28 April 2012 | NewScientist | 49

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A vision of victualsThe Omnivorous Mind: Our evolving relationship with food by John S. Allen, Harvard University Press, £19.95/$25.95

Reviewed by Catherine de Lange

NO SPECIES has a more complex relationship with food than we do. There are few edible items that, somewhere in the world, humans do

not eat. The evolutionary benefits of a diverse diet are obvious. Yet unlike other omnivores, our diets are tightly interwoven into the fabric of our society. There are

A brief history of EarthThe Story of Earth: The first 4.5 billion years, from stardust to living planet by Robert M. Hazen, Viking Press, £17.50/$27.95

Reviewed by Michael Marshall

AT ONLY around 300 pages long, The Story of Earth ought to be too short for its subject. But mineralogist Robert M. Hazen of the Carnegie

Institution for Science in Washington DC does a wonderful job of condensing a mountain of technical information into a gripping, well-told story – without

The clock withinUnderstanding what keeps us ticking could benefit us all, finds Richard Wiseman

When it comes to sleep, why are some people larks and others owls?

Internal Time: Chronotypes, social jet lag, and why you’re so tired by Till Roenneberg, Harvard University Press, £19.95/$26.95

IN 1729, French astronomer Jean-Jacques d’Ortous de Mairan carried out a simple, but ingenious, experiment. De Mairan had

noticed that the mimosa plant opened its leaves during the day and closed them at night. To find out whether it was responding to sunlight, he shut the plant in a cupboard for several days and sneakily observed its behaviour. To de Mairan’s amazement, the plant continued to open and close its leaves as normal. He concluded that it must contain some form of “internal clock”.

Scientists are now seeking the existence of similar mechanisms

in humans. Their work has included observations of the sleep patterns of volunteers cut off from the outside world, global surveys of the time people wake up, and animal studies looking for mechanisms that keep

perfectly palatable foods that some people will not eat, for example. Others have an aversion to food altogether. Where’s the evolutionary sense in that?

After a slow start, John S. Allen’s The Omnivorous Mind becomes an authoritative, if rather stoic, guide to the ways in which humans eat with their minds as much as their stomachs. This includes the relationship between food and memory, language and diets, and the importance of categorising foodstuffs.

Allen often strays far from the principle subject, so those hoping for a focus on food may lose interest. But anyone curious about the human condition will welcome the diversity. n

sacrificing any of the scientific uncertainties along the way.

Hazen caused a stir when he proposed that life was responsible for Earth’s incredibly rich diversity of minerals. By breaking down rocks and changing the composition of the oceans and air, his theory goes, life created crystals and ores that would never otherwise have appeared.

That is just part of the story told here, as Hazen sweeps from the initial assembly of Earth to the rise of complex life. His vivid descriptions of the early Earth’s tortured landscapes are a joy, as is his Carl Sagan-like gift for conveying the sheer age of our world and the vastness of space. A fantastic, stirring read. n

our circadian clocks ticking. In Internal Time, Till

Roenneberg, a chronobiologist at the Ludwig-Maximilians University in Munich, Germany, takes readers on a journey through this mysterious area of science. He explores why some people are larks and others owls, why jet lag can be so debilitating to travellers, and why teenagers struggle to get out of bed in the morning. Roenneberg also

examines how this work has important consequences for individuals and society: teenagers might be more productive if classes started later, for instance.

Most chapters follow the same format, with Roenneberg presenting a fictitious case-study as an introduction to the relevant research. One chapter, for example, takes readers on a visit to the year 2210 and the headquarters of the World Agency for Space Settlements, which has invited a chronobiologist to advise on how humans’ internal clocks might be affected by life on other planets. Roenneberg is a knowledgeable guide, with a talent for making difficult concepts clear and convincing. But these fictional parts often feel laboured and out of place.

Nonetheless, this is a fascinating introduction to an important topic, which will appeal to anyone who wishes to delve deep into the world of chronobiology, or simply wonders why they struggle to get a good night’s sleep. n

Richard Wiseman is a professor of psychology at the University of Hertfordshire, UK. His latest book is Paranormality (Macmillan, 2011)

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