Morphometric Variation in Ancient and Modern Sus scrofa

1. Morphometric Variation in Ancient and Modern Susscrofa Joseph Owen

2. Is about pigs… Specifically how we tell wild pigs from domestic pigs This talk

3. What's being covered? • Why we study pigs • The inadequacies of Biometry • Geometric morphometrics • - The Basics – What it is • - The Advantages • - How is it being used

4. Pigs • One of the major domesticates • Used for fast meat production • First Domesticated somewhere in south-eastern Turkey 10,500-10,000 years ago

5. Pigs have been used as proxies to chart the spread of the Neolithic Revolution Larson et al 2007 used aDNA to distinguish between wild and Domestic What about those areas where there is no aDNA information? Utilise all forms of information Taken from Larson et al 2007. Pigs and the European Advance

6. Wild vs. Domestic • Traditionally wild and domestic pigs have been told apart with size • Rutimeyer (1860) first did this with molars from Swiss lake dwellings • Also applied to post-cranial skeletal material e.g. von den Driesch 1976 • Further methods include co-efficents of variation (Payne and Bull 1988) and Log Ratios (e.g. Albarella et al 2009)

7. Measuring size and not shape Wild pigs are not always bigger than domestic pigs (e.g. Island populations and insular dwarfism) Measurements represent an order of magnitude, e.g. greatest/shortest breath, depth or length No information of the geometry between points of measurements Size is only a rough guide to wild/domestic – its is hard to separate small wild from large domestic (see Albarella et al 2009) Biometrical Issues

8. Shape – Not Size • It has been noted empirically that animal shape changes as a result of domestication (see Arbuckle 2005) • But do we know how? • This project is attempting to quantify how the skull (chosen for its lower plasticity than the post cranial skeleton) changes with domestication • It will investigate genetic and epigenetic causes of intraspecific variation

9. Geometric Morphometrics (GMM) • Is a statistical technique that has been developed mainly over the last 10-20 years • Landmark GMM is based around the creation of a configuration of landmarks, each configuration representing a single skull • Each landmark is Biologically and Mathematically Homologus

10. GMM The Basics • Generalised Procrustes Analysis • This scales, locates and translates the configurations of landmarks relative to the average (or a set reference) configuration • As a result the only difference between each configuration of landmarks will be shape • Size can be re-introduced (and correlated with shape variables through uni-variant and multi-variant regressions)

11. GMM – The Advantages • Deals with shape • Results in data that may be used for multivariate statistics • Visualisation • The geometry of the shape is preserved, and the space between landmarks is represented by the ‘bending energy’ of the thin plate spline • This is based on the difference between configurations of shapes and

12. Methodology • 69 unilateral homologus landmarks have been chosen • 44 on the cranium and 25 on the mandible • Teeth although included are being investigated elsewhere • Projected sample set size is 400 – all ‘modern’ from museum collections, attempting to avoid products of intensive breeding

13. Principle Components Analysis • Is used to simplify results and reduce the degrees of freedom • It ranks co-variance factors according to how much variance each one describes • So the first principle component will describe the most variance, and the last the least variance • Each principle component is given an eigenvalue to show how much variance they describe

14. Error? • Based on O’Higgins and Jones 1998

15. Wild vs. Domestic PCA of right mandible

16. Wild vs. Domestic PCA of right cranium

17. Other Questions • What questions are being asked of the data? • How does the skull co-vary between wild and domestic and what areas of he skull co-vary most • Albarella et al 2009 notice a size change across Europe – can this be replicated? Also does climate affect shape? • Allometric (shape change related to size) and Ontogentic (shape change related to age) trajectories – a usefull study as it may reveal at what age shape differences between wild and domestic pigs emerge • Other questions include sexual dimorphism, Asymmetry, and links to the aDNA studies as being carried out by Greger Larson and Linus Girdland Flink et al

18. The Purpose • By working out exactly what is happening we may come to understand exactly why it is happening • May show which areas of the skull show most covariance • Highlight which factors affect shape the most • Will provide a baseline from which future analysis may draw upon

19. Visualisation • EVAN (European Visual Network in Anthropology) new software (due in the spring)

20. Bibliography • Albarella, U., Dobney, K., and Rowley Conwy, P., 2009 Size and Shape of the Eurasian wild boar (Sus scrofa) , with a view to the reconstruction of its Holocene history. Environmental Archaeology 14 (2) 103-136. • Arbuckle, S. Experimental animal domestication and its application to the study of animal exploitation in pre history. In Vigne, J-D, Peters, J. and Helmer, D. (eds.) 2005. The First Steps of Animal Domestication: New Archaeological Approaches. Proceedings of the 9th ICAZ Conference Durham. Oxbow Books. Oxford. 18-34. • Larson, G et al 2007 Ancient DNA, pig domestication, and the spread of the Neolithic into Europe. PNAS.15276-15281 • O’Higgins, P., and Jones, N., 1998. Facial growth in Cercocebus torquatus: an application of three dimensional geometric morphometric techniques to the study of morphological variation. J.Anat 193: 251-272. • Payne, S., and Bull, G., 1988. Components of variation in measurements of pig bones and teeth, and the use of measurements to distinguish wild from domestic remains. ArchaeoZoologia 2: 27-65. • Zelditch et al 2004 Geometric Morphometrics for Biologists: A Primer • With thanks to NERC, The Leverhume Trust, My Supervisors - Keith Dobney, Una Strand Vidarsdottir and Peter Rowley Conwy and also to the organisers of PZAF