Differentiation of Bovinae teeth from the Portel‑Ouest Mousterian cave (Loubens, Ariège, France) by near‑infrared spectroscopy and chemometrics

Abstract

The Portel site, located on the Pyrenean piedmont in France (Ariege), includes two caves: the Portel‑Est cave, famous for its mainly Magdalenian cave paintings, and the Portel‑Ouest cave corresponding essentially to a Mousterian habitat (layers L to B1a: 135,000 to 36,300 years BP ; Ajaja, 1994, Tissoux, 2004). Excavations over five meters deep of stratigraphy carried out in the Portel‑Ouest by Joseph and Jean Vezian between 1949 and 1987 revealed 33 Neanderthal remains associated with over 200,000 vestiges. In these vestiges, we found 1483 Bovinae remains. In a previous paleontological study of similar vestiges, differentiating Bos primigenius from Bison priscus proved challenging. Considering morphological, biometric, or morphometric criteria, only 21% of the remains could be attributed to one of the two genera, with a clear predominance for Bison priscus. Thus 79% of the Bovinae remains could not be attributed to one or the other of the two genera, either because they had composite forms or because they were too fragmented or worn to attempt a specific attribution. The aim of the present project is thus to develop and exploit the rapid tool of near infrared spectroscopy to discriminate between these genera, focusing on the teeth. Each tooth in the database was scanned with a near‑infrared spectrometer. For 53 teeth, the database containing the infrared spectra was completed by the paleontological expertise designating the tooth as belonging to Bos or Bison. Chemometric tools were then used to build a model to assign the tooth to a genus, according to its infrared spectrum. In a final step, the model was used to predict the genus of 76 teeth that could not be assigned to the Bos or Bison genus by paleontologists. This step provided a projection of the animal population living at that time at Portel site. Finally, the results were compared with paleogenetic analyses.