Geographical variation in the size and shape of the European aurochs (Bos primigenius)

Highlights

• A wide-ranging study of aurochs biometry, providing an overview of its morphological variation across Europe.

• We propose a set of ‘standard’ measurements from a Pleistocene aurochs population.

• A south-north body size cline is detected for aurochs from Marine Isotope Stage 9 and during the early Holocene.

• Tentative evidence for a west-east body size cline is also presented during more recent periods.

• Highlights the importance of using geographically relevant comparative data to identify aurochs remains.

Abstract

The aurochs (Bos primigenius) is generally agreed to be the wild ancestor of domestic cattle (Bos taurus) and an in-depth knowledge of this animal is therefore key to research exploring human–cattle interactions, and the origins and spread of cattle domestication. Domestic cattle are smaller than their wild ancestors, but there is also a degree of overlap between the two species, which means that distinguishing them can be problematic. However, previous analyses of aurochs morphology have generally been patchy, and do not provide a picture of aurochs variation across Europe according to environment, climate and geography. As a consequence, zooarchaeologists often refer to comparative biometrical data from geographical areas and time periods which may not be suitable for identifying remains from their study area. This paper presents results from a wide-ranging study of aurochs biometrical data, in order to provide an overview of its morphological variation across Europe, and highlight the importance of using geographically and climatically appropriate comparative data when attempting to identify and interpret the significance of aurochs remains. We also propose a set of ‘standard’ measurements from an aurochs population excavated at the site of Ilford (Essex, UK) dated to Marine Isotope Stage 7 with the hope that they will be of use to others seeking a suitable standard for the biometrical analysis of cattle populations, especially when looking for the presence of wild specimens.

Introduction

The aurochs (Bos primigenius Bojanus, 1827), is generally accepted to be the extinct ancestor of domestic cattle (von Leithner, 1927, Cordier-Goni, 1938, Poplin, 1983, Chaix, 1994, Clutton-brock, 1999), and was one of the most widely hunted animals in European prehistory. Despite the remarkable importance of the animal for past human societies, most previous analyses of aurochs morphology have generally been brief and patchy. Those biometrical studies that have been carried out are often limited by small sample size and tend to focus on narrow geographical study areas. The geographical variation that has been demonstrated for a number of other mammal species (e.g. Albarella et al., 2009, Weinstock, 2000) suggests that information about aurochs size and shape gathered in one area may not be useful in other study areas.

Although domestic cattle are smaller than their wild ancestors, there is also a degree of overlap between the two species, which means that distinguishing them can be problematic. It is therefore important to identify the most relevant comparative aurochs biometrical data for each assemblage that we are dealing with. Greater knowledge about the variation that existed prior to the onset of domestication may be of assistance when attempting to identify early domestic animals, and the ability to trace fluctuations in body size and shape variation after domestication is also important to ensure accurate identifications are made. In addition, palaeogenetic works on the subject of cattle domestication, which have proliferated in the last twenty years or so (e.g. Bollongino et al., 2008, Edwards et al., 2007, Loftus et al., 1994, Mona et al., 2010, Scheu et al., 2008, Schibler et al., 2014), are dependent on the correct identification of cattle remains, and suffer from the uncertainty associated with our understanding of the morphometric characteristics of the aurochs and even the early forms of domesticated cattle.

The size of the aurochs has been a subject of debate for a long time. The large amount of variation it displayed initially confused researchers and for years led many to believe that there were two different forms of B. primigenius (e.g. Rütimeyer, 1867, Adametz, 1898). Later it became clear that the size differences were related to sexual dimorphism and therefore represent the male and female groups of one form (Frazer and King, 1954, Jewell, 1962, Degerbøl, 1963, Boessneck, 1957, Bökönyi, 1962, Degerbøl and Fredskild, 1970, Grigson, 1974).

In addition to the confusion caused by sexual dimorphism, the overlap in size between the aurochs and domestic cattle is also a complicating factor and much of the past work involving aurochs biometry has focussed on this issue (e.g. Degerbøl, 1963, Jewell, 1963, Grigson, 1969, Grigson, 1978 Degerbøl and Fredskild, 1970, Rowley-Conwy, 1995). Perhaps the best known work on the identification of aurochs remains is the study by Degerbøl and Fredskild (1970) which provides a large amount of biometrical data from Danish aurochs, and an overview of the body size of Danish aurochs in comparison to Danish Neolithic domestic cattle. This is an extremely useful resource, but may not be entirely relevant for the identification of remains from more distant geographical areas, even within Europe. Other reviews of the biometry of the aurochs within an individual geographical area have been undertaken on material from Sweden (Ekström, 1993), Britain (Jewell, 1962, Jewell, 1963) Spain (Estevéz and Saña, 1999); and Hungary (Bartosiewicz, 1999). In addition, various studies focussed on individual sites in other areas, such as Switzerland and Germany, have discussed the body size of the aurochs in detail (e.g. Stampfli, 1963, Street, 1999, Steppan, 1999, Steppan, 2003). However, most of these studies are generally restricted by small sample sizes and/or large chronological gaps in data.

Extensive studies of the variability of aurochs size and shape between different geographical areas are similarly rare. Zeuner (1963) suggested that aurochs in central Europe were on average larger than aurochs from south-west Europe; work by Jarman (1969) indicated that aurochs from north-west Europe were larger than those from the eastern Mediterranean area, Grigson (1969) suggested that aurochs from northern Europe were larger than those from Hungary, and work by Lasota-Moskalewska and Kobryn (1990) highlighted an east-west cline between aurochs from Central and Eastern European areas. The presence of a potential Pleistocene dwarf-form (B. primigenius sicilae) on the island of Sicily has also been discussed (Brugal, 1987, Mangano, 2011). All of these previous studies are restricted in their geographical scope and do not deal with large datasets, and despite the fact that they have highlighted the potential variation that may have existed between aurochs in different geographical areas of Europe, some studies have still attempted to investigate change over time by combining data from different climatic areas (e.g. Cerilli and Petronio, 1991).

Many of the studies that have focused on the morphological variation of the aurochs were also published before the appearance of the classic text by von den Driesch (1976) that defined hundreds of measurements that could be taken on archaeological animal remains. As a result there is not necessarily any consistency between different studies with regards to which or how measurements of aurochs bones were taken, and making direct comparison between different datasets may be unreliable.

This paper aims to present results from a wide-ranging study of aurochs biometrical data, in order to provide an overview of its morphological variation across Europe, and highlight the importance of using geographically and climatically appropriate comparative data when attempting to identify and interpret the significance of aurochs remains. This work was conducted as part of a wider PhD project (Wright, 2013) where, in addition to the geographical patterns presented in this paper, a thorough discussion of temporal changes within geographical regions, and the effects of individual measurements within individual assemblage patterns are presented.