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stronger than humans, but deduces from hisanthropocentric items that human evolu-tion has occurred at about 10 times the rateof ape and monkey evolution.

How easy it would be to argue the con-trary from the chimpanzee point of view:that we are a most retrograde species whohave lost our body hair, facility in climbingtrees, female sexual swellings and numerousother primate assets. A more neutraldescription would merely state that we areadapted to a way of life very different fromthe ancestral one, and that small changes atthe molecular-genetic level can obviouslyresult in major phenotypic and behaviouralmodifications.

The mystery of the big human brain andwhat goes on inside it intrigues Wills, as it hasfascinated so many others.

The last few chapters, some of the best inthis book, deal with the genetic aspects ofdiseases such as narcolepsy, attention-deficithyperactivity disorder, schizophrenia,Alzheimer’s disease and the much-debatedfactors in IQ. He speculates that rapid gener-ational changes in microsatellite DNA —which are known to account for several neu-rological diseases, such as Huntington’schorea — could be a mechanism for intellec-tual improvement. In Wills’s opinion, ourgrandchildren will surely be smarter than us,and within a few generations Einsteins andMozarts will be commonplace.

These optimistic exegeses, while notwithout interest, illuminate by omissionhow little we understand about the molecu-lar, functional and adaptive factors that have

inflated the human cranium and its contentsthreefold over the past five million years.

In his last chapter, “Our evolutionaryfuture”, Wills unhesitatingly predicts an evenbigger-brained advent that will carry usbeyond the Solar System to planets of otherstars. I admire the courage of someone whocan make such projections for a society thatcannot predict the next election result or theweather next week.

Are we still evolving? This is the questionWills asks at the beginning and end of his vol-ume, and at many points in between. Theanswer is, of course, that we are: as are chimp-anzees, gorillas, orang-utans, crocodiles andbacteria. Are we really evolving much fasterthan those other organisms? Not at the mole-cular level, according to present evidence.Even bacteria, the oldest and most ‘primitive’forms of life, show a degree of flexibility intheir ability to survive and become resistantto our most potent antibiotics that our ownspecies has yet to prove it can match.

In Darwin’s concept of evolution, thedirection of evolutionary change is unpre-dictable, dependent as it is on changing con-ditions and the vagaries of natural selection.Wills’s confidence as to which evolutionaryfeatures are good or bad, superior or inferior,faster or slower, conveys perhaps a hint ofPromethean hubris.

For the future of the species, let’s hopethat our grandchildren will, as Wills predicts,be smarter than we are.Adrienne Zihlman is in the Department ofAnthropology, University of California, SantaCruz, California 95064, USA.

A most upliftingcareerOut of the Crater: Chronicles of aVolcanologistby Richard V. Fisher Princeton University Press: 1999. 178 pp.$24.95, £16.95

Steve Sparks

The life of an academic field geologist, espe-cially one interested in volcanoes, has consid-erable attractions. Pleasures to be foundinclude visiting beautiful and sometimesremote parts of the world, and enjoying thecompanionship of like-minded colleagues,the inevitable adventures and mishaps, andthe intellectual challenges of interpreting thetantalizing clues nature provides on how theEarth works. Richard Fisher, professor ofgeology at the University of California, SantaBarbara, is among the foremost volcanic geol-ogists of the second half of this century. Out ofthe Crater is essentially his reminiscences.

The book makes interesting and entertain-ing reading because of the richness of Fisher’sexperiences and the spectacular nature of hissubject. Each short chapter includes anec-dotes and descriptions of the parts of theworld he has visited, occasional explanationsabout the science of volcanology and someinsights into how he developed his scientificideas. The reader will be taken to some of theworld’s great volcanoes — such as El Chichónin Mexico, Vesuvius and Mount St Helens —and to diverse cultures: the American West,Argentina and China.

Fisher’s unique formative experience waswithin the context of a remarkable episode intwentieth-century history. In 1946, at 17 yearsold, he was stationed in the army at Los Alam-os and volunteered to go to Bikini atoll, wherehe observed the atomic bomb tests. Hisdescriptions of the Bikini tests are fascinating,and highlight the military authorities’ almostcomplete lack of understanding of the lethaland long-term effects of radioactivity. Toswim in the ocean at Bikini atoll a few daysafter the test now seems incredible.

What made the Bikini experience soimportant for Fisher’s later scientific achieve-ments was seeing the base surge phenomenon— the cloud of radioactive dust and waterdroplets that spreads radially along theground from the base of an atomic explosion.Fisher’s significant contribution to vol-canological science has been the elucidationof the geology of pyroclastic density currents,a term that encompasses volcanic base surges,pyroclastic flows and volcanic blasts like thatof Mount St Helens in 1980.

When volcanic base surges were first rec-ognized, Fisher realized the significanceimmediately. The enigmatic sedimentarystructures in many pyroclastic sequences,

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This satellite image showsan unusual view of Mount StHelens and the area aroundit, 11 years after the 1980eruption. Winds of up to 440 kph flattened a widearea and lava fanned outfrom the volcano, leavingwhat is now a horseshoe-shaped crater, lower left,containing a lava dome 300 metres high. Faint tracesof green in the purple lavashow the regrowth ofvegetation, especially inprotected valleys. It is one ofthe many dramaticcomputer-generated digitalimages, obtained by satellitesensing systems, in Americafrom Space by Thomas B.Allen (Firefly, $29.95).

Blastfrom thepast

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which were commonly dismissed as rework-ing, were primary features of volcanic flow.

Fisher generously acknowledges that thecredit for seeing the link between the atomicbase surges and volcanic phenomena belongsto Adrian Richards, who briefly noted the sim-ilarities in 1959, and to Jim Moore of the USGeological Survey, who developed the insightin detail. However, it was principally Fisherwho pioneered the systematic documentationand interpretation of the deposits of basesurges with colleagues and students such asAaron Waters, Hans Schminche and GrantHeiken. This exciting and important period involcanic geology is described with the insightsinto the twists and turns of original discoverythat are usually missing from scientific papers.

Later in the book, Fisher also describes incharacteristically modest fashion his impor-tant discoveries and ideas about pyroclasticprocesses such as ash-cloud surges, flow trans-formations and the expanded character ofsome pyroclastic flows.

Volcanology can be a dangerous profes-sion. The most poignant part of the book con-cerns the deaths of two outstanding youngAmerican scientists by volcanoes just as theircareers were blossoming. When Mount StHelens started to erupt in 1980, Harry Glickenwas stationed at the Coldwater II observationpost, six miles north of the volcano. Glicken

had a meeting with Fisher on 18 May to discusshis career and so David Johnston took over hisduty. The catastrophic eruption of that daykilled Johnston. Eleven years later, Glickenwas killed by a pyroclastic flow on MountUnzen in Japan along with the film-makersKatia and Maurice Kraft and many journalists.

Pyroclastic density currents are the mostlethal of volcanic phenomena. As this bookreminds the reader, advances in understand-ing the geology of these deposits (in whichFisher himself has played a leading role) haveestablished the criteria for identifying them —which is an essential part of volcanic hazardand mitigation work.

Fisher is a good writer and mixes tales of histravels, science and personal anecdotes well.The book is entertaining and an easy read.Geologists will enjoy the book because theywill be reminded of their own escapades.Young people contemplating a geologicalcareer will surely also be seduced by the idea ofa slightly anarchic life in remote and beautifulparts of the world. Fisher has clearly beenmotivated by the wonder of nature and thefundamental desire to understand its myster-ies that drives many successful natural scien-tists. Perhaps the only regret is that the book isnot a bit longer.Steve Sparks is at the Chiron Corporation, D-207Q, Emeryville, California 94608, USA.

Speaking in tonguesThe Neurolinguistics of Bilingualism:An Introductionby Franco FabbroTaylor & Francis: 1999. 255 pp. £39.95

Risto Näätänen and Teija Kujala

The past few decades have seen our exposureto multiple languages continuously increas-ing. In this sense, Franco Fabbro’s Neurolin-guistics of Bilingualism, dealing with the rep-resentation and processing of multiple lan-guages in the brain, meets an urgent need.Another major factor underlining theimportance of this research field is that bilin-gualism is by no means unusual. If we defineit in the broad sense — to include not onlypeople who from an early age have spokentwo or more languages, but also those whomaster a foreign language to a certain extentor a language in more than one dialect —then bilingualism covers more than half ofthe world’s population.

The main message of the book is howlesions in various parts of the brain affect thecomprehension and production of languages.Important questions are addressed, such aswhat happens to the native language com-pared with those acquired later in life whencertain parts of the brain are damaged, or, ifthese languages are lost, which of them recov-ers first or to the greatest extent. The casesdescribed elucidate not only bilingualism, butalso, more generally, the fascinating complex-ity of human cognitive brain functions.

A great strength of the book is that it isorganized in an extremely reader-friendlyway. It starts with a general introduction onwhat language is and how the acousticalanalysis and production of speech take place.This is followed by an introduction to thefunctional anatomy of the brain. The readeris also briefly introduced to technologies andmeans of studying cognitive brain functionsand assessing language-related dysfunc-tions. This introductory part makes the restof the book comprehensible to readers whodo not have a solid knowledge of the brain’sfunctional neuroanatomy. Without such anintroduction, the main part of the book,which attempts to explain bilingualism fromobservations on patients with brain lesionscausing various forms of aphasia and dys-phasia, might be hard for readers outside thefield of neuroscience to understand.

The case reports — describing how lan-guage functions can be affected by a brainlesion, and how these functions are recovered— are interesting and very helpful for under-standing how multiple languages are repre-sented in the brain. But this emphasis onbrain lesions makes the book somewhat one-sided and is problematic for several reasons.

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Cats’ Paws and Catapults: MechanicalWorlds of Nature and Peopleby Steven VogelPenguin, £8.99“Vogel’s book has been written to be enjoyed. …It is full of ideas and well-explained principlesthat will bring new understanding of everydaythings both to non-scientists and scientists alike”.R. McNeill Alexander, Nature 392, 881 (1998).

The Number Sense: How The MindCreates Mathematicsby Stanislas DehaenePenguin, £8.99 “Our ability to use numbers is as much afundamental aspect of what makes us human asis our ability to use language. This book providesan excellent introduction to how this ability isorganized in our mathematical brain.” BrianButterworth, Nature 391, 856 (1998).

Volcanoes: Crucibles of Changeby Richard V. Fisher, Grant Heiken and Jeffrey B. HulenPrinceton University Press, $19.95, £14.95

Twins And What They Tell Us AboutWho We Areby Lawrence WrightWiley, £14.95 “As a measured analysis of a complex andcontroversial field, it is not very good... The book

is essentially a collection of the sometimesdivergent views of the field’s main players aboutthe significance of genes.” John Galloway, Nature392, 34–35 (1998).

Why People Believe Weird Things:Pseudoscience, Superstition andOther Confusions of Our Timeby Michael Shermer, with a foreword by StephenJay GouldW. H. Freeman, £10.95, $14.95“Shermer refuses to engage deeply with whybeliefs are held. … In the Middle Ages it took therack and the thumbscrew to make people confessthat their father drank babies’ blood. Now, acouple of sessions in an air-conditionedpsychotherapist’s office seems to suffice. Whatneeds explaining is how we have become suchwimps.” John C. Marshall, Nature 389, 29 (1997).

Rethinking Visual Anthropologyedited by Marcus Banks and Howard MorphyYale University Press, $18, £12.95

Space and The American Imaginationby Howard E. McCurdySmithsonian Institution Press, $17.95, £10.95“McCurdy, an acknowledged authority on theUS space programme … tells a richly detailedand persuasively balanced story that explains theparadox of manned spaceflight.” Alex Roland,Nature 392, 143–145 (1998).

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