This article describes an osteolytic odontogenetic lesion found on the mandible of a Neanderthal from the Middle Paleolithic site of Riparo Mezzena near the city of Verona (Italy). A pathology was revealed through X-ray and computerized-tomodensitometric examinations. This lesion was compared to present and sub-contemporary populations and indicates that it may have been of infectious origin, resulting from a bacterial invasion of the root canal of a coronal pulp exposure. The bacterial contamination may have resulted either from a traumatic fracture, a cavity, or extensive wear on the tooth.
Cet article présente une lésion ostéolitique odontogène observée sur la mandibule d’un fossile Néandertalien provenant du site Paléolithique moyen de Riparo Mezzena, près de la ville de Vérone en Italie. Cette pathologie a été mise en évidence par des examens radiologiques et tomodensitométriques. Par comparaison avec une lésion d’aspect similaire chez un patient actuel, l’étiologie de cette pathologie semble être d’ordre infectieux. Elle serait, sans doute, due à une invasion bactérienne de la cavité pulpaire à partir de la surface occlusale, par suite de la cassure accidentelle de la dent, ou d’une carie, ou encore d’une très forte abrasion.
One of the main challenges presented by the study of human fossils is in reconstructing their living conditions and behavior through detailed analysis of the elements represented by prehistoric fossils, above all the skeleton and teeth. In this article we examine a Neanderthal mandible from an extinct human fossil group that was present in Europe between 150.000 and 30.000 years ago. We provide evidence for an osteolytic lesion in a mandible, revealed during a systematic computerized-tomography scan of the mandible from the Neanderthal of Mezzena.
The site of Riparo Mezzena in northern Italy is located at 250 meters a.s.l, along a Middle Eocene limestone cliff on the northern side of the Avesa Valley, next to the city of Verona. The site, named after its discoverer, Franco Mezzena, was excavated by the Natural History Museum of Verona in the summer of 1957 under the direction of F. Zorzi and A. Pasa. During these excavations a series of layers of variable thickness were exposed, ranging between 1.5 and 1.7 meters, and at least three anthropogenic layers were identified (top-bottom: layers I, II and III). All the human remains (probably two individuals) were found in layer Ib. Results from the pedological, sedimentological and palynological analyses suggest the presence of a cold, continental climate associated with layer III, followed by a wet interval corresponding to the limestone surface between layers III and II. Layers I and II were marked by a continental climate, characterized by dry and cold phases (in correspondence with loess sediments) as well as humid phases (corresponding to concretions) (
The lithic industry has recently been the topic of a new study aiming to understand the interaction between humans and their environment (
The majority of human remains from Mezzena were found within level I. The human fossils include an incomplete mandible and 14 bone fragments, three of which belong to the post-cranial skeleton. From a morphological point of view, the thickness of the cranial fragments is remarkable. In view of their state of preservation and of the thickness of the bones, these fossil remains may have belonged to a single adult individual, although it is not possible to relate them to each other. The fragmentary state of the material allows only a limited anatomical study. However, among these pieces, fragments of the frontal bones suggest a very flat frontal bone similar to that observed on European Mousterian Neanderthals and, in particular, among the Italian Neanderthals (
In view of all the morphological features, the human remains of Mezzena are assigned to Neanderthals and confirm the prior diagnosis (
The incomplete mandible of Mezzena in which a pathology has been found is represented by a complete symphyseal region and a section of the mandibular corpus. The two rami and the left side of the mandibular corpus are broken. However, the symphysial region is complete. On its right side, the corpus of the mandible is conserved up to the level of the second molar.
No teeth remain in the mandible. (
Extensive destruction and pathological remodeling of the bone in the vicinity of the right premolar and molar teeth were revealed through X-ray and computerized-tomodensitometric examinations. X-ray analysis reveals a radiologically clear image, located on the lower edge of the mandible. In lateral view, it extends from the first right premolar to the first right molar and is composed of three parts: two individualized lobes in the half lower horizontal segment, a mesial lobe, situated in the area of the first right premolar, and a more distal one, extending from the second premolar to the first right molar and 1 vertical “trajectory” extending from the alveolus of the second right premolar to the junction of the two lobes previously described, situated in the middle of the rising body on a vertical axis. The residual apex of the second right premolar may also be distinguished in the alveolus. Its position can be associated with an eviction in process (see supplementary on line material,
This type of osteolytic lesion in the Neanderthal mandible of Mezzena corresponds to a benign bone tumor of dental origin (
The Mezzena jaw belongs to the Neanderthals that inhabited a vast geographical area during the Middle and Late Pleistocene, extending from all over Europe to the Middle East, western Asia and southern Siberia. The Mezzena mandible presents an odontogenic osteolytic lesion that led to extensive destruction and pathological bone remodeling in the vicinity of the right premolars and first molar teeth. This lesion is evidenced by the fistulian intra-osseous path and is certainly the result of an infection developed in the premolar.
Regarding the cause of this pathology, we note that the residual root fragment is situated close to the alveolar rim and is probably in the process of eviction. This observation makes it possible to exclude the hypothesis of bacterial proliferation around the dental root originating from a periodontal trauma, which would have been illustrated in the X-ray image by a “glove finger-shape” osseous loss. Thus, the bacterial invasion that induced this osteolytic lesion was probably exclusively of endodontal origin. This hypothesis is corroborated by the complete exposure of the tooth pulp to bacteria due to absence of the tooth crown.
Because a great number of teeth are absent and were missing
It is interesting to note that the Mezzena mandible shows an oral pathology that is frequently observed among both Neanderthals and hunter-gatherer human populations (
At present, there is no clear etiological diagnosis for the causes of the pulp exposure in the Mezzena mandible. This exposure may have resulted from a traumatic fracture, from a cavity, or from extensive wear on the tooth. All these causes are documented in Neanderthals.
Indeed, traumatic breaks have been observed on fossil teeth and are found on at least two French Neanderthals: Arcy 9 and La Quina 5. For a long time, no cavities were recognized in Pleistocene populations and it is only during the last two decades that cavities have been observed in Neanderthals. Thus, two cavities have been described on two Neanderthal teeth from the same French site (Bau d’Aubesier) (
In view of the extensive wear found in particular on Neanderthal teeth and, more generally, on those of hunter-gatherer populations, it would be tempting to support the hypothesis that the loss of the premolar crown on the mandible of Mezzena was most probably caused by dental abrasion.
The mandible of a Neanderthal from the Middle Paleolithic site of the Riparo Mezzena presents an osteolytic odontogenetic lesion. This pathology was revealed through X-ray and computerized-tomodensitometric examinations. Similar lesions have been observed among present and sub-contemporary populations and indicate that the lesion of the Mezzena specimen may have been of infectious origin, resulting from a bacterial invasion of the root canal due to coronal pulp exposure. There is no clear etiological diagnosis concerning the causes of the pulp exposition in the Mezzena mandible. Available data known for Pleistocene fossils and, in particular, for Neanderthals, indicate that the etiology of the pulp exposure in the Mezzena Neanderthal mandible may have been due to breakage of the tooth, to a cavity, or to extensive wear.
This research is a part of the project on the “Human fossils of the Verona area” coordinated by one of the authors (L.L.). We would like to thank M. Pozzi Mucelli, G. C. Mansueto, D. Malagò, G. Troiani and G. Genovese of the Dipartimento di Diagnostica Clinica, University of Verona, for providing invaluable assistance in the X-Ray and CT Scan analysis of the human fossil remains. We thank the Chief Editor Michel Laurin and the anonymous reviewers who contributed to the improvement of this manuscript.
X-ray of Mezzena mandible in vestibular view.
Radiographie de la mandibule de Mezzena, en vue latérale. X-ray of Mezzena mandible in lingual view.
Radiographie de la mandibule de Mezzena, en vue linguale. Frontal sections of the mandible at the level of the lesion.
Images scanner de coupes frontales de la mandibule au niveau de la lésion. Panoramic X-ray of a present day similar osteolytic lesion.
Radiographie panoramique d’une lésion ostéolytique actuelle similaire.
The Mezzena Mandible; top left: superior view; top right: inferior view; bottom left: lateral view; bottom right: frontal view.
La mandibule de Riparo Mezzena ; en haut à gauche : vue supérieure ; en haut à droite : vue inférieure ; en bas à gauche : vue latérale ; en bas à droite : vue frontale.