Figure 1

Christian improvement of Portuguese
cattle following the “reconquista”
evidence based on osteometry and molecular sexing
Davis SJM1,*, Svensson E2, Ginja C3,4, Detry C5, Amorim IR6, Gotherstrom A2, Albarella U7, Pires AE3,4,*
1Instituto
de Gestão do Património Arquitectónico e Arqueológico, Laboratório de Arqueociências, Lisboa, PT; 2Uppsala University, Department of Evolutionary Biology, SE; 3Instituto Nacional dos Recursos
Biológicos, Grupo de Biologia Molecular, Lisboa, PT; 4Universidade de Lisboa, Faculdade de Ciências, Centro de Biologia Ambiental, Lisboa, PT; 5Universidade de Lisboa, Faculdade de Letras, Uniarq – Centro
de Arqueologia, Lisboa, PT; 6Universidade dos Açores, Departamento de Ciências Agrárias – CITAA, PT; 7University of Sheffield, Department of Archaeology, UK
Introduction
Zooarchaeology, the study of animal remains from archaeological sites, attempts to reveal the way our ancestors interacted with animals. In a lineage of domesticated
animals like cattle, a size increase is generally assumed to reflect improvement. However, bulls are larger than cows so an average size increase could merely be the result
of a change in the sex ratio within samples from, say, more cows to more bulls/steers. The cattle teeth and bones from 15th Century Beja (Alentejo, Portugal) are larger
than remains from earlier (Moslem period) sites. Does this size increase reflect improvements to cattle undertaken by the Christians following the
„reconquista‟?
The degree of sexual size dimorphism in cattle bones is poorly understood mainly because there are few entire adult cattle skeletons (male and female) in museum
collections.
Aims
1. To genetically determine the sex of archaeological cattle bones (metacarpals) from Beja to show that the post-Moslem size increase of Portuguese cattle is a real size
change and not one due to sex-ratio variation; 2. To use these ‘sexed’ metacarpals to determine which of the measurements that zooarchaeologists take can be used to
osteometrically determine gender; 3. To revisit the Medieval and post-Medieval cattle at Launceston Castle (Cornwall, England) to determine whether the sex ratios at that
site changed and how this relates to what we know about the development of cattle husbandry in England at that time.
Material & Methods
A total of 95 metacarpals were measured from Moslem Santarém and Silves, and Christian (15th century AD) Beja. Seven measurements were taken as shown in Figure 1.
DNA was extracted from a subset of 21 measured metacarpals from Beja (100 mg). A sex discriminating single nucleotide polymorphism (SNP) in the ZFXY gene was
genotyped by pyrosequencing (Svensson et al. 2008). For gender determination there are two homologous genes ZFX and ZFY located on the X and Y chromosomes,
respectively (Aasen 1990). In bovines, a SNP differentiates between males and females. Both females and males have a T in the ZFX gene, but the males have a C instead of T
on ZFY (Werner et al. 2004; see Fig. 2).
Picture © Alexandre Vaz
♀
Figure 1 – Measurements
generally taken on cattle
metacarpals
♂
Results
Figure 2 – Pyrograms showing the
sex discriminating SNP. Females are
T/T while males are T/C
The metacarpal measurements from Beja, plotted as a histogram, show two peaks (Fig. 3). The bimodal distributions of BFd in the
Santarém and Beja samples were interpreted in terms of gender (Davis 2008) – the smaller being females and the larger males.
The ancient DNA-sexing of metacarpals has confirmed this interpretation (see top graph in Fig. 3).
Of the various measurements and indexes plotted as scatter diagrams, the best discriminators between the sexes (confirmed through DNA
testing) are DEL versus BFd (Fig. 4) and the indexes SD/GL versus BFd/GL (Fig. 5).
Plotting these indexes for the Medieval and post-Medieval cattle from Launceston indicates that the Medieval sample of adult cattle included
both sexes – perhaps reflecting a relatively unspecialised management of this species. However, the majority of the post-Medieval cattle are
females with only one adult bull (Fig. 6). This may reflect specialised cattle management with most bulls being slaughtered young for veal
and cows kept for milking. [The Medieval to post-Medieval at Launceston also saw a size increase of cattle and a marked shift of culling
with a considerably higher percentage of young cattle slaughtered – probably for veal (Albarella & Davis 1996)].
Figure 3 – The osteometry of cattle metacarpals indicates that both
male and female cattle increased in size after the Moslem period
What motivated this increase – the need for power, or meat, or both?
♂ ♀
Figure 4 – DEL versus BFd. Note the
separation of males from females (via size).
The greater spread of males could be due to
the mixture of steers and bulls
Figure 5 - SD/GL versus BFd/GL. Note the
near complete separation of the sexes (via
shape)
Figure 6 - SD/GL versus BFd/GL indexes for
Launceston Medieval and post-Medieval cattle
metacarpals
Conclusions
1. DNA-sexed metacarpals from Beja confirm that the bimodal distribution of osteometric measurements at that site (probably also at
Moslem Santarém) represent cows and bulls/steers. Therefore, both female and male cattle increased in size after the Moslem period
– presumably reflecting Christian improvements of cattle in Portugal. Were cattle improved for their power for ploughing as well as
for their meat? 2. The measurements DEL versus BFd and the indexes SD/GL versus BFd/GL are useful for osteometric sexing of
archaeological cattle metacarpals. 3. A substantial change of the sex ratios occurred in cattle at Launceston between Medieval and postMedieval times which can be linked to increased specialization.
The
/
ratio in archaeological bones helps to
understand past animal husbandry practises:
In Medieval and post-Medieval Launceston adult cattle
there was a shift in the sex ratio from equal
representation of both sexes in Medieval times to a
predominance of females in post-Medieval times.
A more specialized husbandry based upon veal (young
males) and milk was adopted. This is in agreement
with historical evidence of cattle improvement in
England from the 16th century on (Trow-Smith 1957).
References: Davis (2008) J. Archaeol. Sci. 35: 991-1010 ; Svensson et al. (2008) J. Archaeol. Sci. 35: 942–946; Werner et al. (2004) Anim. Genet . 35: 44e49; Albarella & Davis (1996) Circaea. York. 12:1-156; Aasen E (1990) Biotechnology 8, 1279e1281; Trow-Smith (1957) A history of British livestock husbandry to 1700. London, Routledge and Kegan Paul
VI Encontro Nacional de Biologia Evolutiva, Lisboa, Portugal, 2010 // Research funded by FCT: PTDC/HIS-ARQ/100225/2008 & SFRH/BPD/20806/2004