Periodic Reporting for period 1 - N-SPIRE (The Neanderthal nose: reconstruction of shape, function and adaptations)
Période du rapport: 2022-09-01 au 2024-08-31
Neanderthals are among the most fascinating topics in paleoanthropology for their relationship with our species. In addition, their evolution and adaptation have become topics increasingly relevant as a case study of human response to climate: the current global climate change brings along a discussion on the biological response of populations to it and the possible cultural, demographic, and ecological consequences. In this concern, the species Homo neanderthalensis, which had to face the harsh, cold conditions of the Late Pleistocene in Eurasia, generated a longstanding debate among experts about their possible adaptation to cold climate. This focused in particular on the mid-facial prognathism, a configuration of the maxillae and the nasal region, characterised by a forward projection of the large nasal opening, which represents one of the most defining characteristics of the species. Some authors have linked such a peculiar morphology to a cold climate adaptation of the Neanderthal nose. Yet, the function of the upper respiratory tract in Neanderthals is an elusive topic: in the human fossil record, but also archaeological collections, the inner structures of the nasal cavity are often lost due to their fragility. The project N-SPIRE intends to investigate this aspect thanks to the only preserved nasal cavity in the human fossil record: that of the Neanderthal skeleton from Altamura (southern Italy). In this exceptionally preserved individual from ca. 150000 years ago that is still preserved in the cave where it was found in the early ‘90s, the inner structures of the nasal cavity are complete and observable. The main aim of N-SPIRE is to use such unique evidence to settle the longstanding debate on the relationship between the Neanderthal face and climate. In addition, N-SPIRE will contribute to raising awareness of this exceptional yet overlooked specimen from Italy and of the Italian fossil record related to the Neanderthal lineage. Lastly, the data produced during N-SPIRE can contribute to further exploring the biological response of human populations to the changing environment.
Endoscopic technology has been used in the cave in previous studies by the candidate to acquire images of these anatomical details. The first objective of the project was to create a digital model of the anatomical structure to put in comparison with those of geographically sorted modern human populations, known for their adaptation to different kinds of climate. The method used for the creation of such a model from the photographic acquisition is photogrammetry. The task to perform was unprecedented since a shape like that of a cavity is difficult to reconstruct faithfully. Meanwhile, the candidate developed an open-access method in the R programming language to semi-automatically perform the virtual extraction of cranial cavities and the calculation of their volume (called Icex), for assessing the contribution to midfacial morphology of the functional regions represented by the nasal cavity and the paranasal sinuses. In parallel, the candidate had to be trained in methods and disciplines necessary to achieve the following objectives, specifically, methods for biomechanics, such as the Finite Element Analysis, to reconstruct the structures of interest and be able to study mechanic performances like the conditioning of the inspired air. Reconstruction of the soft structures of the nasal cavity and the respiratory performance represented the second objective, which has been delayed by the longer time necessary to obtain a good reconstruction of the bony cavity. The training at the secondment institution at the Department of Mechanical Engineering of the University College London, though has been, for the fellow, a chance to apply his method of assessment of cranial cavities to modern human samples and investigate the contribution of cranial cavities to the craniofacial growth and development in subadult samples. Such collaboration produced a series of works in major journals which consistently advanced the knowledge of the biomechanics of growth. In addition, with the newly developed method, the fellow could perform a study on the maxillary sinuses in fossil and modern humans, which has been presented at the 2024 meeting of the Palaeoanthropology Association in Los Angeles. These structures represent a problem for morphological analysis of their variable form and the rare completeness in fossil samples. By the use of Icex, observations could finally be done concerning their shape and volume, obtaining interesting results now aimed at the publication. The last objective was to analyse the morphological data of the nasal cavity along with paleoenvironmental proxies, to assess the impact of climate on the morphology. While this is underway for what concerns the simulations of the respiratory performance, it was done for what concerns the nasal cavity morphology. The fellow has used climatic variables to assess whether the morphology of the reconstructed nose for Altamura follows a trend recognisable in modern humans. The paleoclimatic data contributed to the morphological analysis in defining whether the nose of this Neanderthal individual shows evidence to be adapted to the conditions obtained for its geographical area and chronology. The results are now submitted for publication. In sum, N-SPIRE produced seven articles (of which two are currently in submission), eight contributions to scientific meetings with the fellow as the main contributor, and at least seven outreach events.
N-SPIRE contributed to bringing back the fossil skeleton from Altamura to the attention of both the scientific community and the general public. In addition, in the project were produced new methodologies to overcome the problems in the study of cavities like the nasal cavity and paranasal sinuses. In the first case, N-SPIRE provided the first data on the internal nasal structure of a fossil hominin and the base for the future modelling of respiratory performance in a fossil human species. In the second case, the first morphological analysis paired with an assessment of the volume of the maxillary sinuses identified group-specific patterns which provide interesting insights into the evolution of the Neanderthal facial morphology. In this concern, N-SPIRE also contributes to clarifying the causal relationship between the nose and midface in the species. Lastly, the application of the open-access methodologies devised for N-SPIRE to modern subadult samples helped clarify the contribution of the cranial cavities to the normal pattern of development. The outreach initiatives carried out for N-SPIRE could rely on the public interest in the topics of human evolution, particularly in Neanderthals, and were successful in bringing the themes of prehistory, human-environment interactions and the importance of the paleoanthropological heritage to the general public.