Because this book covers such a vast and varied territory, an unexpected challenge in writing it was to settle on a suitable title that would capture its main message in just a few punchy words or even half a tweet. After floating some rather lame possibilities, such as Size Really Matters, Scaling the Tree of Life, and The Measure of All Things, I settled on the somewhat cryptic title of Scale, because this is indeed a unifying theme of the book. However, “scale” can mean a lot of different things to a lot of different people. For some it connotes maps and charts, for others music, for yet others weighing vegetables or meat, and for some deposits on a rough surface. These were decidedly not what the prime substance of the book was about, so calling it Scale simply deferred the challenge to finding a catchy subtitle that made its intended meaning much more explicit.
Hitting upon a grander image of scale, as in “the scale of the universe,” I came up with the somewhat grandiose subtitle: The Search for Simplicity and Unity in the Complexity of Life, from Cells to Cities, Companies to Ecosystems, Milliseconds to Millennia. This at least captured some of the spirit of the book and in particular the crucial interplay between the big picture “cosmic” perspective and the more focused “real-world” problems that I was addressing. Although this suggestion was a bit of a mouthful, it still didn’t capture many central aspects of the book, which my editor at Penguin Press, Scott Moyers, felt needed to be emphasized. Eventually, after considering several possibilities and variations suggested by Scott, Paul Murphy, my editor at Weidenfeld in the UK, my wife, Jacqueline, and my agent, John Brockman, I settled on what you see on the title page: The Universal Laws of Growth, Innovation, Sustainability, and the Pace of Life, in Organisms, Cities, Economies, and Companies. By far the most creative suggestion came from my son, Joshua, who is a professor in Earth sciences at the University of Southern California in Los Angeles. He suggested the acronymic title SCALE: Size Controls All of Life’s Existence.
It’s pretty catchy, ridiculously hyperbolic, and rather clever and I wish I had had the chutzpah to actually use it. But had I done so, I’m sure it would have been vetoed by both Scott and Paul—and rightly so.
I have approached all of the problems addressed in the book primarily from the viewpoint of a theoretical physicist whose language is mathematics. Consequently, an underlying thread running throughout the book has been an emphasis on developing a more quantitative, computational, predictive understanding based on fundamental principles as a complement to the traditional, more qualitative, narrative arguments that tend to dominate the social, biological, medical, and business literature. Nevertheless, there isn’t a single equation in the book. I took very seriously the admonition of Lord Ernest Rutherford, the famous discoverer of atomic nuclei—“the father of the nuclear age”—that “a theory that you can’t explain to a bartender is probably no damn good.” I’m not entirely convinced that he was right, but I did heed the spirit of what he said. I hope, therefore, that I have succeeded in some small way in keeping the arguments and explanations at an appropriately nontechnical level so that the proverbial “intelligent layperson” didn’t have too much difficulty in following them. In doing so I have had to take a certain degree of poetic license in distilling the essence of complex technical or mathematical arguments to simple colloquial explanations and hope that my scientific colleagues will indulge and condone me for any oversimplifications, misrepresentations, or any subsequent lack of rigor.
The problems, questions, and explanations presented in the book are shamelessly addressed from my own personal perspective. As a result, the book is neither encyclopedic nor a comprehensive review of the enormous literature covering the many subjects and problems that are addressed. A major intent is to show that underlying the extraordinary complexity, diversity, and apparent messiness of the world we live in lies a surprising unity and simplicity when viewed through the lens of scale. Great tomes have been written by deep thinkers about almost everything that is considered in the book and it goes without saying that I am building on what many have already understood and analyzed. I have tried to give credit where appropriate, but I have in no way been comprehensive in referencing all those who have contributed to the development of the ideas and concepts that I explore. In so doing, I hope I have not offended too many people.
Many of the arguments and almost all of the examples used are based on an extensive body of work that I have been intensely engaged in over the past twenty years together with an extraordinarily talented group of colleagues. Not all of the grandiose themes or all of the specific problems that were attacked are given equal billing. Choices needed to be made and some were either neglected or given relatively short shrift. The specific topics and themes that were eventually chosen, and the depth to which they are explored, were determined partly by their conceptual significance, partly because they were judged to be an important topic of general interest, and partly out of my own idiosyncratic perspective. Throughout the book I veered toward emphasizing a bigger picture conceptual framework and explaining basic ideas rather than dwelling on details, though I tried not to shirk from drilling down deeper and presenting such details when I thought it necessary. Consequently, like the scientific enterprise itself, there are many loose ends and unanswered questions. However, the inquisitive reader should have little difficulty in further exploring the territory I have opened up that might be of particular interest by referring to the materials listed at the end of the book.
I interspersed the scientific narrative with occasional anecdotes about some of the key players in the development of various critical concepts that play an important role in the book. I concentrated primarily on a subset of a few remarkable men of broad intellect who changed the way we think about the world but who have not received the recognition they deserve even, in some cases, within the broader scientific community. Names that you might not have heard of, such as Adolphe Quetelet, Thomas Young, and William Froude. I also included a few personal anecdotes to illustrate how I came to think about some of these problems, and, in particular, how I transitioned from being obsessed with elementary particles, strings, dark matter, and the evolution of the universe to trying to understand cells and whales, life and death, cities and global sustainability, and why companies die.
A critical point in this transition was my meeting with the eminent ecologist and wonderful scientist Jim Brown. In chapter 3, I related the story of how this fortuitous encounter and my subsequent long-term engagement with the Santa Fe Institute came into being and how it led to an extraordinary collaborative relationship that changed my life, and I believe his, too. I also recounted the critical role played by Brian Enquist, then a student of Jim’s and now a distinguished ecologist in his own right. Brian was the first of a small stream of outstanding young people who joined our little “scaling group” to work on many of the problems addressed in subsequent chapters: the ecologists Jamie Gillooly, Drew Allen, and Wenyun Zuo; the physicists Van Savage, Chen Hou, Alex Herman, and Chris Kempes; and the computer scientist Melanie Moses. An additional and very important member of the collaboration was the well-known biochemist Woody Woodruff, who has since retired to enjoy the hills of his native Tennessee.
In chapter 7, I recounted how the “cities group” evolved as a natural outgrowth of the scaling group. It actually began as part of a much larger social science project called ISCOM (Information Society as a Complex System), which was generously funded by the European Union. This was a collaboration with the Italian statistician/economist David Lane, the Dutch anthropologist Sander van der Leeuw, and the French urban geographer Denise Pumain, all of whom are senior leaders in their fields. Without their initial stimulus, enthusiasm, and support I doubt if any of this would have happened. The young researchers who did almost all of the analysis on the cities work, which is explained in chapters 7 and 8, were the physicists Luis Bettencourt, Hyejin Youn, and Dirk Helbing; the urban economists José Lobo and Debbie Strumsky; the anthropologist Marcus Hamilton; the mathematician Madeleine Daepp; and the engineer Markus Schlapfer. Other collaborators who were intermittently involved but nevertheless made important contributions and influenced my thinking include the ecologist Ric Charnov; the systems biologist Aviv Bergman; the physicists Henrik Jensen, Michelle Girvan, and Christian Kuhnert; the investment analyst Eduardo Viegas; and the architect Carlo Ratti, whom I talked about in chapter 8.
I have been truly blessed in having each of these as my collaborators and am deeply indebted to all of them. I have deliberately made their individual disciplinary backgrounds explicit so as to highlight the broad transdisciplinary nature of the collaborations that were needed to seriously address the sorts of topics and problems that constitute this book. Their individual and collective commitments and passion for conceptual understanding and for attacking important problems were hallmarks of our ongoing meetings and interactions. Their probing questions and insights, their technical and conceptual contributions, and their willingness to engage in intense group discussions were crucial ingredients to our success. I am sure that some of them may have misgivings about how I have presented the results of some of our work and apologize in advance for any embarrassment or concern that this might cause. I take full responsibility for any mistakes or misrepresentations.
I am delighted to say that all of the young researchers moved on to successful careers at excellent universities, where, among other things, they established their own brand of this kind of science. Two who were particularly important in terms of my own interactions were Van Savage and Luis Bettencourt. This is very likely because both were trained in theoretical physics, so we spoke the same language. Luis, who is now a colleague at the Santa Fe Institute, played a central role in the development of the work on cities, a story that is recounted in some detail in chapter 7. Van, who had originally been hired as a postdoctoral fellow at SFI, eventually left for Harvard before moving on to UCLA, where he has established himself as a leading theoretical ecologist. Among the many problems we had great fun working on together, I want to mention two that are not discussed in the detail they deserve in the book even though both are fascinating, challenging, and very important. One is the development of a quantitative theory of sleep, showing, for example, why whales sleep for just a couple of hours, mice for fifteen, and we for about eight. Together with Van’s bright young student Junyu Cao we recently extended this to understand sleep patterns in babies and children and showed how this framework provides important insights into early brain development. The other problem, carried out in collaboration with Alex Herman, was to develop the first quantitative theory for understanding the growth, metabolic rate, and vascular structure of tumors that we hope will stimulate new therapeutic strategies for attacking cancer.
I’ve probably been a little remiss in not drawing attention to the fact that some of the work in biology discussed in chapters 3 and 4 has not been without its critics. This in spite of, or possibly because of, the significant impact it has had, as evidenced by the numerous citations to it in the literature and the broad attention it has received across the scientific and popular press from the Financial Times to the New York Times. There have been many feature articles about it in high profile media outlets worldwide, including TV channels ranging from the National Geographic to the BBC. It was hyperbolically referred to in Nature as a “biological theory of everything” and “as potentially important to biology as Newton’s contributions are to physics”—though very flattering, this is clearly a highly inflated characterization. In a separate article in Nature it was also stated that “. . . this theory explains so much with so little. It is breathtaking in its ambition and scope. Any new theory that is apparently so omniscient will attract as many grumbles of doubt as gasps of admiration. . . . No comparable idea yet matches it, despite its inevitable limitations.”
In writing the book I made a strategic decision not to directly address the “grumbles of doubt” but rather concentrate on getting the big message across. A major reason for this was that from our biased point of view none of the criticisms was convincing. Some were simply incorrect and many typically rested on a single technical issue in some specific system for which there were often at least equally supportable alternative explanations. Furthermore, almost all of the concerns were focused solely with mammalian metabolic rate, failing to appreciate the great breadth of the framework and that it offers a single parsimonious explanation rooted in basic principles of biology, physics, and geometry for an enormous variety of empirical scaling relations. Needless to say, such criticisms have been dealt with in the scientific literature and can be accessed through references cited below.
It goes without saying that many other colleagues and friends have been enormously important in providing me with the enthusiastic moral and intellectual support and encouragement needed to complete such a book, especially at times when my own enthusiasm waned. The Santa Fe Institute provided exactly the right ambience and cultural mix of colleagues needed for developing most of the ideas that are articulated in the preceding chapters. A few anecdotes about SFI are recounted throughout the book, and part of my afterword is dedicated to extolling its virtues and why I believe that its mission represents an important harbinger of science for the twenty-first century. I am particularly indebted to the wonderfully effervescent Ellen Goldberg, a past president of SFI, for persuading me to join the institute—a move that reset my intellectual clock and gave me a new lease on life. Being exposed to a never-ending flux of extraordinary individuals at various stages of their careers, from students to Nobel Prize winners across a breathtaking spectrum of intellectual and cultural pursuits, was like letting a child loose in a candy store.
In that context I would also like to thank the extended SFI community, both individually and collectively, for broadening my scientific horizons and helping me begin to understand some of the subtleties and challenges inherent in the study of complex adaptive systems. I would particularly like to mention Pablo Marquet, John Miller, Murray Gell-Mann, Juan Perez-Mercader, David Krakauer, Cormac McCarthy, and Bill Miller and Michael Mauboussin, past and present chairmen, respectively, of SFI’s board of trustees, all of whom have given me their unwavering enthusiastic support and encouragement over many years. I am deeply grateful and indebted to all of them. I am particularly grateful to Cormac for painstakingly reading and editing the manuscript in excruciating detail, providing extensive feedback, which helped greatly in improving the final product. Although I accepted most of his advice about grammar and sentence construction, I continue to argue with him over his total aversion to semicolons and exclamation marks; and his insistence on the Oxford comma.
In addition to my close associates I owe a measure of gratitude to an eclectic group of nonscientists who felt that I had something of broad interest to say and enthusiastically encouraged me to write a book for a general audience. It was their feedback that persuaded me to change gears and write a nontechnical “popular” book rather than one directed to my scientific colleagues. Among these are the historian Niall Ferguson; the art curator and critic Hans Ulrich Obrist; the writer-actor Sam Shepard; the founder of Amazon, Jeff Bezos; and the founder of Salesforce, Marc Benioff. I was really touched when Marc sent me a large painting of the Sephirot—the traditional Kabbalistic image representing the spiritual unity of life—suggesting that I meditate upon it each day. I can’t say that I religiously followed his advice but it did inspire me to stay connected to the big picture when the going got tough. In this context I owe particular thanks to the amazing Richard Wurman, the original founder of TED, who has been indefatigable in his enthusiastic appreciation of my work.
Even though theoretical research requires only a pencil and paper—at least metaphorically—it can no longer be done without substantial financial support. I have been very fortunate in receiving funding from several diverse sources in both the public and private sectors for support of much of the research that forms the basis of this book. I am deeply grateful to Los Alamos National Laboratory and the Department of Energy for supporting my exploratory foray into biology while I was still leading the high energy physics program at the lab. At that crucial incipient stage the physics division of the National Science Foundation awarded me a modest grant to pursue research on scaling in biology. I am indebted to Bob Eisenstein, the then leader of the division, and to Rolf Sinclair, the program manager, for sticking their necks out in supporting this line of research, which at the time was rather unfashionable. Over the years the NSF continued its support of the work in biology, extending it to some of our early work on cities. This is in no small part due to the vision of the irrepressible Krastan Blagoev, who later initiated, and still runs, a dedicated program called the “The Physics of Living Systems,” whose aim is to address important problems at the interface between traditional disciplines.
Significant support has also come from nongovernmental sources, including the Hewlett Foundation, the Rockefeller Foundation, the Bryan and June Zwan Foundation, and, in particular, the Eugene and Clare Thaw Charitable Trust. Gene Thaw has been extraordinarily generous in providing support for both the research and, equally important, for the writing of this book. The successive directors of the trust, beginning with the visionary Susan Herter through Sherry Thompson to Katie Flanagan, facilitated a very special relationship. Gene is a remarkable man, a gentleman of the old school who sports cravats and tweed jackets, a man of great culture who truly cares about the world. He is a well-known collector, critic, and dealer who has vigorously supported the arts for many years. He will turn ninety next year and the Morgan Library & Museum in New York will be entirely turned over to exhibit his remarkable collection of drawings ranging from Piranesi and Rembrandt to Cézanne and Picasso, while the Metropolitan Museum of Art will be showing his unequaled collection of Native American art and artifacts. Gene’s passion for opera and the arts is equaled only by his passion for the environment and the challenge of global sustainability and it is in this context that he volunteered to support our research. He is the nearest embodiment I know of to a traditional patron—his support for my research agenda gave me the freedom to explore wherever my imagination and curiosity took me as I embarked on writing this book. I take great pleasure in thanking him for his generosity and patience.
In addition to the ongoing support of the Thaw trust it is also true that the book would not have been written without the urging and cajoling of my agent, the inexorable John Brockman. I’m still not entirely sure why but he was determined that I write a book. It’s been a long haul during which John, and now his son, Max, has been there with me and I am hugely grateful for their support. John gently bullied me into writing the original proposal for the book, which was eventually completed at the spectacular Rockefeller Foundation retreat in Bellagio, Italy. This was exactly the right setting and I am extremely grateful to the foundation for hosting my wife, Jacqueline, and me there for a month—it was extremely productive. Even though the Rockefeller Foundation does not generally support basic research, it was also very generous in providing major funding for our work on cities. The president of the foundation, Judith Rodin, was very supportive, but we have to thank our program officer at the time, Benjamin de la Pena, for fighting hard on our behalf.
The book would not have been completed, and it certainly would have been much less coherent, had it not been for my wonderful editor at Penguin Press, Scott Moyers. He worked relentlessly on my behalf, always encouraging, always thoughtful, and always gentle even when being critical . . . and always remarkably patient and understanding. He must have been horrified as he saw this book grow from its originally projected modest size to something gargantuan, taking twice as long to complete as anticipated. His meticulously detailed editing of the manuscript, his probing questions, and his wise advice were invaluable. Scott, I cannot thank you enough. In addition to Scott, the entire team at Penguin Press was marvelous: Christopher Richards and Kiara Barrow aided by Thea Traff at the New Yorker were critical in getting all of my garbled illustrations and edits straight.
Finally, I take enormous joy in thanking my family for its tremendous support and patience throughout this long process. Our wonderful children, Joshua and Devorah, have been cheering me on from the sidelines, providing encouragement each time I dropped the ball and wildly celebrating the occasional touchdown. I’m sure they will be relieved now that this book is behind me. My deepest appreciation is owed to my extraordinary wife, Jacqueline, who has been my moral, spiritual, and intellectual companion not just in the writing of this book but throughout our remarkable journey together that has now lasted for almost fifty-five years—and what a journey it has been! Her honesty, intelligence, and profound love have been the mainstay of our life together, providing a depth to the meaning of life complemented only by the eternal search for understanding.