1This is a book of very great interest, the result of an ambitious and innovative project, which will constitute a landmark. Starting from the hypothesis that it is the multiple transitions in the organisation of societies which comprise the backdrop to the long-term history of humanity, this book attempts to identify them, define them, and understand their dynamics by way of the spatial organisation specific to each step.

2This project, and this book, have brought together a large team, whose senior members are all eminent researchers in their own disciplines, but with broader transdisciplinary interests. They are supported by a large number of younger researchers.

3The interest of the book is three-fold. First of all, it combines observation, analysis and modelling of the different dynamics and stages of that history, starting from a collection of archaeological, geographic and historical data, using a range of techniques of statistical analysis and modelling which have been developed over the past twenty years (in part, moreover, by the coordinator and her team). Thus, it is a work which demonstrates in exemplary fashion at once the interest and the potential of a transdisciplinary approach.

4Next, it covers the entire history of human societies, moving from the small groups of hunter-gatherers of the Palaeolithic to the first agricultural societies of the Neolithic, the first cities of the Bronze Age and the imperial societies. The volume thus covers the largest possible gamut of human societal forms of organisation. By doing so from a well defined point of view (that of space), it enables comparisons to be made between these forms of organisation, thereby enabling theories to be developed on the subject.

5By basing itself on modelling, finally, the book makes it possible – something rare in archaeology and history – to go beyond static studies of the different forms of organisation to study the dynamics which are responsible for them, and therefore to help understand the transitions between different phases and write a process-based history of the emergence of human settlement in all its forms.

6The work is divided into three parts. The first part stresses the importance of studying transitions. In our archaeological culture we have long studied the different stages of human evolution without having at our disposal the tools for conceiving and studying the dynamics of transition between those different stages. By combining the historical sciences and computer sciences, modelling at last permits us to do this. A transdisciplinary approach is therefore fundamental. To implement it, the work develops a conceptual framework and the definitions that permit the disciplines concerned to converge. Necessarily, this framework focuses on the dimensions of time and space, which are fundamental. This permits the authors to compare a number of spatio-temporal strategies for modelling transitions.

7In the second part, the authors present models of diverse spatio-temporal dynamics, ranging from the colonisation of new territories by Homo sapiens in the Palaeolithic, to the functional dynamics responsible for the emergence of the polycentric ‘mega-cities’ of our age. This allows them to take up several fundamental challenges of human history:

• The problem of the adaptation of populations to new habitats, whether the latter are uninhabited or inhabited by populations with a way of life profoundly different from that of the new colonisers.

• The evolution of agricultural societies from small relatively egalitarian colonies to the formation of groups structured more or less hierarchically.

• The role of the dynamics between society and environment which are essential for all societies, illustrating these by way of the Pueblo societies of the southwestern United States.

• The important transitions of the history of western Europe, notably those of the Iron Age, of Romanisation, of the end of the Roman Empire, and of the emergence of medieval, modern and contemporary landscapes. Each is described in detail on the basis of the data available, with the description followed by a formalisation which raises precise questions calling for answers. This permits the authors to define these transformations against a background of multi-millenary environmental continuity.

8Certain of these chapters introduce new approaches to modelling, such as MASQ (Multi-Agent Systems based on Quadrants), and also one which, in my view, represents a very important advance in the modelling of urban systems: the latest offspring of the SIMPOP series of models developed, beginning in 1996, by the Géographie-cités team: SIMPOP LOCAL, which presents the interest of exploring (on the basis of 500 million executions) a great number of potential states of the settlement system using a limited number of parameters, and of validating them by methods still hardly known in these circles. But the team also uses well established approaches, both conceptual and to simulation – for example, game theory and multi-agent models. As a consequence, the volume as a whole opens the way to a far more detailed understanding of a broad range of behaviours, not only spatial, but also social.

9The third part presents an in-depth discussion of the interaction between disciplines, between diverse categories of data, between diverse definitions of transitions, between models and narratives, and between modellers and thematicians. This constitutes a rich reservoir to draw on for all those having the ambition to implement a large transdisciplinary project, but it is also grist to the mill of worldwide scientific initiatives, such as Future Earth, which aim at launching a vast undertaking of co-creation and co-construction in the field of global change. Among the questions of epistemology and method which this section raises, let me signal a few which seem to me of fundamental importance:

• ‘Why do we make an effort to model transition without also modelling the phases of relative stability between them?’: modelling stability and transition at the same time with the same models would give us a still richer perspective on the regulatory mechanisms of our societal constructions.

• ‘What are the respective roles of narratives and models in the Social and Human Sciences?’, and, especially, ‘What is the relation between the narrative and the model?’, ‘What is the validity of the generalisations that underlie a model?’ ‘How can rigour and uncertainty be associated in modelling?’

• ‘What are the relations between the concepts of time and of space?’: the subject is obviously fundamental for all our social disciplines but is rarely dealt with in archaeology (see the magnificent book of Laurent Olivier, Sombre abîme du temps.1

• ‘What are the role and the nature of innovation?’: a crucial subject, if one considers the social transitions, but a subject which touches on in archaeology in a descriptive manner or in evoking a vague and often outmoded concept of evolution.

• ‘What is the role of models in transdisciplinary collaboration?’ ‘What are the advantages and disadvantages of working in a transdisciplinary team with distributed responsibilities, compared with working individually?’

• And, finally, a question of great importance in every attempt at modelling in the Social and Human Sciences, where quantifiable data, like the quantified results of modelling, are subject to significant uncertainties: ‘What is the relative value of reproducing measurements and of reproducing a reasoned argument’?

10In sum, I judge this to be a work of great importance. The richness of its opinions and ideas on points and questions of substantial interest makes it a volume which will transform our perspectives on the human past, but also a volume with a methodological impact in geography, archaeology and the Social and Human Sciences generally. I am sincerely pleased to see it translated into English, for, taken as a whole, it goes beyond anything I have seen published in that language.