and led by Mercedes Conde-Valverde, from the University of Alcalá, used computed tomography techniques to create a three-dimensional model of the ear structures, from which, and thanks to a methodology developed by the Atapuerca team, it is possible to establish the listening abilities of the specimen.
In addition to shedding light, through the study of fossils of different periods, of the evolution of human listening, intimately related to the ability of language, the technique has now given a surprising result on the skull 4 of the Sima of Bones, known as 'Agamemnon': although until now the opposite had been thought, the hominid could hear.
"The scientific quality of a team is also measured by its ability to continually critically reassess its own previous results," said Juan Luis Arsuaga, Professor of Paleontology at the Complutense University of Madrid and co-director of the Atapuerca team.
The reason that had led to the equivocation was that, in fact, 'Agamemnon' suffered from irregular growth of the ear bones, what is known as exostosis or, more vulgarly, 'surfer's ear'. But the problem did not prevent him from hearing just as well as any of his contemporaries.
Ear exostosis is common in people exposed to cold water continuously, such as divers, swimmers or surfers, but also influences genetics and various external causes, such as wind or infections. In one way or another, the irregularities that developed the skull of 'Agamemnon' were, in addition to insufficient to prevent hearing, a particular case.
"It is the only one among more than a dozen skulls that can be studied, which seems to indicate that the pathology is not due to any environmental factor to which the entire population was exposed," says Conde-Valverde.
Evolutionary line of hearing
The technique to identify auditory abilities goes beyond the analysis of specific cases, since it has allowed to establish an evolutionary line from primates such as chimpanzees to modern humans, passing through various species, such as 'Homo heidelbergensis'.
"The results that we have obtained in previous investigations show that the humans of the Sima of the Bones had an auditory pattern similar to that of our species and very different from that of the chimpanzees, although it was not exactly the same as that of 'Homo sapiens'. studies show that the humans of the Sima of the Bones could hear with great precision the majority of the sounds that compose the human languages ", analyzes Conde-Valverde.
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