Combining Morphology and Palaeogenomics to understand the Status and Contribution of Mules to Roman Equine Populations in Austria and Germany.

在进化论和文化研究中，物种间杂交是一个相关的话题。在这方面，考古、图像和文字资料表明，数千年来，人类一直在杂交野生和家养的马科成员。本研究的重点是骡子，即公家驴与母马的杂交。由于所谓的杂种优势效应，骡子比亲本种群中的任何一个都更有效，特别是作为劳动动物，根据古典来源的说法，骡子是在数量上繁殖的。然而，仅根据牙齿和骨形态特征在古动物群组合中识别骡子(和其他马种)是有问题的，并且容易在观察者之间产生相当大的差异。因此，应用传统的形态学方法可能不是很有效地充分说明骡子在古代文化中的作用。本研究旨在阐明当地的饲养实践以及骡子对前罗马和罗马时代在德国东南部和奥地利开发的马群的贡献。它将应用标准形态学、几何形态测量学(GMM)和古代DNA分析相结合的多学科方法，以检验几个假设，即(H1)骡子代表着德国Raetia省、Noricum省和上潘诺尼亚省(奥地利)罗马化进程的标志，(H2)在阿尔卑斯山分水岭以北，没有进行公驴(驴)和母马(马)之间的杂交，这意味着动物必须从阿尔卑斯山以南已经建立杂交的地区进口，和(H3)在拉提亚的罗马兵役中对马的高需求不仅需要从其他地方进口，而且涉及到从罗马之前的当地人口中繁衍出当地马种的繁育努力。从方法论的角度来看，我们的项目期望建立一个可靠的遗传和GMM管道，系统地追踪马匹考古组合中的F1杂交后代，从而能够验证基于标准形态分析的鉴定。通过比较不同方法的结果，还可以量化在只能进行标准形态分析的情况下识别杂交种的准确度。总而言之，我们预计，这里提出的综合方法将开辟更多的场所，解决马匹杂交在过去社会中迄今被低估的作用，同时显著提高我们对阿尔卑斯山以北罗马帝国骡子的文化、经济和军事历史的了解。

In evolutionary and cultural studies, interspecies hybridisation is a relevant topic. In this respect, humans have been crossbreeding wild and domestic members of the family Equidae since millennia, as illustrated by archaeological, iconographic and written sources. In focus of this study is the mule, the cross between the male domestic donkey and the mare. Being more effective than either of the parental stock, elicited by the so-called heterosis effect, mules were particularly valued as labour animals and according to Classical sources bred in numbers. However, identifying mules (and other equid hybrids) in archaeofaunal assemblages based solely on dental and osteomorphological features is problematic and prone to considerable inter-observer variation. Consequently, application of traditional morphological methods might not be very efficient to specifying adequately the role of mules in ancient cultures.This study aims at elucidating local breeding practices and the contribution of mules to the equid populations exploited in southeastern Germany and Austria in pre-Roman and Roman times. It will apply a multidisciplinary approach combining standard morphology with Geometric Morphometrics (GMM) and ancient DNA analysis in order testing several hypotheses, namely that (H1) the mule represents a marker for the process of Romanization in the Provinces Raetia (Germany), Noricum and Upper Pannonia (Austria), (H2) north of the Alpine divide hybridization between male donkeys (jackass) and female horses (mare) was not practiced, implying that animals had to be imported from regions south of the Alps where cross-breeding was already established, and (H3) the high demand for horses in Roman military service in Raetia not only necessitated imports from elsewhere but involved breeding efforts with local horse lineages descending from pre-Roman local populations. From a methodological viewpoint our project expects establishing a reliable genetic and GMM pipeline for tracing systematically F1-hybrids in equine archaeological assemblages, thus enabling to validate identifications based on standard morphological analyses. By comparing the results of the different approaches it will also be possible to quantify the degree of accuracy for recognizing hybrids in cases where only standard morphological analyses can be performed. In sum, we expect that the combined approach proposed here will open up additional venues to address the hitherto underestimated role of equine hybrids in past societies whilst significantly enhancing our knowledge of the cultural, economic and military history of the mule in the Roman Empire north of Alps.