The Use of Network Cartography for Visualizing Large Prehistoric Relationships

Presentation held at session S08: "Are you my type? Network analysis and the study of material culture" at the Annual Conference of Computer Applications and Quantitative Methods in Archaeology (CAA) 2022, Oxford on 2022-08-09. 

The ever growing record of digital archaeology allows us to construct increasingly complex networks of ancient human relationships. However, the more extensive the networks are, the more difficult they become for humans to interpret. This is where cartographic methods from the field of big data can help.

The ROCEEH Out of Africa Database (ROAD) is one of the most comprehensive data collections containing archaeological, anthropological, paleontological, and environmental data with >15,000 assemblages from >2,100 sites with relevance to the physical and cultural evolution of hominins between 3,000,000 and 20,000 years ago. For this study, we queried a dataset representing the Middle Stone Age and Middle Paleolithic in Africa and Eurasia, respectively. The query includes localities, dating information, cultural categorization, and 32 further attributes, such as lithic tool groups, organic tools, symbolic behavior, personal ornaments, materials like ochre and egg shells, or the use of fire. Based on this data, we calculated the cultural similarity of temporally close assemblages and created a weighted network. In this network, assemblages whose age ranges overlap are represented by nodes, and cultural similarity is represented by weighted edges.

To represent the 3.5 million edges, we used a cartographic method related to flow maps, an idea which is used for the visualization of big data. A well-known example is Paul Butler's Facebook Friendship Map (2010), which shows the global spread of the social network and confirms this method as suitable for mapping centers and peripheries, natural and artificial boundaries, and connectivity and isolation. In contrast to classical cartographic methods of generalization and abstraction that tend to simplify representation, this variant allows patterns to emerge from the totality of the connections to illustrate the overall picture. This effect is the result of a minimalist design and a carefully calculated symbology that results from the weighting and length of the edges.

We present results for the cultural similarities within the Middle Stone Age and Middle Paleolithic separately as well as between them. As further examples, we show a selection of technocomplexes like the Acheulean, Mousterian, Aterian, Howiesons Poort and Initial Upper Paleolithic.  Furthermore, we discuss alternative ways to estimate cultural similarities and conceptualize temporal overlap. We also present ideas to further develop this approach, such as an interactive web app that allows researchers to adjust parameters and thus explore ancient cultural networks on their own.