Journal of Archaeological Method and Theory

, Volume 22, Issue 1, pp 58–143 | Cite as

Understanding Inter-settlement Visibility in Iron Age and Roman Southern Spain with Exponential Random Graph Models for Visibility Networks

  • Tom Brughmans
  • Simon Keay
  • Graeme Earl


Long-term changes in visibility patterns between urban settlements are considered an important factor for understanding Iron Age II settlement locations in Southern Spain. From some settlements, the surrounding landscape and other settlements could be visually controlled, and some settlements are argued to be intervisible to allow for communication through visual signals. However, the study of how these visibility patterns changed in the subsequent Roman period in this region is largely ignored. In this paper, we argue that visibility might still have structured interactions between communities in Roman times and should not be dismissed out of hand merely because more and other data sources are available as compared to the Iron Age. However, the way in which it affected human behaviour might have been different in Roman times as compared to the Iron Age. We argue that simulating archaeologists’ hypotheses about the emergence of inter-settlement visibility is a promising way of understanding such differences. To do this, we use exponential random graph modelling (ERGM), a statistical network simulation modelling technique that allows us to simulate hypotheses about the emergence and long-term change of visibility networks. We combine this approach with an exploratory analysis of the observed visibility networks between identified urban settlements, which will reveal similarities and differences in the changing patterns of visibility networks through time. The results of the ERGMs are then compared with the changes in the observed network structure. We conclude that our knowledge of the changes from the Iron Age II to the Roman settlement pattern suggests only gradual changes in the role of visibility in structuring inter-settlement interactions, possibly followed by a disintegration of the visibility network after the Roman Early Imperial period.


Roman Spain Iberian archaeology ERGM Network analysis Visibility analysis 



The ‘Urban Connectivity in Iron Age and Roman Southern Spain’ project directed by Prof. Simon Keay and Dr. Graeme Earl was funded by the UK Arts and Humanities Research Council (AHRC) between 2002 and 2005 with subsequent support by the University of Southampton and institutions in Seville, notably the Departamento de Prehistoria I Arqueología de la Universidad de Sevilla and the Delegación de Cultura de la Junta de Andalucía. We would like to thank Cat Cooper for help with the maps, Leticia López Mondéjar for bibliographical suggestions, Matt Peeples for suggestions concerning sensitivity analyses, Iza Romanowska, Mari Carmen Moreno Escobar, Viviana Amati, two peer reviewers and the editors of this special issue for helpful comments on different versions of the manuscript, Pablo Garrido González for expert advice on the study area and Dave Wheatley for his ArcGIS Python script.

Supplementary material

10816_2014_9231_MOESM1_ESM.xls (276 kb)
ESM 1 (XLS 275 kb)


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Archaeological Computing Research GroupUniversity of SouthamptonSouthamptonUK
  2. 2.Department of Computer & Information ScienceUniversity of KonstanzKonstanzGermany

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