Change, Helm, an economist at the University of Oxford, UK, agrees that the policy outlook for stabilizing atmospheric concentrations of carbon dioxide and other greenhouse gases is "very grim" owing to the myriad complexities and contradictions of policies for reducing emissions globally. He argues that far more than political will is required to make progress on this issue, the magnitude of which has been underestimated. A "fundamental rethink" is needed, he says, with a greater focus on international and long-term technological solutions. Other authors who contribute to this impressive volume highlight the challenges of securing a global agreement. Economic growth, suggest Australian economist Ross Garnaut and his colleagues, has entered not just a golden but a "platinum age" that, beyond the current recession, is likely to continue for decades. If so, then the IPCC assessments have under estimated the challenge of emissions reduction, its costs and the mitigation potential of existing technologies. Chapters on India and China reinforce this perspective. Helm and his co-editor Hepburn, also an economist at the University of Oxford, admit that their book "is not intended to provide simple answers". It presents a range of options that might each contribute to decarbonization of the global economy. These include cap-and-trade regimes, carbon taxes, behavioural change, nuclear energy, carbon capture and storage, renewable-energy technologies, sequestration in forests, improving energy efficiency and geoengineering. Each method has its merits, flaws and opposition. The bottom line is that although we have plenty of options with which to embark on the challenge of responding to climate change, we are nowhere close to a complete solution. Together, these four books highlight that climate policy is at a crossroads. The journey so far has emphasized science and exhortation: that facts, spoken loudly enough, are enough to win the argument. That path has succeeded in bringing climate change to the attention of policy-makers and the public as an important global problem. At the same time, that approach has shown its limitations. Climate science has become deeply politicized and climate politics is in gridlock. Climate change is at risk of becoming an issue of cultural politics, similar to the evolution debate in the United States and elsewhere. If the climate-policy debate is to continue as it has, we should expect more of the same. An alternative way forward would start by admitting the limitations of science in compelling political agreements, and by admitting that we do not know how to complete the challenge of decarbonizing the global economy. There may be greater prospects for political consensus if scientists acknowledge their humility rather than asserting their authority. Incremental approaches to climate mitigation that can be modified by experience offer a chance that realistic and democratically grounded actions might rise to a challenge that will be with us for decades to come. Each of these contrasting books offers a valuable perspective on how we got to where we are, but each gives only limited insight as to where climate policy may be going. The future, as Gore says, remains our choice. ! Roger Pielke Jr is professor of environmental studies at the University of Colorado, Boulder, Colorado 80309, USA. His forthcoming book is The Climate Fix. e-mail: pielke@colorado.edu A misguided attack on evolution On the heels of last year's anniversary celebrations of Charles Darwin's On the Origin of Species and C. P. Snow's 'Two Cultures' essay, an interdisciplinary view of evolutionary theory by philosopher Jerry Fodor and cognitive scientist Massimo Piattelli-Palmarini might be anticipated with interest. Unfortunately, What Darwin Got Wrong fails to bridge these two cultures. By misusing philosophical distinctions and misinterpreting the literature on natural selection, Fodor and Piattelli-Palmarini make a mess of what could have been an important contribution. The authors are correct in two of their assessments. Namely that: mainstream evolutionary biology has become complacent with the nearly 70-year-old Modern Synthesis, which reconciled the original theory of natural selection with Mendelian and population genetics; and that the field needs to extend the conceptual arsenal of evolutionary theory. But in claiming that there are fundamental flaws in an edifice that has withstood a century and a half of critical examination, Fodor and Piattelli-Palmarini err horribly. The authors' argument against "Darwinism" boils down to a two-pronged attack. First, they claim that biologists' emphasis on ecological, or exogenous, factors is misplaced because endogenous genetic and developmental constraints play a crucial part in generating organic forms. Second, they argue that natural selection cannot be an evolutionary mechanism because evolution is a historical process, and history is "just one damned thing after another" with no overarching logic. The first claim represents a distortion of the What Darwin Got Wrong by Jerry A. Fodor and Massimo PiattelliPalmarini Farrar, Strauss & Giroux/Profile: 2010. 288 pp/258 pp. $26/£20 A solar-power plant in Wuhan is part of China's plans to produce 10 billion watts of solar energy by 2020. CH IN A D A ILY /R EU TE RS /C O RB IS 353 NATURE|Vol 464|18 March 2010 OPINION 352-355 Books and Arts MH AB.indd 353 11/3/10 17:31:09 © 20 Macmillan Publishers Limited. All rights reserved10 literature. The relative importance of natural selection and internal constraints has always been contended by biologists: molecular and developmental biologists tend to focus on internal mechanisms; ecologists and evolutionary biologists prefer to address external ones. But even Darwin accepted the importance of both: in Origin, his 'laws of variation' acknowledge that variation is constrained, and his 'correlation of growth' implies that organismal traits are interdependent. Fodor and Piattelli-Palmarini misappropriate the famous critique of adaptationism (the idea that natural selection is sufficient to explain every complex biological trait) that Stephen Jay Gould and Richard Lewontin presented in their 'spandrels' paper of 1979. Gould and Lewontin warned about the dangers of invoking natural selection without considering alternatives. But Fodor and Piattelli-Palmarini grossly overstate that case, concluding that natural selection has little or no role in the generation of biological complexity, contrary to much evidence. In their second line of attack, Fodor and Piattelli-Palmarini maintain that biological phenomena are a matter of historical contingency. They argue that generalizations are impossible because of the interplay of too many local conditions, such as ecology, genetics and chance. In their narrow view of what counts as science, only law-like processes allow for the testability of scientific hypotheses. Thus, they claim, an explanation of adaptations that is based on natural selection is defensible in only two cases - if there is intelligent design, or if there are laws of biology analogous to those of physics, both of which they reject. Here the authors ignore the entire field of evolutionary ecology, countless examples of convergent evolution of similar structures in different lineages that show the historical predictability of evolutionary processes, and the literature on experimental evolution, in which similar conditions consistently yield similar outcomes. There is clearly a logic to evolution. Evolutionary biology is a mix of chance and necessity, as French biologist Jacques Monod famously put it, in which endogenous and exogenous factors are in constant interplay. It is a fertile area for rigorous philosophical analysis. Fodor and Piattelli-Palmarini offer only sterile and wrongheaded criticism. Fortunately, other philosophers of science and theoretical biologists are coming together to clarify and build on the conceptual foundations of science and explore issues of its practice; this is a better way to bridge the two cultures. ! Massimo Pigliucci is a professor of philosophy at the City University of New York–Lehman College, Bronx, New York 10468, USA. e-mail: massimo@platofootnote.org A macromolecular history The study of large molecules follows two strands that have alternately diverged and intertwined over the subject's history. The first strand explores the natural macromolecules of biology, including proteins, polysaccharides and nucleic acids. The second is concerned with synthetic macromolecules, the invention of which in the early twentieth century launched industries based on plastics such as nylon, polyethylene and Perspex. In Giant Molecules, biophysicist Walter Gratzer weaves together both stories. Initially the two strands developed together, sharing experimental methods and theoretical approaches. The simpler chemistry of the synthetic materials offered tractable analogues of the natural systems. Then, as the inherent complexity of biological molecules became central to their understanding, the fields split. The flowering of structural biology in the late 1950s and 1960s was driven by the technique of X-ray diffraction and owed little to polymer science. Gratzer describes the history engagingly, and includes many anecdotes. He explains how German chemist Hermann Staudinger's concept of polymers as giant molecules became accepted amid controversy, rancour and the ugly academic politics of German universities in the period up to the Second World War. Not all of the anecdotes he chooses are reliable: he includes, for example, the widely held but incorrect notion that the windows in medieval cathedrals are thicker at their base because the glass has flowed. This lapse is symptomatic of a general weakness in the book when it comes to the physical science of macromolecules. Recent developments in the physics and chemistry of macromolecules get short shrift. The book's discussion of ways of measuring the size of polymer molecules, for example, is many years out of date, and the influential work of those such as Nobel laureate PierreGilles de Gennes, who brought theoretical physics concepts to molecular science, is not mentioned. New methods of polymer chemistry, such as living polymerization, ringopening metathesis and solid-phase peptide synthesis, all of which allow unparalleled control of the size and architecture of synthetic macromolecules, are not mentioned, despite yielding Nobel prizes. In recent years, the two strands of macromolecular science have converged again. Techniques such as laser tweezers and singlemolecule force spectroscopy have allowed us to study the behaviour of biological macromolecules as individual physical objects. Aspects of protein behaviour, such as their mechanical unfolding and the structures they form when they misfold, re-emphasize the analogies between biological and synthetic macromolecules. The increasing ability of chemists to control the architecture of synthetic polymers has made new applications possible, especially in nanotechnology. The new forms of carbon - fullerenes, nanotubes and graphene - earn their place in the book. Gratzer covers the promise of polymer nanotechnology in brief. Some applications - such as glues inspired by shellfish; drug-delivery devices based on self-assembled polymer vesicles; and scaffolds for tissue engineering - are directly inspired by biology. Others, such as the plastic electronics made possible by semi-conducting polymers, use properties of macromolecules that have not been exploited by nature. Arguably, DNA is the most important macromolecule, and I share the author's particular fascination with its potential uses, for example as the basis of synthetic molecular motors, for information processing and to make intricate self-assembled nano-objects. Only time will tell whether such beautiful laboratory demonstrations will yield practical technologies that have the impact in the twenty-first century that plastics had in the twentieth. ! Richard Jones is professor of physics at the University of Sheffield, Sheffield S3 7RH, UK, and author of Soft Machines: Nanotechnology and Life. e-mail: r.a.l.jones@sheffield.ac.uk Giant Molecules: From Nylon to Nanotubes by Walter Gratzer Oxford University Press: 2009. 144 pp. $24.95, £11.99 Tiny capsules made of synthetic polymers can be used to deliver drugs for slow release in the body. A . C AV A N AG H /W EL LC O M E IM AG ES 354 NATURE|Vol 464|18 March 2010OPINION 352-355 Books and Arts MH AB.indd 354 11/3/10 17:31:11 © 20 Macmillan Publishers Limited. All rights reserved