New publication: sensitivity analysis in archaeological simulation

Read about the necessary but terrifying process of having our MERCURY model replicated. How robust were our previously published results? Hilde Kanters’ excellent work! With Iza Romanowska and myself.

Read the open access paper here https://www.sciencedirect.com/science/article/pii/S2352409X21001863

Jeroen Poblome and I published the MERCURY model in 2016 https://doi.org/10.15184/aqy.2016.35… We performed a selected set of experiments that allowed us to explore the model’s behaviour. But how robust were the results that we published there?

Our original experiments suggested that weak market integration (low availability of reliable non-local information), equal production capacities of pottery manufacturers, and equal demands at settlements throughout the roman world were unlikely to explain tableware distributions. We came to these conclusions by performing 34 experiments where we changed the relevant parameters of the MERCURY model that represented key explanatory factors. These experiment settings are shown in detail in our 2016 paper in JASSS: http://dx.doi.org/10.18564/jasss.2953

34 experiments is pretty good for an archaeological model, I tell myself. And certainly they suggest how the model behaves. But they do not reflect the full range of theoretically possible scenarios: we did not originally explore the full possible parameter space.

In comes the fantastic Hilde Kanters, who independently performed a replication of the MERCURY model in Repast Symphony (the original was coded in Netlogo) using only our publications. Her MSc thesis at Leiden University. Imagine my terror/excitement when I heard.

The replication study came to substantively the same conclusions as we did *massive sigh of relief* and made some very critical but constructive recommendations *massive collegial handshake*

This replication study is available open access https://studenttheses.universiteitleiden.nl/handle/1887/68248

The replication was made possible because not only did we publish the technical side of the model in detail in JASSS but mainly because we made the model code openly available on Comses OpenABM https://comses.net/codebases/4347/releases/1.1.0/

We were so impressed with Hilde Kanters’ work and delighted when the opportunity arose for her to do an internship in project MERCURY when I was at UBICS in Barcelona (such a great place to be as a complexity scientist). And Iza Romanowska luckily co-supervised this internship, which really set it up for excellent outputs. But what to do? I had loads of fun ideas to expand MERCURY: transport routes, equilibrium model, pots in spaaaaaaaaaice.

But in the end we knew we needed to do the responsible thing: check how robust the previously published results of MERCURY were by exploring the parameter space. We did a sensitivity analysis! See the results in our new paper in JASR. We now understand the model so much better, and I can be very confident of two key conclusions: the explanatory power of limited availability of reliable non-local information, and of strong differences in production capacity. But crucially, the sensitivity analysis also revealed I should be more cautious about the explanatory power of differences in demand throughout the Roman world: this was a new unexpected result, and will inform how I develop MERCURY in the future for sure.

Another thing that became painfully clear when working on this paper was the sad fact that ARCHAEOLOGISTS DON’T DO SENSITIVITY ANALYSES… But hey, we can help you on your way. We published a script for performing sensitivity analyses of ABM that can be reused by anyone, hurray! https://zenodo.org/record/4741208

Read more in the paper: https://www.sciencedirect.com/science/article/pii/S2352409X21001863

Abstract

Computational modelling is increasingly gaining attention in archaeology and related disciplines. With the number of new models growing it is often difficult to evaluate their significance and the generality of the results. This is partially due to the narrow reporting of the model’s results, which are often limited to those directly relevant to the research question posed in the first place. Although this is not an issue per se, models, if explored exhaustively, can provide a much wider perspective on the studied system. Sensitivity analysis is a widely recognised model exploration method for assessing the importance of different parameters on the model’s behaviour. Such systematic exploration helps in unravelling the dynamics that drive the model and enable researchers to establish how robust the presented results are. Here we present a sensitivity analysis of MERCURY, a previously published archaeological agent-based model. The results show that two out of three of the original conclusions drawn on the basis of selective experiment design stand up to scrutiny. By describing in detail and providing a reusable script with detailed description of all steps of the sensitivity analysis we hope to promote this important model exploration technique among modellers and the wider archaeological audience.

Our new publication in JAMT: over half a million pot sherds from Jerash and simulation

Really delighted to announce that our latest paper was recently published open access online in the Journal of Archaeological Method and Theory. It’s the result of years of collaborating between excavators, ceramics specialists and simulation experts. We analysed over half a million ceramics sherds from Jerash (ancient Gerasa, in Jordan), and identified that over 99% of the stuff was locally produced. What really excited me in this collaboration was the discrepancy between this proportion and the tendency for classical archaeologists (including myself) to always focus on imports.

Read the open access paper here.

The proportion of locally produced, regional and imported pottery for (left: ‘total’) all excavated ceramics (n = 625,063; excludes 133,584 topsoil entries), (middle) three securely dated trenches closed by the earthquake event of AD 749 (K n = 10 006; P n = 2184; V n = 10 614) and (right) three trenches consisting of ancient olive oil press installations filled in with ceramics (B n = 58 751; J n = 144 390; N n = 71 555)

Caption feature image: The Jerash Northwest Quarter excavations with trench letters (© Danish-German Jerash Northwest Quarter Project)

Why are there so many locally produced ceramics in Jerash, and so few regional and imported ones? This new publication quantitatively analyses the more than half a million sherds that were recorded by the Danish-German Jerash Northwest Quarter Project, and discusses different answers to this question. I applies innovative simulation techniques to evaluate whether personal preference for local Jerash products might have played a role. The result? The authors show that three ways of conceptualising preference for the local product might explain the ceramic data pattern, but other theories of preference are less good explanations.

Abstract

The Danish-German Jerash Northwest Quarter Project revealed a robust and striking pattern of the extreme dominance (>99%) of locally produced ceramics over six centuries and across different depositional contexts (in total over half a million pottery sherds). The archaeology of Jerash points towards an exceptional degree of self-sufficiency in craft products: why? The project team implemented a full quantification approach during excavation, manually and digitally recording and counting all pottery and other classes of artefacts. This enabled a full analysis of trends in production and use of ceramics throughout the archaeologically documented history of Jerash and revealed the unexpected pattern of the extreme dominance of local pottery. Archaeologists formulated a set of hypotheses to explain this pattern, and we developed an agent-based model of simple customer preference driving product distribution to evaluate several explanatory factors and their potential interactions. Our simulation results reveal that preference for locally produced ceramics at Jerash might be a plausible theory, but only if its intrinsic value was considered rather high in comparison to other goods, or if it was preferred by a majority of the population, and there was a tendency to follow this majority preference (or a combination of these factors). Here, we present a complete research pipeline of a full quantification of ceramics, analysis and modelling applicable at any archaeological site. We argue that transparent methods are necessary at all stages of an archaeological project: not only for data collection, management and analysis but also in theory development and testing. By focusing on a common archaeological material and by leveraging a range of widely available computational tools, we are able to better understand local and intra-regional distribution patterns of craft products in Jerash and in the ancient eastern Mediterranean.

Results of different simulation experimental setups. Each boxplot represents how close the simulated proportions of local, regional and imported ceramics are to the archaeologically observed ceramics (100 repetitions; 500 time steps; 100 agents)

Open Science in Archaeology: publication and special interest group

Work for two years, write a paper about it in two months, lose all rights to it in a second, hide it behind a pay-wall… Sound familiar? This is the traditional academic process in archaeology. Our very diverse work ranging from excavation, over lab tests, to interpretations is often only made available through a summarising publication that is rarely accessible to anyone other than institutions paying huge amounts of money. This is just not the way science works anymore. In such a system, how can we find out all the details of excavation results? How can we reproduce lab tests? How can we evaluate the empirical and historical background to a published interpretation in exhaustive detail? The answer is: we can’t.

It’s time for this traditional practice to change. Archaeology should follow the trend in academia towards more open science. The argument for open science in archaeology is made elaborately by Ben Marwick in a recently published paper in the SAA archaeological record, and the statements are supported by a large group of archaeologists (including myself). The paper announces the start of the SAA open science in archaeology special interest group. Check out the group’s wiki and get involved!

Here’s the paper’s abstract:

In archaeology, we are accustomed to investing great effort into collecting data from fieldwork, museum collections, and other sources, followed by detailed description, rigorous analysis, and in many cases ending with publication of our findings in short, highly concentrated reports or journal articles. Very often, these publications are all that is visible of this lengthy process, and even then, most of our journal articles are only accessible to scholars at institutions paying subscription fees to the journal publishers. While this traditional model of the archaeological research process has long been effective at generating new knowledge about our past, it is increasingly at odds with current norms of practice in other sciences. Often described as ‘open science’, these new norms include data stewardship instead of data ownership, transparency in the analysis process instead of secrecy, and public involvement instead of exclusion. While the concept of open science is not new in archaeology (e.g., see Lake 2012 and other papers in that volume), a less transparent model often prevails, unfortunately. We believe that there is much to be gained, both for individual researchers and for the discipline, from broader application of open science practices. In this article, we very briefly describe these practices and their benefits to researchers. We introduce the Society for American Archaeology’s Open Science Interest Group (OSIG) as a community to help archaeologists engage in and benefit from open science practices, and describe how it will facilitate the adoption of open science in archaeology.

Caribbean views: two new publications

My colleagues and friends doubt my professionalism when I show Caribbean views like this, taken whilst “working”. The last two years I’ve actually been working quite hard, but it’s just difficult to make Caribbean archaeology look like hard work. It was an absolute privilege to meet and learn from colleagues and friends in a number of Caribbean islands, about their knowledge of the landscapes that surround them and their relationship to the peoples who lived there before them. The current natural disasters befalling many of these islands, and their fall-out, are terrible. I wish all my friends there much strength and hope their respective governments (and aid workers around the world) do their duties in taking care of their residents.

Some of my work in Caribbean archaeology has now been published, and is available for free! (Download links: archaeological paper; methodological paper)

A first paper, co-authored with Maaike de Waal, Corinne Hofman and Ulrik Brandes, explores what we can learn about Amerindian social networks by examining Caribbean views: how places are connected based on what can be seen from them. It applies a wide range of computational methods (visibility networks, total viewsheds, visual neighbourhood configurations), but it should not be seen as a methodological exercise. The paper aimed to express some of the ideas that Caribbean archaeologists have formulated about how views could have mattered to past peoples, because they could be used for navigation, to share information through smoke or fire signalling, or to determine suitable settlement locations. Doing so led to some unique insights into the connectivity of landscapes in Eastern Guadeloupe (the paper’s research area), that led us to formulate a theory about the structuring role played by views in the pre-colonial Lesser Antilles as a whole: short-distance views at which people or smoke signals could be seen structured placement of settlements and community interactions locally, within regions on landmasses; whereas long-distance views at which only huge landmasses could be seen would structure navigation between communities on different landmasses. We see the Lesser Antilles as consisting of thousands of local connectivity  clusters, all connected through the long-distance visibility of landmasses (see figure below).

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The Eastern Guadeloupe study area, showing important long distance views connecting settlements (dotted lines) and clusters of short distance views between settlements (solid lines).

A second paper, co-authored with Ulrik Brandes, vastly expands the methodological toolbox for visibility network methods. Having reviewed the archaeological use of formal methods for studying visibility phenomena (i.e. what people in the past could see), we noticed that there was a discrepancy between the theories formulated and the methods used to explore them. The theories were often very complex, involving many different ways in which visibility could have structured past human behaviour and could have affected past human decision-making. Few of these theories have been explored using formal methods, often because of their share complexity, and those that have been treated formally were explored with a very limited range of formal methods: mainly binary viewsheds and simple visibility network representation. So we thought there was some fun methodological work to be done here, that could benefit future archaeological (and other) research. We approached visibility as a purely relational phenomenon, connecting the observer’s eyes with the observed feature. Doing so allowed us to represent any kind of visibility study to be represented as networks, which led to some really cool new network representation. For example (see figure below), a cumulative view shed can be represented as a two-mode network where observation points like site locations are connected to the landscape locations that can be observed from them. This two-network can be split up into two one-mode networks: a network where sites are connected if they have landscape locations in common that can be seen from both, and a network where landscape locations are connected if they have sites in common from which both can be observed. In addition, we also explored how complex theories of visibility can be teased apart into their constituent parts, where each part is represented by a small network data representation. We can count the frequency of these patterns and even simulate the preferential creation of these patterns, to explore how probable our complex theories are.

I will write more about these studies at a later time. All of this work was funded by EU HERA and ERC Synergy funding. Don’t hesitate to get in touch if you like this kind of thing!

Brughmans_Brandes_Fig3_NEW

The Connected Past special issue of Journal of Archaeological Method and Theory out now!

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I am super massively chuffed to announce that The Connected Past special issue of the Journal of Archaeological Method and theory is out now. It aims to provide examples of the critical and innovative use of network science in archaeology in order to inspire its more widespread use. What’s even better, the editorial is open access! And it’s accompanied by a glossary of network science techniques and concepts that we hope will prove to be a useful resource for archaeologists interested in network concepts.

My fellow editors Anna Collar, Fiona Coward, Barbara Mills and I are extremely grateful to all the authors of this special issue for their great contributions. You can read in the editorial the details of why we think these contributions are great. We would also like to thank the editors of Journal of Archaeological Method and Theory for offering us great support throughout the process, and to Springer for agreeing to make the editorial open access.

Original papers in this issue (Gotta read ’em all!):

Networks in Archaeology: Phenomena, Abstraction, Representation
by the editors Anna Collar, Fiona Coward, Tom Brughmans, and Barbara J. Mills

Are Social Networks Survival Networks? An Example from the Late Pre-Hispanic US Southwest
by Lewis Borck, Barbara J. Mills, Matthew A. Peeples, and Jeffery J. Clark

Understanding Inter-settlement Visibility in Iron Age and Roman Southern Spain with Exponential Random Graph Models for Visibility Networks
by Tom Brughmans, Simon Keay, and Graeme Earl

Inferring Ancestral Pueblo Social Networks from Simulation in the Central Mesa Verde
by Stefani A. Crabtree

Network Analysis of Archaeological Data from Hunter-Gatherers: Methodological Problems and Potential Solutions
by Erik Gjesfjeld

Procurement and Distribution of Pre-Hispanic Mesoamerican Obsidian 900 BC–AD 1520: a Social Network Analysis
by Mark Golitko, and Gary M. Feinman

The Equifinality of Archaeological Networks: an Agent-Based Exploratory Lab Approach
by Shawn Graham, and Scott Weingart

Remotely Local: Ego-networks of Late Pre-colonial (AD 1000–1450) Saba, North-eastern Caribbean
by Angus A. A. Mol, Menno L. P. Hoogland, and Corinne L. Hofman

The Diffusion of Fired Bricks in Hellenistic Europe: A Similarity Network Analysis
by Per Östborn, and Henrik Gerding

I got a top cited article! What does that mean?!?

Yesterday the Research Excellence Framework results were published, and it was therefore a nice coincidence to be notified by Springer yesterday that my paper is one of the top cited papers in Journal of Archaeological Method and Theory of 2013/2014. You can see it on this picture:

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I am really happy and grateful about this. However, it did make me wonder what it means in numbers to have a top cited article. The answer is rather sobering: not much! In this blog post I will have a little look around citation land, and share some take-home messages about citation and impact in archaeology with you. Read on until the end, and you might find a call for revolution in the academic publishing world! 🙂

The source mentioned is ISI/Thomson Reuters database, and luckily I can access their metrics through Web of Science. A quick search revealed this paper has 8 citations on Web of Science (all databases), see the figure below:

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That’s a sobering eyeopener! Especially considering one of these 8 citations is by a paper I wrote myself. This tells me quite a lot about the impact of the Journal of Archaeological Method and Theory, about the bit of archaeology that I am specialised in, and about that part of archaeologists’ citation behaviour represented by Web of Science.

Let’s start by that last one. Web of Science only indexes publications (mainly journals) with a long and consistent editorial board and publication history, focusing almost exclusively on English as the language of science. It defends this policy by stating the fact that the majority of all citations (about 60% or so) cite papers in a minority of journals (I believe about 20%, but don’t cite me on this). So there’s a clear tendency here to include high impact publications. Archaeology does not have many journals of high impact with a long tradition and a stable editorial history, whilst English is definitely NOT the only language of academic archaeology which is mainly due to the need to publish excavation reports in the local language. From my citation network analysis work I get the impression that less than half of all citations are included in Web of Science.

Why do I know that? Well let’s compare my 8 citation in Web of Science with how many this paper got according to Google Scholar:

jamt3So according to Google Scholar this paper was cited 16 times. Now Google Scholar does not care so much about the language or format of publication, so a much larger number of publications is indexed. But these citations also include those that are usually not included in any impact scores, such as citations mentioned on presentation slides or poster uploaded to the internet.

Take-home message number 1: check the citations to your paper on multiple citation databases before bragging about your impact (Web of Science, Google Scholar, Scopus).

What about the Journal of Archaeological Method and Theory? It is not the highest rated journal in archaeology, but I do think it’s up there in the top ten or so. But the top ten of what? Journals are usually ranked by their impact factor, which is the measure introduced by the Institute for Scientific Information using the data you can access through Web of Science. It represents the average number of citations in the last few years per paper in a journal. Here some Impact Factor results of the Journal of Archaeological Method and Theory:

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In 2013 ISI gave it an impact factor of 1.389 which ranked it 18th in Anthropology, just below Antiquity and just above American Antiquity. These rankings are published yearly by ISI as the Journal Citation Reports. But there are more measures than just the Impact Factor. Google Scholar uses the h5 index to rank journals in disciplines: “the h5 index is the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2009-2013 have at least h citations each”. In the category of Archaeology the Journal of Archaeological Method and Theory has an h5 index of 13 and ranks 15th: lower than American Antiquity and dwarfed by the scores of Journal of Archaeological Science (38) and Antiquity (21).

These measures of impact give you an idea of the number of citations on average a paper in a journal receives. This is not solely a result of a paper’s own merit or infamy. It should at least in part be seen as an effect of the journal itself being widely read, so papers published in well-known journals attract more citations because they adopt the visibility of the journal they are published in.

But citation practices differ greatly between disciplines. A quantitative measure of impact might therefore not be particularly relevant for all disciplines. For the humanities a more qualitative interpretation of impact is available: the European Reference Index for the Humanities. The site was down when I wrote this blog post, but the idea is simple. It gives a journal one of three ratings: of importance to a subdiscipline, of national importance for a discipline, of international importance for a discipline. But essentially this is just a low level classification based on a quantification of who publishes, cites, and reads each journal.

Take-home message number 2: impact is relative. Compare multiple measures as presented by multiple institutions. Visibility to your subdiscipline is more important than overall visibility/impact.

So my paper might not be cited by many, and it might not be published in the highest impact journal, but it is a piece of work I am pretty pleased with and it seems to reach the few people around the world who have the same niche interests I have. Having many citations according to ISI in my discipline really does not mean much. Way more impressive is the number of views and downloads this paper gets on sites like Academia.edu. We publish our work because we want to share it with those who are interested, and we want to provoke discussion with the final aim to advance human knowledge. Who cares about high citation counts? Just make sure your paper is out there, freely available, actively promote it, send it to those who might be interested in discussing it with you. That’s what you want, not a high impact factor. All these numbers, and especially the Research Excellence Framework, make us forget sometimes that it is science we are doing.

(PS: as a young academic I realize my own career will be enhanced by playing this numbers game. I am sure it will, for now. But I also think things are changing with resources like Academia.edu, which will hopefully push entities with empty prestige like Science and Nature off their pedestals. Scientific quality control is not guaranteed by prestigious publishers, and there are other models of publishing that allow us to debunk bullshit science and keep the good bits)

MANIFESTO! for the study of ancient Mediterranean maritime networks

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MANIFESTO! Somehow I feel like this word should always be written in capitals and accompanied by an exclamation mark. I feel the same about the word REVOLUTION! I recently co-authored a manifesto for the first time, but the feeling was less revolutionary than I thought it would be. In November 2013 I attended a meeting at the University of Toronto, hosted by Justin Leidwanger and Carl Knappett. The meeting aimed to discuss network approaches to the study of maritime connectivity in the ancient Mediterranean. It brought together a group of archaeologists, historians and physicists working either in the Mediterranean or experienced with network approaches to the study of the past. An edited volume collecting all papers presented at this meeting is being prepared. But the key findings of our discussions were recently published in Antiquity+ as ‘A manifesto for the study of ancient Mediterranean maritime networks‘.

The manifesto has a very clear focus on the past phenomena that fall under the rather generic term ‘maritime connectivity’. A useful but simplifying definition of this term would be: ways in which people, places, and things separated by water were related. The manifesto makes methodological and theoretical suggestions that can be assembled into a research framework that will allow us to better understand past maritime connectivity. It is important to stress again that connectivity and past networks are referred to and treated in the manifesto as past phenomena, as things that actually happened or existed in the past. Although the authors see potential for approaches that conceptualise and formalise past connectivity as network concepts and data, it is not our main aim to understand these concepts and data. We hope to better understand the past social phenomena we are interested in, and we argue that network methods and theories offer some potential to help us do so. Two quotes from the manifesto (which raise discussion points I am particularly passionate about) should suffice to illustrate this focus: “formulating explicitly social questions should necessarily precede examination of spatial networks” and there is a “need to review critically our assumptions concerning the social function of maritime connectivity and the actors involved in these networks”.

The manifesto concludes by stressing the virtue of multi-vocality: there is no need for a single homogeneous maritime network studies approach. I believe this is a cautious and constructive attitude, in particular in light of the novelty of applying network methods and theories in our disciplines. We really have not yet discovered the full potential of these approaches for our disciplines. Until we have, we need to think and do creatively! And most importantly, evaluate critically and constructively! MANIFESTO!

The full manifesto is available for free on the Antiquity website.

In this oneoff, extended Project Gallery article, the participants of a recent workshop jointly present a manifesto for the study of ancient Mediterranean maritime connectivity. Reviewing the advantages and perils of network modelling, they advance conceptual and methodological frameworks for the productive study of seaborne connectivity. They show how progressive research methods can overcome some of the problems encountered when working with uneven datasets spanning large geographical regions and long periods of time. The manifesto suggests research directions that could better inform our interpretations of human connections, both within and beyond the Mediterranean. All references to the authors’ workshop papers in the text denote their oral presentations at the ‘Networks of Maritime Connectivity in the Ancient Mediterranean’ workshop held at the University of Toronto in November 2013.

The networks they are a-changin’: introducing ERGM for visibility networks

legosIn my madness series of posts published a few months ago I mentioned I was looking for a method to study processes of emerging intervisibilty patterns. I can finally reveal this fancy new approach to you 🙂 Here it is: introducing exponential random graph modelling (ERGM) for visibility networks. In previous posts I showed that when archaeologists formulate assumptions about how lines of sight affected past human behaviour, these assumptions imply a sequence of events rather than a static state. Therefore, a method is needed that allows one to test these assumed processes. Just analysing the structure of static visibility networks is not enough, we need a method that can tackle changing networks. ERGM does the trick! I just published a paper in Journal of Archaeological Science with Simon Keay and Graeme Earl that sets out the archaeological use of the method in detail. You can download the full paper on ScienceDirect, my Academia page or via my bibliography page. But in this blog post I prefer to explain the method with LEGOs 🙂

 

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Social network analysts often use an archaeological analogy to explain the concept of an ERGM (e.g., Lusher and Robins 2013, p. 18). Past material remains are like static snapshots of dynamic processes in the past. Archaeologists explore the structure of these material residues to understand past dynamic processes. Such snapshots made up of archaeological traces are like static fragmentary cross-sections of a social process taken at a given moment. If one were to observe multiple cross-sections in sequence, changes in the structure of these fragmentary snapshots would become clear. This is exactly what an ERGM aims to do: to explore hypothetical processes that could give rise to observed network structure through the dynamic emergence of small network fragments or subnetworks (called configurations). These configurations can be considered the building blocks of networks; indeed, LEGO blocks offer a good analogy for explaining ERGMs. To give an example, a network’s topology can be compared to a LEGO castle boxed set, where a list of particular building blocks can be used to re-assemble a castle. But a LEGO castle boxed set does not assemble itself through a random process. Instead, a step by step guide needs to be followed, detailing how each block should be placed on top of the other in what order. By doing this we make certain assumptions about building blocks and their relationship to each other. We assume that in order to achieve structural integrity in our LEGO castle, a certain configuration of blocks needs to appear, and in order to make it look like a castle other configurations will preferentially appear creating ramparts, turrets, etc. ERGMs are similar: they are models that represent our assumptions of how certain network configurations affect each other, of how the presence of some ties will bring about the creation or the demise of others. This is where the real strength of ERGMs lies: the formulation and testing of assumptions about what a connection between a pair of nodes means and how it affects the evolution of the network, explicitly addressing the dynamic nature of our archaeological assumptions.

More formally, exponential random graph models are a family of statistical models originally developed for social networks (Anderson et al. 1999; Wasserman and Pattison 1996) that aim to scrutinize the dependence assumptions underpinning hypotheses of network formation by comparing the frequency of particular configurations in observed networks with their frequency in stochastic models.

The figure below is a simplified representation of the creation process of an ERGM. (1a) an empirically observed network is considered; (1b) in a simulation we assume that every arc between every pair of nodes can be either present or absent; (2) dependence assumptions are formulated about how ties emerge relative to each other (e.g. the importance of inter-visibility for communication); (3) configurations or network building blocks are selected that best represent the dependence assumptions (e.g. reciprocity and 2-path); (4) different types of models are created (e.g. a model without dependence assumptions (Bernoulli random graph model) and one with the previously selected configurations) and the frequency of all configurations in the graphs simulated by these models is determined; (5) the number of configurations in the graphs simulated by the models are compared with those in the observed network and interpreted.

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My madness series of posts and the recently published paper introduce a case study that illustrates this method. Iron Age sites in southern Spain are often located on hilltops, terraces or at the edges of plateaux, and at some of these sites there is evidence of defensive architecture. These combinations of features may indicate that settlement locations were purposefully selected for their defendable nature and the ability to visually control the surrounding landscape, or even for their inter-visibility with other urban settlements. Yet to state that these patterns might have been intentionally created, implies a sequential creation of lines of sight aimed at allowing for inter-visibility and visual control. An ERGM was created that simulates these hypotheses. The results suggest that the intentional establishment of a signalling network is unlikely, but that the purposeful creation of visually controlling settlements is better supported.

A more elaborate archaeological discussion of this case study will be published very soon in Journal of Archaeological Method and Theory, so stay tuned 🙂 Don’t hesitate to try out ERGMs for your own hypotheses, and get in touch if you are interested in this. I am really curious to see other archaeological applications of this method.

References mentioned:

Anderson, C. J., Wasserman, S., & Crouch, B. (1999). A p* primer: logit models for social networks. Social Networks, 21(1), 37–66. doi:10.1016/S0378-8733(98)00012-4

Lusher, D., Koskinen, J., & Robins, G. (2013). Exponential Random Graph Models for Social Networks. Cambridge: Cambridge university press.

Lusher, D., & Robins, G. (2013). Formation of social network structure. In D. Lusher, J. Koskinen, & G. Robins (Eds.), Exponential Random Graph Models for Social Networks (pp. 16–28). Cambridge: Cambridge University Press.

Wasserman, S., & Pattison, P. (1996). Logit models and logistic regressions for social networks: I. An introduction to Markov graphs and p*. Psychometrika, 61(3), 401–425.

First Connected Past publication!

coverphotoAnna Collar, Fiona Coward and I started The Connected Past in 2011. Since then we have been enjoying organising a number of conferences, workshops and sessions together with our many friends in the TCP steering committee. Many collaborations and other fun things have followed on from these events but no publications yet, until now! Anna, Fiona, Claire and I recently published a paper in Nouvelles de l’archéologie. It was part of a special issue on network perspectives in archaeology edited by Carl Knappett.

Our paper’s aims are very similar to those of TCP in general: to communicate across communities of archaeologists and historians, to identify the challenges we face when using network perspectives, and to overcome them together. The paper first lists a number of challenges historians are confronted with, then a number of archaeological challenges. It argues how some of these challenges are similar and that it’s worth our while to collaborate. At the end of the paper we suggest a few ways of doing this. And it will be no surprise that one of the ways is to attend our future TCP events 🙂

You can download the full paper on Academia or via my bibliography page. You can read the abstract below.

The Connected Past will also publish a special issue of the Journal of Archaeological Method and Theory (first issue of 2015) and an edited volume (Oxford University Press, 2015). More about that later!

The last decade has seen a significant increase in the use of network studies in archaeology, as archaeologists have turned to formal network methods to make sense of large and complex datasets and to explore hypotheses of past interactions. A similar pattern can be seen in history and related disciplines, where work has focused on exploring the structure of textual sources and analysing historically attested social networks. Despite this shared interest in network approaches and their common general goal (to understand human behaviour in the past), there has been little cross-fertilisation of archaeological and historical network approaches. The Connected Past, a multidisciplinary conference held in Southampton in March 2012, provided a rare platform for such cross-disciplinary communication. This article will discuss the shared concerns of and seemingly unique challenges facing archaeologists and historians using network analysis techniques, and will suggest new ways in which research in both disciplines can be enhanced by drawing on the experiences of different research traditions.

The conference brought some common themes and shared concerns to the fore. Most prominent among these are possible methods for dealing with the fragmentary nature of our sources, techniques for visualising and analysing past networks – especially when they include both spatial and temporal dimensions – and interpretation of network analysis results in order to enhance our understanding of past social interactions. This multi-disciplinary discussion also raised some fundamental differences between disciplines: in archaeology, individuals are typically identified indirectly through the material remains they leave behind, providing an insight into long-term changes in the everyday lives of past peoples; in contrast, historical sources often allow the identification of past individuals by name and role, allowing synchronic analysis of social networks at a particular moment in time.

The conference also demonstrated clearly that a major concern for advancing the use of network analysis in both the archaeological and historical disciplines will be the consideration of how to translate sociological concepts that have been created to deal with interaction between people when the nodes in our networks are in fact words, texts, places or artefacts. Means of textual and material critique will thus be central to future work in this field.

Problems with archaeological networks part 3

spagThis third blog post in the series discusses space-related issues in archaeological network studies. As I mentioned before, I recently published a review of formal network methods in archaeology in Archaeological Review from Cambridge. I want to share the key problems I raise in this review here on my blog, because in many ways they are the outcomes of working with networks as an archaeologist the last six years. And yes, I encountered more problems than I was able to solve, which is a good thing because I do not want to be bored the next few years 🙂 In a series of four blog posts I draw on this review to introduce four groups of problems that archaeologists are faced with when using networks: method, data, space, and process. The full paper can be found on Academia.

The definition of nodes is not only dependent on data type categorisation but also necessarily reflects the research questions being asked, revealing an issue of spatial scales. Do the past processes we are interested in concern interactions between regions, sites or individuals? How will this be represented in node, tie and network definitions? The ability of network approaches to work on multiple scales is often mentioned as one of the advantages of using formal network methods (Knappett 2011). In practice, however, archaeological network analysts have traditionally focused on inter-regional or macro-scales of analysis. Knappett (2011) argues that it is on the macro-scale that network analysis comes into its own and a recently published edited volume reveals this regional emphasis (Knappett 2013). This insistence to work on large scales becomes quite unique in light of social network analysts’ traditional focus on individual social entities in interaction. SNA provides a multitude of good examples of how network methods could be usefully applied on a micro- or local scale of analysis (e.g. ego-networks). However, the nature of archaeological data, which rarely allows for individuals and their interactions to be identified with any certainty, should not be considered the only reason for this focus on the macro-scale. Arguably, networks lend themselves very well to exploring inter-regional interaction, and archaeologists have always had a particular interest in the movements and flows of people, resources and information across large areas. Moreover, many of the early applications of network methods in archaeology, which in some cases might have served as an example to more recent applications, concerned inter-regional interaction (e.g. Terrell 1976). One should acknowledge the importance of exploring how local actions give rise to larger-scale patterns if we are to benefit from the multi-scalar advantage of formal network methods (Knappett 2011).

It is not surprising that many archaeological network analysts are interested in exploring the dynamics between relational and geographical space (e.g. Bevan and Wilson 2013; Knappett et al. 2008; Menze and Ur 2012; Wernke 2012), given the importance of spatial factors in understanding archaeological data and archaeologists’ traditional interest in geographical methods (e.g. Hodder and Orton 1976). Despite early work by archaeologists on geographical networks (for an overview see chapter 2 in Knappett 2011), geographical space has been almost completely ignored by sociologists and physicists, resulting in a very limited geographical network analysis toolset for archaeologists to draw on (although see a recent special issue of the journal Social Networks [issue 34(1), 2012] and the review work by Barthélemy [2011], as well as techniques used in Space Syntax [Hillier and Hanson, 1984]).

References
Barthélemy, M. (2011). Spatial networks. Physics Reports, 499(1-3), 1–101. doi:10.1016/j.physrep.2010.11.002
Bevan, A., & Wilson, A. (2013). Models of settlement hierarchy based on partial evidence. Journal of Archaeological Science, 40(5), 2415–2427.
Hillier, B., & Hanson, J. (1984). The social logic of space. Cambridge: Cambridge University Press.
Hodder, I., & Orton, C. (1976). Spatial analysis in archaeology. Cambridge: Cambridge University Press.
Knappett, C. (2011). An archaeology of interaction: network perspectives on material culture and society. Oxford: Oxford University Press.
Knappett, C. (2013). Introduction: why networks? In C. Knappett (Ed.), Network analysis in archaeology. New approaches to regional interaction (pp. 3–16). Oxford: Oxford University Press.
Knappett, C., Evans, T., & Rivers, R. (2008). Modelling maritime interaction in the Aegean Bronze Age. Antiquity, 82(318), 1009–1024.
Menze, B. H., & Ur, J. a. (2012). Mapping patterns of long-term settlement in Northern Mesopotamia at a large scale. Proceedings of the National Academy of Sciences of the United States of America, 109(14), E778–87. doi:10.1073/pnas.1115472109
Terrell, J. E. (1976). Island biogeography and man in Melanesia. Archaeology and physical anthropology in Oceania, 11(1), 1–17.
Wernke, S. a. (2012). Spatial network analysis of a terminal prehispanic and early colonial settlement in highland Peru. Journal of Archaeological Science, 39(4), 1111–1122. doi:10.1016/j.jas.2011.12.014

Problems with archaeological networks part 2

Cuddly_Flying_Spaghetti_MonsterThis second blog post in the series discusses data-related issues in archaeological network studies. As I mentioned before, I recently published a review of formal network methods in archaeology in Archaeological Review from Cambridge. I want to share the key problems I raise in this review here on my blog, because in many ways they are the outcomes of working with networks as an archaeologist the last six years. And yes, I encountered more problems than I was able to solve, which is a good thing because I do not want to be bored the next few years 🙂 In a series of four blog posts I draw on this review to introduce four groups of problems that archaeologists are faced with when using networks: method, data, space, and process. The full paper can be found on Academia.

Network analysis is by no means a method devoid of any theoretical considerations. Most interestingly, theoretical critiques are often triggered by issues concerning the role of archaeological data. This is usually a result of the material nature of archaeological data serving as proxy evidence for past human behaviour, which poses a number of challenges.

Firstly, imposing categories and sometimes hierarchical relationships on data is a prerequisite for any network analysis. This results in the assumption that categories can actually be defined with any certainty (Butts 2009), and from the need to establish data categories ahead of the analysis, rather than letting them emerge from the analysis (Isaksen 2013). Indeed, the definition of nodes, ties and the network as a whole can be considered the most crucial phase of any archaeological network analysis. However straightforward such definitions seem, doing so in a critical manner is not as easy as it sounds. For example, we could choose to follow a formal ceramic typology, where each node represents a distinct type. When doing so we have to acknowledge that such typologies are modern constructs and that alternative categorisations can easily be developed. This in turn raises the issue that the network we analyse is not necessarily identical to the past networks we are trying to understand. For example, although in some cases it can be proven that particular ceramic types were used for particular purposes and in certain contexts, their meaning can nevertheless change through time, requiring a modification of our categorisation (van Oyen in press).

Secondly, unlike network analysts in many other disciplines, archaeologists work with primary data sources of a material nature. Social network analysts often only consider inter-personal interactions, whilst archaeological network analysts are forced to consider object-person and object-object interactions. A range of interactionist theoretical perspectives exist to confront materiality, and archaeological network analysts are faced with finding a workable framework that combines both network theories and methods (Knappett 2011).

In summary, the decisions archaeological network analysts make when defining nodes and edges, when selecting or modifying analytical techniques and when interpreting the outcomes, are fundamentally influenced by their theoretical preconceptions. There is not a single right way to incorporate and interpret archaeological data in network approaches.

References:
Butts, C. T. (2009). Revisiting the foundations of network analysis. Science, 325(5939), 414–6. doi:10.1126/science.1171022
Isaksen, L. (2013). “O What A Tangled Web We Weave” – Towards a Practice That Does Not Deceive. In C. Knappett (Ed.), Network analysis in archaeology. New approaches to regional interaction (pp. 43–70). Oxford: Oxford University Press.
Knappett, C. (2011). An archaeology of interaction. Network perspectives on material culture and society. Oxford – New York: Oxford University Press.
Oyen, A. Van. (n.d.). Networks or work-nets? Actor-Network Theory and multiple social topologies in the production of Roman terra sigillata. In T. Brughmans, A. Collar, & F. Coward (Eds.), The Connected Past: challenging networks in archaeology and history. Oxford: Oxford Univeristy Press.

Problems with archaeological networks part 1

Plate_of_SpaghettiAs I mentioned before, I recently published a review of formal network methods in archaeology in Archaeological Review from Cambridge. I want to share the key problems I raise in this review here on my blog, because in many ways they are the outcomes of working with networks as an archaeologist the last six years. And yes, I encountered more problems than I was able to solve, which is a good thing because I do not want to be bored the next few years 🙂 In a series of four blog posts I draw on this review to introduce four groups of problems that archaeologists are faced with when using networks: method, data, space process. The full paper can be found on Academia. This first blog post in the series discusses methodological issues, enjoy 🙂

Like any other formal techniques in the archaeologist’s toolbox (e.g. GIS, radiocarbon dating, statistics), formal network techniques are methodological tools that work according to a set of known rules (the algorithms underlying them). These allow the analyst to answer certain questions (the network structural results of the algorithms), and have clear limitations (what the algorithms are not designed to answer). This means that their formal use is fundamentally limited by what they are designed to do, and that they can only be critically applied in an archaeological context when serving this particular purpose. In most cases, however, these formal network results are not the aim of one’s research; archaeologists do not use network methods just because they can. Instead one thinks through a networks perspective about the past interactions and systems one is actually interested in. This reveals an epistemological issue that all archaeological tools struggle with: there is a danger that formal networks are equated with the past networks we are trying to understand (Isaksen 2013; Knox et al. 2006; Riles 2001). In other cases, however, formal analysis is avoided altogether and concepts adopted from formal network methods are used to describe hypothetical past structures or processes (e.g. Malkin 2011). Although this sort of network thinking can lead to innovative hypotheses, it is not formal network analysis (see reviews of Malkin (2011) by Ruffini (2012) and Brughmans (2013)). However, such concepts adopted from formal network methods often have a very specific meaning to network analysts and are associated with data requirements in order to express them. Most crucially, when the concepts one uses to explain a hypothesis cannot be demonstrated through data (not even hypothetically through simulation), there is a real danger that these concepts become devalued since they are not more probable than any other hypotheses. Moreover, the interpretation of past social systems runs the risk of becoming mechanised when researchers adopt the typical interpretation of network concepts from the SNA or physics literature without validating their use with archaeological data or without modifying their interpretation to a particular archaeological research context. This criticism is addressed at the adoption of formal network concepts only. It should be clear that other theoretical concepts could well use a similar vocabulary whilst not sharing the same purpose or data requirements, in which case I would argue to refrain from using the same word to refer to different concepts or explicitly address the difference between these concepts in order to avoid confusion.

Although it is easy to claim that the rules underlying formal network techniques are known, it is less straightforward to assume that the traditional education of archaeologists allows them to decipher these algorithms. Archaeologists are not always sufficiently equipped to critique the mathematical underpinnings of network techniques, let alone to develop novel techniques tailor-made to address an archaeological question. For many archaeologists this means a real barrier or at least a very steep learning curve. Sadly, it also does not suffice to focus one’s efforts on the most common techniques or on learning graph theory. Like GIS, network analysis is not a single homogeneous method: it incorporates every formal technique that visualises or analyses the interactions between nodes (either hypothetical or observed), and it is only the particular nature of the network as a data type that holds these techniques together (Brandes et al. 2013). For this purpose it draws on graph theory, statistical and probability theory, algebraic models, but also agent-based modelling and GIS.

A thorough understanding of the technical underpinnings of particular network techniques is not an option; it is a prerequisite for a critical interpretation of the results. A good example of this is network visualisation. Many archaeologists consider the visualisation of networks as graphs a useful exploratory technique to understand the nature of their data, in particular when combined with geographical visualisations (e.g. Golitko et al. 2012). However, there are many different graph layout algorithms, and all of them are designed for a particular purpose: to communicate a certain structural feature most efficiently (Conway 2012; Freeman 2005). These days, user-friendly network analysis software is freely available and most of it includes a limited set of layouts, often not offering the option of modifying the impact of variables in the layout algorithms. Not understanding the underlying ‘graph drawing aesthetics’ or limiting one’s exploration to a single layout will result in routinized interpretations focusing on a limited set of the network’s structural features.

Archaeologists who consider the application of network methods to achieve their research aims must be able to identify and evaluate such issues. Multi-disciplinary engagement or even collaboration significantly aids this evaluation process.

References:
Brandes, U., Robins, G., McCranie, A., & Wasserman, S. (2013). What is network science? Network Science, 1(01), 1–15. doi:10.1017/nws.2013.2
Brughmans, T. (2013). Review of I. Malkin 2011. A Small Greek World. Networks in the Ancient Mediterranean. The Classical Review, 63(01), 146–148. doi:10.1017/S0009840X12002776
Conway, S. (2012). A Cautionary Note on Data Inputs and Visual Outputs in Social Network Analysis. British Journal of Management. doi:10.1111/j.1467-8551.2012.00835.x
Freeman, L. C. (2005). Graphic techniques for exploring social network data. In P. J. Carrington, J. Scott, & S. Wasserman (Eds.), Models and methods in social network analysis (Vol. 5, pp. 248–268). Cambridge: Cambridge University Press. doi:10.3917/enje.005.0059
Golitko, M., Meierhoff, J., Feinman, G. M., & Williams, P. R. (2012). Complexities of collapse : the evidence of Maya obsidian as revealed by social network graphical analysis. Antiquity, 86, 507–523.
Isaksen, L. (2013). “O What A Tangled Web We Weave” – Towards a Practice That Does Not Deceive. In C. Knappett (Ed.), Network analysis in archaeology. New approaches to regional interaction (pp. 43–70). Oxford: Oxford University Press.
Knox, H., Savage, M., & Harvey, P. (2006). Social networks and the study of relations: networks as method, metaphor and form. Economy and Society, 35(1), 113–140. doi:10.1080/03085140500465899
Malkin, I. (2011). A small Greek world: networks in the Ancient Mediterranean. Oxford – New York: Oxford University Press.
Riles, A. (2001). The Network inside Out. Ann Arbor, MI: University of Michigan Press.
Ruffini, G. (2012). Review of Malkin, I. 2011 A Small Greek World: Networks in the Ancient Mediterranean. American Historical Review, 1643–1644.

Special networky issue Archaeological Review Cambridge

arcNetworks are so hot right now in archaeology! I know of three archaeological journals publishing special issues on the topic very soon (will reveal this to you in later posts). Archaeological Review of Cambridge is the first of these to appear with a special issue titled ‘Social Network Perspectives in Archaeology’, edited by Kathrin Felder and Sarah Evans. The issue includes an editorial, a number of interesting papers, a reflective piece by Carl Knappett and some book reviews. I also published a paper in it titled ‘The roots and shoots of archaeological network analysis: A citation analysis and review of the archaeological use of formal network methods’. I will be introducing some pieces of this paper in future posts. For now, here is the contents of the special issue:

Social Network Perspectives in Archaeology
Issue 29.1, April 2014

Theme Editors: Sarah Evans and Kathrin Felder

Introduction
Making the connection: Changing perspectives on social networks
Sarah Evans and Kathrin Felder

The roots and shoots of archaeological network analysis: A citation analysis and review of the archaeological use of formal network methods
Tom Brughmans

Population genetics and the investigation of past human interactions
Hayley Dunn

Eruptions and ruptures — a social network perspective on vulnerability and impact of the Laacher See eruption (c. 13,000 BP) on Late Glacial hunter-gatherers in northern Europe
Felix Riede

Expanding social networks through ritual deposition: A case study from the Lower Mississippi Valley
Erin Nelson and Megan Kassabaum

‘Extending the self ’ through material culture: Private letters and personal relationships in second-century AD Egypt
Jo Stoner

Play-things and the origins of online networks: Virtual material culture in multiplayer games
Angus Mol

Reflection
The network approach: Tool or paradigm?
Francesca Fulminante

Commentary
What are social network perspectives in archaeology?
Carl Knappett

Book Reviews
Edited by Mat Dalton

Computational Approaches to Archaeological Spaces
Edited by Andrew Bevan and Mark Lake Beaudry and Travis G. Parno
Reviewed by Peter Alfano

Cities and the Shaping of Memory in the Ancient Near East
By Ömür Harmanşah
Reviewed by Georgia Marina Andreou

The Oxford Handbook of the Archaeology of Death and Burial
Edited by Sarah Tarlow and Liv Nilsson Stutz
Reviewed by Michaela Binder

Network Analysis in Archaeology: New Approaches to Regional Interaction
Edited by Carl Knappett
Reviewed by Beatrijs G. de Groot

The Origins and Spread of Domestic Animals in Southwest Asia and Europe
Edited by Sue Colledge, James Connolly, Keith Dobney, Katie Manning and Stephen Shennan
Reviewed by Sarah Elliott

The Archaeology of Kinship
By Bradley E. Ensor
Reviewed by Philipp Y. Kao

Matters of Scale: Processes and Courses of Events in the Past and the Present
Edited by Nanouschka M. Burström and Fredrik Fahlander
Reviewed by Hannah L. McBeth

Cultural Heritage and the Challenge of Sustainability
By Diane Barthel-Bouchier
Reviewed by Belinda C. Mollard

The 48th IIPP Annual Conference on the Veneto Region, held in Padua on 5–9 November 2013
Reviewed by Elisa Perego

Humans and the Environment: New Archaeological Perspectives for the Twenty-first Century
Edited by Matthew I.J. Davies and Freda Nkirote M’Mbogori
Reviewed by Rachel Swallow

Citation analysis paper published in LLC

llc262coverIt took a while, but it’s finally published! My citation network analysis of archaeological literature can now be found in Literary and Linguistic Computing, the Digital Humanities journal. The paper looks at how archaeologists that used formal network techniques cited each other, and it tries to trace where they got their ideas from. To do this I use citation network analysis techniques developed in a field called Bibliometrics. It doesn’t sound particularly sexy, but I think it’s pretty cool stuff. Academic papers have long lists of references they cite, which can be considered a formal expression of where they  got their ideas from, or what they were influenced by. Each one of those papers can be considered a point or node in a network. An arrow is drawn between two papers if one cites the other. This creates a pretty web of citations when done for 10 papers, but it creates a complex messy spaghetti monster when done for more than 30,000 papers, as I illustrate in my paper. So for this reason we use network techniques to tackle such massive datasets and say something interesting about them.

Over the coming weeks I will write blog posts about some of the more interesting findings of this work. But do have a look at the published paper. If you have access to LLC then download it here. If not then you can find a link on my bibliography page or you can download it on Scribd.

Special issue Journal of Archaeological Method and Theory: The Connected Past

TCPThis is a quick reminder of the 23rd June deadline for extended abstracts for The Connected Past special issue of the Journal of Archaeological Method and Theory. The call for submissions to this special issue is now open. So don’t hesitate any longer and send us that awesome networky paper you have been working on! As you can gather from the CFP below, we want to have a focused special issue with solid case studies that illustrate how network analysis can be useful in archaeology. However, we are really keen to publish really innovative approaches, things that have not been tried before by archaeological network analysts. We look forward to reading your abstracts!

CALL FOR PAPERS

The Connected Past: critical and innovative approaches to networks in archaeology

A special issue of Journal of Archaeological Method and Theory

Edited by: Anna Collar, Tom Brughmans, Fiona Coward and Barbara Mills

Over the last decade the number of published archaeological applications of network methods and theories has increased significantly. A number of research themes deserve further exploration, however. How do particular archaeological research contexts drive the selection and adaptation of formal network methods from the wide range of existing approaches? What is the role archaeological data can play in network methods? What are the decisions we are faced with when defining nodes and ties, and what assumptions underlie these definitions? How can our theoretical approaches be expressed through formal methods incorporating empirical data? Are network theories and methods compatible? How can materiality be incorporated within existing network approaches? How can we deal with long-term network evolution within archaeological research contexts?

This special issue aims to illustrate through innovative and critical archaeological case studies that these problems can be overcome, and that by doing so the role of archaeological network analysis within the archaeologist’s toolbox will become better defined.

This special issue invites well-developed archaeological case studies in which a network-based method is formulated as the best approach to an archaeological research question. A key conviction of this special issue is that theoretical and methodological concerns should be raised through practice. As such, papers are expected to either develop a critical and detailed archaeological analysis through commonly applied network-based approaches, or to illustrate how archaeological research contexts can require the development or adoption of innovative network techniques. Such a collection of case studies will illustrate that the network is not an end-product; it is a research perspective that allows one to ask and answer unique questions of archaeological relevance.

Please send extended abstracts (1000 words) to connectedpast@soton.ac.uk by 23 June 2013.

Notification of acceptance: July 2013.

Submission of full papers for peer-review to guest editors: 22 September 2013.

Submission of revised papers for peer-review to JAMT: 24 November 2013.

Please note that the acceptance of extended abstracts and peer-review by guest editors is not a guarantee that the paper will be published in the special issue. Individual papers will have to successfully go through the JAMT peer-review process before publication can be guaranteed.

Review of Malkin’s A Small Greek World published

9780199734818_450The end of 2011 for me was marked by the publication of two new networky books. The first one was Knappett’s An Archaeology of Interaction, which I reviewed for Antiquity (and I wrote a more in-depth review on this blog). The second one was Irad Malkin’s A Small Greek World, my review of which finally appeared in the journal Classical Review. You can access it on the journal’s website, download it from my bibliography page or read it here.

IRAD MALKIN. A small Greek world. Networks in the ancient Mediterranean. xix+251 pages, 18 illustrations. 2011. Oxford: Oxford University Press; 978-0-19-973481-8 hardback $60.

History books too often read like a series of unconnected events, dates, places and people, the sum of which is considered the historical narrative. In ‘A Small Greek World’ Irad Malkin does the exact opposite by focusing on the ties that bind and give meaning to historically attested entities. The reader is taken on a guided tour through the web of countless historical relationships between people, places and cultural practices in the Archaic Mediterranean and Black Sea. One is invited to explore this “Greek Wide Web” as a set of nodes and links to appreciate its small-world network structure and how long-distance links were instrumental to the emergence of “Greek civilization as we know it” (p. 5). At least, this is the hypothesis Malkin advocates in his latest book.

The introductory chapter sets out Malkin’s network perspective, which forms the book’s main innovative contribution to the study of ancient history (mainly due to an adoption of concepts from physics), which is why this review will be largely concerned with evaluating this aspect of the book. Malkin adopted the concept of small-world networks from two physicists, Duncan Watts and Steven Strogatz, who use the term to refer to a range of networks with a high degree of local clustering and a low average shortest path length. This means that although nodes are largely only connected to nodes within their cluster, every so often a link appears that bridges the gap between clusters and facilitates the flow of material or immaterial resources between clusters. Malkin was also influenced by two other physicists, Albert-László Barabási and Réka Albert, who coined the term scale-free networks for networks that exhibit a power-law distribution in the number of their nodes’ links. For the creation of this type of network structure, Barabási and Albert suggested a process of preferential attachment in which nodes are continually added to the network and preferentially create links with nodes that are already well connected, thus giving rise to super-connected hubs. In this book Malkin argues that during the Archaic period people and places around the Mediterranean and Black Sea were connected in a way that resembled a small-world structure, driven by processes of preferential attachment. Malkin stresses throughout the book that it was the long-distance links and decentralization of the small Greek world that facilitated the emergence of what he calls Greek civilization.

These network ideas are not expressed and validated in a quantitative manner, however, since historians of antiquity are considered not to possess enough data to identify such patterns and processes with any statistical significance (pp. 19, 25). Instead, Malkin takes a qualitative approach by adopting the vocabulary of network science, and the key features of small-world and scale-free network models in particular, and applies it to a series of historical examples in chapters two to six. Regardless of this, Malkin does consider his qualitative network perspective more than a mere description of the historical Greek network and stresses the explanatory value of his approach. The aims of the book are therefore twofold: to point out networks and processes of network formation through numerous examples, and the interpretation of the implications of describing structures and processes using a formal network vocabulary.

Chapters two and three illustrate reverse processes of the emergence of identity (as identified by Malkin through abstract as well as concrete historical examples) through networks. In chapter two the Rhodians’ dispersal overseas is seen as the reason for the consolidation of the island identity of Rhodes. Chapter three turns this process on its head by arguing for the emergence of the Sikeliôtai identity of Greeks from all over converging in Sicily. The altar of Apollo Archêgetês, only accessible to the Greek residents of Sicily, is considered the earliest expression of this ‘Greeks away from home’ identity. Chapter four brings Herakles the Greek and Melqart the Phoenician to the stage as examples of the existence of mythical and cultic networks, facilitating coexistence and peaceful mediation as well as justifying antagonism between ethnic groups. Malkin continues his series of example networks by focusing on the Phokaian network in the western Mediterranean in chapters five and six. Most interestingly, the evolution of this network is seen as changing from a many-to-many structure to one consisting of local clusters dominated by hubs with long-distance links, giving the example of Massalia and the coastal zone in southern France (described as a middle ground). In chapter six Malkin explores the similarities in cults (Artemis of Ephesos) and institutions (nomima) of the Phokaian network, which are considered to express the Phokaian’s self-perception. The concluding chapter rephrases many of the examples into a rich description of Malkin’s small Greek world hypothesis, which shows strong similarities to his previous work on the emergence of Greek identity but now seen from a network standpoint.

The sheer number of examples and the detail to which they are described makes the book’s narrative difficult to follow in places. Indeed, for most chapters the approach taken and crux of the argument are not clearly stated in the introduction and conclusions. At times this leads one to loose track of the bigger picture and the general aim of the book. The figures are of high quality although they are limited (with the exception of chapter one) to maps indicating the places mentioned in the text.

The descriptive first aim of the book is definitely achieved, through the identification of historical links, networks and problems that are better served by a networks approach. The second aim of interpreting the implications of the network perspective is very thorough as far as the description of the small world hypothesis is concerned. In this reviewer’s opinion, however, it does seem underrepresented in one important respect: the absence of convincing argumentation why the emergent property that is “Greek civilization” could not have emerged on a “Greek Wide Web” with a structure other than the hypothetically identified small-world. Malkin’s discussion of the alternative network structures advocated by Braudel (pp. 42-44), Horden and Purcell (pp. 44-45), and Jean-Paul Morel (p. 153) does not give the impression that the likeliness of his hypothesis is any greater. On the other hand, Malkin rightly argues that dynamic network processes add explanatory power to these structures, and he illustrates this throughout the book for his own hypothesis. Malkin seems to be very aware of this issue when stressing that “The identification of connections and particular networks falls within the historian’s search for ‘what was there’ (the factual, or the truth level); the suggestion that network dynamics forms the Greek ‘small world’ is by contrast an interpretation, but to my mind it is one that has a high probability of being right” (p. 207). Yet the book too often reads like a summing up of historically attested ties in a one-to-one relationship with complex network concepts that are by no means exclusive to small-worlds (e.g. emergence, self-organization, hubs, fractal patterning, preferential attachment, decentralization, multi-directionality, phase transitions, clustering) to allow for disregarding alternative network structures out of hand. The innovative network perspective is also only to a limited degree utilised to revisit concepts like ethnicity, Greek civilization, and identity. It is a new hypothesis that focuses largely on explaining past processes of emergence from given states.

Malkin, therefore, piles up evidence for his hypothesis to create the fascinating concept of the small Greek world, which will no doubt prove a rich and useful perspective for future research. However, he does not increase its credibility through falsifying other possible structural incarnations of this network approach. ‘A Small Greek World’ illustrates the potential of a network perspective for understanding the emergence of Greek culture and identities (concepts that themselves are by no means less ambiguous than the ‘small Greek world’ hypothesis), but it is really only a starting point that requires further formalisation and explicit confrontation with the implications of alternative hypothetical network structures.

Social Media in Live Events publication

Screen shot 2012-12-06 at 16.25.46I wrote a few times already about the SMiLE project led by Lisa Harris and Nicole Beale that I am part of. The team presented at the Personal Learning Environment (PLE) conference a few months ago and the paper of that presentation is now included in the online proceedings. You can access the full version on the PLE website or through my bibliography. The paper presents some early findings on our social media strategy applied to the CAA conference 2012 in Southampton.

More cool stuff is to come from the SMiLE team, and we have some great innovative network analysis things in the pipeline, so stay tuned 🙂

Harris, L., Earl, G., Beale, N., Phethean, C., & Brughmans, T. 2012. Building Personal Learning Networks through Event- Based Social Media : a Case Study of the SMiLE Project The Growth of the “ Backchannel ”. In PLE Conference Proceedings, Personal Learning Environment Conference 2012, http://revistas.ua.pt/index.php/ple/article/view/1.

In this paper we report on early findings of our SMiLE project which is evaluating how effective various online social networking channels can be in supporting how people network and learn from a major ‘live’ conference. The event took place at the University of Southampton in March 2012. We consider the dynamics of the relation- ship between ‘real’ and ‘virtual’ communities in the development of personal learning networks, for example how social networking impacts upon participants’ interaction and engagement before, during and after the event as the community of practice de- velops. Assessing the impact of social networking activity on ‘real world’ outcomes has historically been a difficult task, but we argue that recent developments in social network visualisation and analysis now enable valuable insights to be generated for the benefit of both event organisers and attendees seeking to build their subject knowledge and extend their networks.
We begin with a brief review of networking theory and the emerging role of the
online backchannel at ‘live’ events, before describing the approach we took to the col- lection and analysis of social media data from the CAA Conference. We then discuss the implications of our findings for people looking to build learning networks through the increasingly blurred boundaries of ‘real’ and ‘virtual’ networks. We conclude by highlighting some lessons learned and possible directions for future research. Our findings also have relevance to the PLE conference itself – which this year has the added dynamic of two face to face locations for the conference operating at the same time to pose new multi-channel communication and learning challenges for partici- pants.

Review of ‘An Archaeology of Interaction’ in Antiquity

My review of Carl Knappett’s recently published book ‘An Archaeology of Interaction: network perspectives on material culture and society’ has appeared in the June issue of Antiquity. For the official published version, please access the Antiquity website. I have written a much more extensive and unreviewed earlier version as well, which I would like to share with you here:

CARL KNAPPETT. An archaeology of interaction: network perspectives on material culture and society. x+251 pages, 50 illustrations. 2011. Oxford: Oxford University Press; 978-0-19-921545-4 hardback £60.

With An Archaeology of Interaction Carl Knappett wrote a much-needed book that provides both an overview of existing approaches to human interaction as well as a new networks perspective. The key issue addressed in the book is that theories of human interaction generally do not incorporate materiality. The author suggests network thinking as a perspective that succeeds in combining theoretical and methodological approaches to interaction in a single framework and ‘foregrounds the relations between objects and people more effectively’ (p. 7). Much of the book is concerned with exploring approaches from a range of disciplines in the social and physical sciences, and their potential to contribute to this framework. Indeed, Knappett argues that the relevance of An Archaeology of Interaction is by no means restricted to the archaeological discipline, but aims to illustrate the potential archaeological contributions to understanding social interactions in general. A number of issues considered crucial for this new approach to interaction are stressed again and again throughout the volume: the incorporation of materiality, the need to consider assemblages of objects rather than objects in isolation, and the crossing of scales of analysis. Carl Knappett’s search for compatible theoretical ideas and methodological techniques takes him on an explicitly multi-disciplinary journey guided by a clear research question based on a few critical issues and illustrated throughout with archaeological examples (largely from the Bronze Age Aegean). All of this results in a highly readable volume that is both close to exhaustive in its description of issues and approaches, as well as focused on providing an innovative, but above all useful, framework for understanding social interactions.

The book has three parts and each of these consists of three chapters. The first part provides a strong and convincing argument for the need of new methods and theories for understanding human interactions, by stressing the absence of objects in existing theories, highlighting issues in existing relational approaches in archaeology and suggesting network analysis as a formal method for network thinking. In the first chapter the general context of archaeological as well as non-archaeological thought within which this book was written and to which it tries to contribute is laid out. It states that humans have a drive to interact with each other as well as with objects. Knappett suggests network thinking as a research perspective to understand these interactions and argues that ‘By combining SNA [Social Network Analysis] with ANT [Actor-Network Theory] we can bring together people and things both methodologically and theoretically’ (p. 8). The second chapter highlights some broad trends in the dynamics between relational and non-relational approaches to interaction in archaeology and the social sciences. Relational approaches are generally restricted to a single analytical scale and are performed either from the bottom-up or from the top-down. The author argues that concepts and methods are needed to traverse multiple scales. In the third chapter it is suggested that a networks perspective might provide such concepts and methods. An overview of some formal network analysis techniques is given, with a particular focus on affiliation networks, and some existing archaeological applications are briefly discussed. Knappett concludes that, on the one hand, network analysis has a number of advantages: (1) it forces one to think through relationships, (2) it is explicitly multi-scalar, (3) it can integrate social and physical space (topology and geometry), and (4) both people and things can be included. The author does not forget to mention some of the potential issues with the archaeological use of formal network techniques, however: firstly that network analysis is itself by no means a unified social theory, exemplified by the academic divide between SNA and social physics; secondly that the advanced level of mathematics might surpass the abilities of many archaeologists; and thirdly, there is a clear tendency to be overly structuralist and descriptive.

Throughout the second part of the volume the potential of a multi-scalar networks perspective to interactions between people and objects is explored, with chapters focusing in turn on micro-, meso-, and macro-scales of analysis. The case studies used to illustrate Knappett’s approaches are mainly drawn from the Cretan Bronze Age, the author’s area of expertise. In chapter four Knappett argues that existing approaches to interaction at the micro-scale (including interactionism and praxeology) need to be elaborated by reconciling two aspects of micro-scale interactions: ‘the face-to-face social interactions in which objects seem to be in the background; and the individual-object interactions in which sociality seems to fall into the background’ (p. 68). He goes on to suggest an approach aimed at mapping out hypothetical relations between objects (e.g. pottery types) and people (e.g. potters) as affiliation networks. The author explores this approach in a case study aimed at understanding the changes in micro-scale practice that occurred with the shift from ‘Prepalatial’ to palatial society, focusing in turn on practices of production, distribution and consumption. The author does not use the network as an analytical tool for the study of meso-networks, however, to which he turns his attention in chapter five. Network thinking at this scale is applied through a combination of Peircean semiotics with ‘communities of practice’, an idea which is considered to have useful links with the affiliation networks approach of chapter four. Examples from the archaeology of Bronze Age Crete are used to trace such ‘communities of practice’ by describing trends in the similarities and differences between the distributions of spaces, features and artefacts that might be indicative of production, distribution and consumption practices. Knappett then goes on to argue in chapter six that it is on the macro-scale that ‘network thinking comes into its own’ (p. 124). By giving the example of the popular strength of weak ties and small-world network models he argues that at this scale it becomes particularly clear that the relationship between the structure of a network and its function is not trivial. At this level of analysis we can begin to see how macro-scale structure emerges from micro-scale interactions and why, i.e. what function gives rise to a specific structure. Knappett mentions that dynamic network models are particularly useful for exploring hypothetical processes that give rise to certain network structures. He illustrates this through a discussion of his collaboration with the theoretical physicists Tim Evans and Ray Rivers, which resulted in a network model for maritime interaction in the Middle Bronze Age Aegean. He subsequently extrapolates the object-people networks approach introduced in the previous two chapters to a wider spatiotemporal scale, by looking at the evolution of patterns of production, distribution and consumption from the Prepalatial to the Palatial periods in the southern Aegean.

The first two parts of the book set out a framework for exploring how humans interact based on network thinking. The third part moves away from discussions of how to create and explain hypothetical network structures of objects and people to ask why it is that humans interact in the first place. Three alternative approaches are suggested. In chapter seven Knappett discusses the benefits of object networks. A number of concepts are introduced that place the relationship between object and agent central, and the author sees particular potential for cognitive archaeology approaches combined with ‘exaptive bootstrapping’ applied to typological data (pp. 155-158). Through a number of archaeological examples Knappett then explains trends of change in types of artefacts through these concepts. A second approach is suggested by the author in chapter eight as finding ways to attend to the tension between the type of ‘networks of objects’ described in chapter seven and ‘meshworks of things’, a more fluid understanding of the topology of relationships as suggested by Tim Ingold. In the last chapter Knappett argues that one particular way of thinking about this tension is through the care invested by human groups in human and non-human biographies. The author stresses the need to consider biographies of assemblages rather than just individual objects.

The aim and scope of the book are ambitious to say the least and it is therefore not surprising that as a result in places the arguments are not as convincing as they could be. The underrepresentation of method and how theory could inform method, although a major theme in the book, are particularly vulnerable to this mild criticism (especially in the third part). Indeed, archaeologists might not always find the suggested network methods and their archaeological examples very persuasive (as Knappett himself admits, p. 215). They are largely limited to visualising archaeological hypotheses as networks or describing general trends in the archaeological record by using a relational vocabulary. I believe this is a necessary evil, however, in light of the sheer number of approaches covered, and it certainly does not impede the methodological examples from illustrating their most important contribution to Knappett’s network perspective: they do successfully show their obvious potential for expressing and analysing relational hypotheses by thinking explicitly through networks. Carl Knappett’s An Archaeology of Interaction provides a critical and much-needed framework, offering a range of methods and theories to any scholar ready to explore human interaction through network goggles.

Arts, Humanities, and Complex Networks ebook now out!

Leonardo (the International Society for the Arts, Sciences and Technology) and MIT Press produced a new ebook that confirms the Arts and Humanities finally form a valuable part of the growing group of disciplines often associated with complex network research. The ebook edited by Maximilian Schich, Roger Malina and Isabel Meirelles is a collection of 26 short articles based on presentations at the Arts, Humanities, and Complex Networks Leonardo Days at the NetSci conferences, the High Throughput Humanities conference, and most were previously published in Leonardo journal. The works by specialists in fields as diverse as archaeology, history, music, visualisation and language studies illustrate that the Arts and Humanities can make original contributions to complex network research and provide fascinating new perspectives in a wide range of disciplines. A nice online companion was launched together with the ebook.

The volume includes two contributions by researchers from The University of Southampton: the Google Ancient Places project is discussed by Leif Isaksen and colleagues, and the Urban Connectivity in Iron Age and Roman Southern Spain project was introduced by Simon Keay, Graeme Earl and myself. You can find a draft of that last article on my bibliography page.

You can order the ebook on Amazon.

Do check it out!

Here is the full table of contents:

Preface by Roger Malina
Introduction by Isabel Meirelles and Maximilian Schich

I Networks in Culture

Networks of Photos, Landmarks, and People
David Crandall and Noah Snavely

GAP: A NeoGeo Approach to Classical Resources
Leif Isaksen et al.

Complex Networks in Archaeology: Urban Connectivity in Iron Age and Roman Southern Spain
Tom Brughmans, Simon Keay, and Graeme Earl

II Networks in Art

Sustaining a Global Community: Art and Religion in the Network of Baroque Hispanic-American Paintings
Juan Luis Suárez, Fernando Sancho, and Javier de la Rosa

Artfacts.Net
Marek Claassen

When the Rich Don’t Get Richer: Equalizing Tendencies of Creative Networks
John Bell and Jon Ippolito

The Mnemosyne Atlas and The Meaning of Panel 79 in Aby Warburg’s Oeuvre as a Distributed Object
Sara Angel

Documenting Artistic Networks: Anna Oppermann’s Ensembles Are Complex Networks!
Martin Warnke and Carmen Wedemeyer

Net-Working with Maciunas
Astrit Schmidt-Burkhardt

Network Science: A New Method for Investigating the Complexity of Musical Experiences in the Brain
Robin W. Wilkins et al.

Networks of Contemporary Popular Musicians
Juyong Park

III Networks in the Humanities

The Making of Sixty-Nine Days of Close Encounters at the Science Gallery
Wouter Van den Broeck et al.

Social, Sexual and Economic Networks of Prostitution
Petter Holme

06.213: Attacks with Knives and Sharp Instruments: Quantitative Coding and the Witness To Atrocity
Ben Miller

The Social Network of Dante’s Inferno
Amedeo Cappelli et al.

A World Map of Knowledge in the Making: Wikipedia’s Inter-Language Linkage as a Dependency Explorer of Global Knowledge Accumulation
Thomas Petzold et al.

Evolution of Romance Language in Written Communication: Network Analysis of Late Latin and Early Romance Corpora
Alexander Mehler et al.

Need to Categorize: A Comparative Look at the Categories Of Universal Decimal Classification System and Wikipedia
Almila Akdag Salah et al.

The Development of the Journal Environment of Leonardo
Alkim Almila Akdag Salah and Loet Leydesdorff

IV Art about Networks

Tell Them Anything but the Truth: They Will Find Their Own. How We Visualized the Map of the Future with Respect to the Audience of Our Story
Michele Graffieti et al.

Model Ideas: From Stem Cell Simulation to Floating Art Work
Jane Prophet

Culture, Data and Algorithmic Organization
George Legrady

Cybernetic Bacteria 2.0
Anna Dumitriu

Narcotic of the Narrative
Ward Shelley

V Research in Network Visualization

Building Network Visualization Tools to Facilitate Metacognition Incomplex Analysis
Barbara Mirel

Pursuing the Work of Jacques Bertin
Nathalie Henry Riche

New Human Origins journal launched

A new open-contents journal edited by members of the Centre for the Archaeology of Human Origins here at Southampton was just launched. You can download all the papers of the first issue on the new website. This first issue includes papers from the Lucy to Language seminar series. It includes some fascinating papers by my colleagues here. The journal also welcomes new submissions, guidelines can be found on the website.

Human Origins is a British-based peer-reviewed interdisciplinary journal dedicated to human origins research and Palaeolithic archaeology. Funded by the Arts and Humanities Research Council, we offer a broad and interdisciplinary emphasis on Palaeolithic archaeology as well as primatology, osteology, evolutionary psychology, ethnography, palaeo-climatology, geology, anthropology and genetics (phylogeography).

Issue 1 has now been published and is a special volumecontaining papers from the British Academy Lucy to Language: Archaeology of the Social Brain Seminar Series on Palaeolithic Visual Display.

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