Abstract
Scale is a popular science book that tackles major questions from the origins of ageing and death to rapid urbanization and global sustainability challenges, all through the lens of a theoretical physicist. The book follows the evolution of the research interests of its renowned author, Geoffrey West, and their manifestation in his scientific trajectory and output, offering a consolidated overview of West’s and his collaborators’ research findings. Acknowledging the seminal role of the scaling laws framework in developing ‘a unified picture of the elementary particles and fundamental forces of nature’ (p. 7), the author takes off to explain the implications of the scaling framework, first for the biological arena, and then for the social world and sciences. The book certainly offers an enjoyable reading experience for its targeted broader audience. I believe that it also offers an intellectually stimulating exercise and provides discursive ground for researchers engaged with the sustainability sciences field, including spatial planners.
Scale begins with the broadly accepted assumption that almost all natural and social systems are interdependent Complex Adaptive Systems (CASs) ‘composed of enormous numbers of individual constituents [. . .] connected, interacting, and evolving via network structures over multiple spatial and temporal scales’ (p. 6). A typical characteristic of these systems is that their behaviour emerges from the self-organization of their constituents or agents and as such, it is difficult to understand and predict. This is exactly West’s entry point: the challenge of understanding and predicting CASs’ behaviour. This is a rather important and urgent issue considering its implications for future-oriented decision making in a variety of domains from medicine to climate change. In this respect, planning, as a ‘means through which we construct the future’ (Byrne, 2003: 171) in its broader sense, lies in the heart of the book.
After an introduction to the main concepts and the rationale of the book (Chapter 1), in Chapters 2, 3 and 4, the author dives into the concept of scale and the scaling theory framework using examples from everyday life, engineering problems, and, most importantly, biology. In biology, already since 1932, the physiologist Max Kleiber empirically observed that the metabolic rate of organisms (i.e. the rate at which energy is needed to sustain an organism) scales sublinearly with size with an exponent of 3/4. This is a manifestation of the so-called ‘economy of scale’, according to which organisms bigger in size are more energy efficient than smaller ones. Since then, similar patterns of scaling behaviour were observed for different features of biological organisms. In the words of the author, ‘data across all scales and all forms of life were compiled and analysed and it was unanimously concluded that quarter-power scaling was a pervasive feature of biology’ (p. 98). As the author often repeats when discussing different examples of such scaling laws, this systematic behaviour suggests the existence of some underlying mechanisms, which seem to operate similarly across the different (biological) CASs. It is the investigation of those underlying mechanisms that constitutes the essence of the scaling theory framework since they can provide explanations and give insights useful to predict the evolution of essential features of CASs, according to West. Moving from physics to biology, West and his colleagues provided their mathematical explanation for those mechanisms using the lens of network theory and analysing biological CASs as fractal-like, hierarchical network systems transporting energy and resources. All this is vividly presented in the above-mentioned first chapters of the book.
Since the development of the scaling theory framework in biology, West and his colleagues have moved on and applied this same framework to cities, which have traditionally been a popular CAS case for physicists and complexity theory researchers (e.g. Allen, 1981). Thus, Chapters 5 to 8 are focused on cities and are certainly of more interest to spatial planners, who probably have the right to become critical at this point. In Chapter 5, West justifies the choice of the city as a timely object of study and introduces the readers to major aspects of urbanization. His working definition of a city is missing though and this could be considered fundamental information for the reader to be able to contextualize the discussion and findings later in the book. In Chapter 6, the author presents an overview of urban planning and architecture theories and research aiming at a first qualitative ‘testing’ of the scaling theory framework’s relevance to cities. The chapter concludes that the historical references to analogies between cities and biological concepts are probably more than just qualitative metaphors and that ‘cities might also be scaled versions of one another in much the same way that mammals are’ (p. 251). Considering that a fundamental assumption of the book is to analyse cities as CASs, some reflection on the related advances and insights originating from architects, urban researchers and urban planners would seem necessary at this stage. For instance, the works of Christopher Alexander and Bill Hillier, the knowledge encapsulated in books such as Complexity Theories of Cities Have Come of Age (Portugali et al., 2012), and a careful consideration of Michael Batty’s research – rather than a very brief reference to him in Chapter 7 (p. 294) – should probably be somehow acknowledged in Chapter 6 and then put ‘in dialogue’ with West’s assumptions and findings in the later Chapters 7 and 8. Although it would be wrong to expect an exhaustive review of this literature in the specific book, more careful engagement with the existing knowledge and theories throughout Chapters 5 to 8 could further support the interdisciplinary character of West’s work and further strengthen his contribution.
Chapter 7 is the main chapter of the ‘urban section’ of the book, where the scaling theory framework is applied to cities and the related findings are presented. West’s findings suggest that cities do exhibit ‘universal’ power law scaling but with some crucial differences from biological systems. In mathematical terms, the analysis of empirical data shows that as far as their overall infrastructure is concerned (e.g. roads, gas stations), cities behave like biological organisms scaling sublinearly with city population size (i.e. the physical characteristics of the city increase at a slower rate than the city population). Thus, big cities take advantage of the ‘economies of scale’ and achieve savings on infrastructure-related costs. On the contrary, cities’ socio-economic quantities (e.g. average wages, amount of crime and number of patents) scale superlinearly with city population size (i.e. the city’s socio-economic quantities increase at a higher rate than the city population). To understand these results, the author and his colleagues again use network theory and analyse cities as fractal-like physical infrastructure network and social network systems. Based on this analysis, the author suggests that socio-economic quantities are ‘the sum of the interactions or links between people’ (p. 318) and as such they normally increase faster than the city population size, explaining the superlinear behaviour mentioned above. He also concludes that there is a very specific relationship between infrastructure and social networks and that in fact, ‘the sublinearity of infrastructure and energy use is the exact inverse of the superlinearity of socioeconomic activity’ (p. 323). The analysis provided by the author when presenting these results seeks to capture cities as CASs through the three main dimensions of space, time and human agency, and following the flow of resources and information. Nevertheless, in my view, such conceptualisations are generally familiar to those working on complex socio-spatial systems, and West eventually fails to use them to offer a clearer, more insightful explanation on the actual social mechanisms underlying the power law scaling in cities. We have to acknowledge though that the author is aware that more work is needed in this direction, especially when it comes to further understanding social networks (p. 316). In addition, the nature of the book, which is targeted at a lay audience, does not permit a more comprehensive view on West’s assumptions and mathematics. In any case, it is possible and normal that a social scientist could be a bit confused at this point about the relevance of West’s work to social sciences’ queries. The ‘coarse-grained’, in West’s vocabulary, findings do not seem to be of much direct instructive value yet and certainly leave unspoken complex social phenomena and context-specific issues of high interest to social scientists. In the next paragraph, I will briefly discuss what I perceive as the main instructive aspects of the book.
Chapter 9 briefly refers to the application of the scaling theory framework to companies, which is an effort still in its infancy, but a promising venue for further research, according to West. Chapter 10 provides concluding remarks. There, the author highlights, in my opinion, the main message of this book for spatial planning and beyond. Through the whole of his analysis, West gradually builds a very specific argument on the phenomenon of ‘growth’ related to humans both as biological organisms and social agents. He finally concludes with the normative and highly political suggestion that there are limits to growth and that the open-ended growth paradigm, which is the primary assumption upon which modern cities and economies are based, is very likely to be unsustainable in the long term (pp. 412–426). This conclusion and the author’s reservations about the eternal ‘safety net’ of technological innovations could be considered an important addition to the growing calls for (social) changes of a ‘transformative’ nature in light of global environmental change (Fazey et al., 2018; Pelling et al., 2015). In this respect, spatial planning, which inherently deals both with emergent and directed change, seems to be asked to evolve accordingly and further engage not only with the concepts of complexity, energy and entropy, as West suggests, but also with contributing to developing a theory and practice of such transformative change at different spatiotemporal scales. This effort would not be developed solely by spatial planners but within the framework of the sustainability sciences to which West aims to contribute with this book. Despite his narrow definition of ‘science’, West values inter- and trans-disciplinarity (p. 431) and he probably ‘needs’ them as approaches considering his ambition ‘to inform the underlying science that is needed for addressing these (sustainability) challenges so as to inform rational political decisions’ (p. 245). After all, sustainability and urban problems demand problem-solving strategies that draw on West’s science while enriching it with other bodies of relevant legitimated facts and with perceptions informed by diverse values and normative standpoints (Frame and Brown, 2008). Thus, it would be interesting to see this scaling theory framework, originating from a physicist’s point of view, interact with complementary or alternative approaches to cities and sustainable development challenges, originating from a planning lens.
To conclude, the book offers a highly interesting read in a renaissance spirit that cuts across disciplines and connects science to everyday life, popular culture, questions of life, death and sustainability issues. Planners should read the book not only with an open mind to appreciate West’s multi-dimensional reflections but also with a critical lens. I believe that the book Scale aims at inspiring doubts, questions and new avenues for research rather than providing absolute answers and it is rather successful in this direction.