Ancient DNA refines taxonomic classification of Roman equids north of the Alps, elaborated with osteomorphology and geometric morphometrics

27.05.2022

New publication of WoBio member Elmira Mohandesan in the Journal of Archaeological Science.

Abstract

Hybrids of horse and donkey, which have been valued in the Mediterranean basin since the Iron Age, became integrated into the animal world north of the Alps in the course of Romanization. Until now, however, their true contribution to the economic and military life in the northern Roman provinces Raetia, Noricum and Upper Pannonia (southern Germany, eastern Switzerland and Austria) has remained unknown in the absence of robust identification methods based on morphometric approaches. We confronted morphological identification of 405 equid specimens collected in the Late Iron Age (Celtic) (∼2nd – 1st century (c.) BCE) and Roman (∼1st – 5th c. CE) archaeological contexts with their ancient DNA signatures. Our multi-method study demonstrates that although ancient DNA and morphological approaches (including standard osteomorphology and geometric morphometrics) provide overall >85% matching results, in the case of hybrid animals, the extent of overlap with ancient DNA drops to ≤52%. Out of five skeletal elements studied here (mandibular premolars and molars, metapodials, humeri and tibiae), only premolar mandibular teeth (P3, P4) provide good enough accuracy in hybrid classification (89%) based on geometric morphometrics, making it the preferred element and method in future zooarchaeological studies, when ancient DNA data is not available. Moreover, our data show that, although not yet present in the preceding Iron Age, one in six equids in Roman times is a mule, suggesting a strong Mediterranean influence on the use of equids in daily life north of the Alps.

More about the article

Sharif, M. B., Mohaseb, A. F., Zimmermann, M. I., Trixl, S., Saliari, K., Kunst, G. K., ... & Mohandesan, E. (2022). Ancient DNA refines taxonomic classification of Roman equids north of the Alps, elaborated with osteomorphology and geometric morphometrics. Journal of Archaeological Science, 143, 105624.

Click here to get the full paper

 

 

 Back
Accuracy is represented for five skeletal elements, from left to right: humerus, femur, molar, premolar and tibia. On the right, the position of each skeletal element is highlighted on horse skull (top) and post-cranial skeleton (bottom). Classification accuracy is very high (90-100%) for horses, independent of the method. It is much lower for hybrids, with the lowest accuracy for humerus (15-25%) and tibia (35%) and the highest accuracy for metapodial (55-60%), molar (60-70%) and pre-molar (65% for traditional morphometrics, 90% for geometric morphometrics).

Comparison of classification accuracy for equids (horse or hybrid) between two morphometric methods (GMM, geometric morphometrics; sMOR, standard morphometry), for five skeletal elements. Classification accuracy is very high (90-100%) for horses, independent of the method. It is much lower for hybrids, with the lowest accuracy for humerus (15%) and tibia (35%), and about 60% accuracy for the other bones. A striking exception is premolar, with a much better accuracy for geometric morphometrics (90% instead of 65%). From Sharif et al. (2022) Journal of Archeological Science.