Books & arts graphics in Narrative Economics and those in he was also a visionary. In his essay ‘Economic attempting to “lean against false or misleading his bestselling book Irrational Exuberance Possibilities for Our Grandchildren’ (1930), narratives and establish a moral authority (2000). But the message is effective: the value he foresaw a time when our society would against them”. Roosevelt’s remark was designed of your story might go up as well as down. move beyond growth. It hasn’t happened yet to “create and disseminate counter narratives The empirical core of the book is a detailed — in spite of economist Kenneth Boulding’s that establish more rational and more pub- exploration of numerous real-life case stud- remark to the US Congress in 1973 that “any- lic-spirited economic behavior”. What Shiller ies, ranging from bimetallism (an old-fash- one who believes exponential growth can go seems to be saying is this: when ordinary ioned form of money) to bitcoin (a brand-new on forever in a finite world is either a madman human sentiment runs counter to the prevail- one), and from the Great Depression of the or an economist”. ing logic of capitalism, the state must override 1930s to the Great Recession of recent years. Shiller is clearly not a madman. But in the it. It is a deeply suspect, potentially dangerous Along the way, his anecdotes form a fascinat- course of an otherwise fascinating exploration conclusion. But it, too, demonstrates just how ing subscript. A convincing case is made, for pervasive narrative is. instance, that fears of a ‘singularity’ — a point of “It’s troubling, of course, Ultimately, Narrative Economics is an no return arising from technological advances eloquent and accessible exposition of a — are perennial. He notes numerous viral out- to be reminded that the seductive idea. It’s a particularly compelling bursts of this meme (associated with cotton rewards for creativity are hypothesis for Britain, a country still reeling mills, electricity and computers, for instance) often mislocated.” from a public referendum whose outcome was dating back to the nineteenth century. Today’s determined by viral confabulations of the most apocalyptic anxieties about a robot takeover pernicious kind. We are all “tellers of stories are nothing new and should not be heeded, of the power of story, he never once acknowl- and makers of poems”. But neither economists Shiller seems to imply. How that will turn out edges that eternal growth is itself just a nar- nor politicians can claim moral authority over remains to be seen. rative. He notes that the logic of relentless narrative truth. We must all choose carefully We learn that the mechanism through which expansion conflicts with the logic of human which stories we live by. a memorable turn of phrase goes viral can be anxiety. But he assumes that it is people who described as a form of contagion, mirroring are at fault. Narratives can have clear, moral Tim Jackson is director of the Centre for the models from epidemiology. But we are also and prudential foundations, it seems, but they Understanding of Sustainable Prosperity at persuaded that viral success depends inher- might still be cast as irrational. the University of Surrey in Guildford, UK, and ently on the messenger. Few remember that the Indeed, for Shiller, that memorable speech author of Prosperity without Growth. phrase “the only thing we have to fear is fear on the “fear of fear” shows government e-mail: [email protected] itself”, immortalized by US president Franklin D. Roosevelt during the Great Depression, was first uttered years earlier by economist Irving Fisher. It’s troubling, of course, to be reminded that the rewards for creativity are often misallocated Testosterone chronicles: — particularly in today’s plagiaristic world of social media, with its immense powers of nar- rative acceleration. But for me, this particular truths and tall tales example raised a deeper concern. Fear is a rational response from people whose livelihoods are under existential threat. So A book on the hormone dissects fact from fake and why would a president inveigh against it? The answer is that Roosevelt was painfully aware questions interpretations. By Randi Hutter Epstein of the implications of fear. He was addressing what the economist John Maynard Keynes (borrowing from another long-forgotten crea- n 1 June 1889, renowned neurologist sociomedical scientist Rebecca Jordan-Young tive) called the “paradox of thrift”: the tendency Charles-Édouard Brown-Séquard did not write Testosterone to rehash familiar of ordinary people to curtail their consumption shocked his colleagues. Speaking tales of wacky hormone experiments of yore, in the face of economic uncertainty, and put at the Paris Society of Biology, the although this is one of a few that they include. their money into savings instead. 72-year-old announced that a slurry Their contention is that many testosterone Such behaviour is sensible, admirable even, Omade from the ground testicles of guinea pigs researchers — then and now, and intention- at the individual level. Perhaps it is so at the and dogs (injected under his skin ten times in ally or not — interpret data with blinkers on. planetary level, too: lower consumption might three weeks) made him stronger. He also noted When the facts do not fit the paradigm, the benefit the environment. But economics has a that his “jet of urine” lengthened by 25%. authors argue, findings are moulded into problem with it. As people spend less, demand is Brown-Séquard was ridiculed by his peers flawed dogma. Karkazis and Jordan-Young suppressed, prolonging the recession. The same throughout Europe for disseminating results strive to comprehend how scientific practice thing happened after the 2007–08 crisis. The with no scientific basis and promoting quack paradox of thrift was the foundation for Keynes’s youth-enhancing ‘cures’. Yet the bizarre elixir Testosterone: most famous proposal: that governments pro- found favour with members of the public An Unauthorized vide stimulus that could return the economy in the United States, United Kingdom and Biography Rebecca M. Jordan- to growth when people would not. This was the Europe — at least among men eager to recap- Young, Katrina rationale for Roosevelt’s New Deal package of ture youthful sexual prowess. As the engaging Karkazis. reforms, and the inspiration for the proposed book Testosterone explains, Brown-Séquard’s Harvard University US legislation called the Green New Deal. testimonial helped to shape future studies that Press (2019) Keynes was a pragmatist; his prescriptions linked the hormone to alleged ‘manliness’. were a response to the diseases of the day. But Anthropologist Katrina Karkazis and 474 | Nature | Vol 574 | 24 October 2019 ©2019 Spri nger Nature Li mited. All ri ghts reserved. ©2019 Spri nger Nature Li mited. All ri ghts reserved. SIDNEY MOULDS/SPL SIDNEY Polarized-light micrograph of crystals of testosterone. around testosterone unfolds, and explore how precursor, DHEA, have a role in the maturation risk-taking through “weirdly narrow and also the results “circulate and morph in the world”. of ovarian cells; DHEA might boost fertility wildly divergent” behaviours, such as riding a Today, the biochemistry of this steroid hor- directly or as a mediator of oestrogen produc- motorcycle without a helmet. They cite a team mone is well known, from its daily fluctuations tion. There are chapters focusing on traits often that surveyed business students about their to its synthesis from cholesterol and occasional assumed to be associated with testosterone, entrepreneurial experience and used a saliva conversion to oestradiol, a form of oestrogen. such as athleticism. The authors also scrutinize sample to gauge their testosterone levels4. On Testosterone is known to restore sex drive the brouhaha surrounding a small psychology the basis of these dubious data, the investiga- and muscle tone among men with ailments study1 claiming that holding particular poses tors concluded that those who had the highest that reduce levels of the hormone, such as boosts testosterone production. There is a levels, coupled with family business experi- pituitary tumours. During puberty, a surge of section on parenting, thanks to studies that ence, were the most entrepreneurial. testosterone in young men typically leads to created a fleeting media buzz by claiming that When it comes to testosterone and aggres- enlargement of the muscles, penis, testes and new fathers’ testosterone plummets when sion, the authors say that some of the most rigor- prostate gland, and the emergence of second- they change nappies and do other nurturing ous studies (double-blind, placebo-controlled) ary sex characteristics. In women, testosterone chores2,3. And the authors discuss athletes who show no connection. What’s more, they write excreted by the adrenal glands and ovaries is take testosterone to boost their abilities. that even the investigators of studies that tie generally important for ovarian function and They do not dispute that injections, gels testosterone to violence acknowledge that the bone strength. or patches that send testosterone levels sky- link is inconsistent and weak. Yet the idea that Like pathologists doing a post mortem, rocketing above the norm build muscles when testosterone drives violence remains widely Karkazis and Jordan-Young dissect the remains coupled with intense training. But they are accepted and “grossly overblown”. of a selection of studies. They parse statistics sceptical about whether the hormone makes By setting the record straight, the authors and the cultural context that prompted the a large difference for every athlete. Some build on their past record. Jordan-Young research and influenced how the data were studies, they write, have found a correlation explored the evidence for putative neuro- analysed. (Full disclosure: I have served on a between high natural testosterone levels and logical sex differences in the 2011 book Brain history of medicine panel with Karkazis and, as speed and power; others show tenuous or no Storm; Karkazis demolished preconceptions medical authors writing about endocrinology, links.