what you see

to a secondary position the equally impor-tant role of processes occurring across time.These are manifest in historical contingen-cies that are known to affect macroecologicalpatterns such as body-size distributions (the‘temporal embedding problem’). Second,because macroecology is mostly concernedwith, although not limited to, the search forstatistical regularities, the analysis of pat-terns is usually restricted to particular taxafor which large amounts of data are available.To what extent does knowledge generated for a particular taxon extrapolate to commu-nities or assemblages of diverse organismsliving in the same habitat?

Although it is wise to start the study ofcomplex ecological systems in a simple way, Ithink macroecology should go beyond thistaxon-based approach to the study of theecological systems in which particular taxaare embedded. Resolution of this ‘bioticembedding problem’ requires more empha-sis on the empirical analysis of macroecolog-ical patterns across taxa within communitiesand less on compilation studies for particu-lar taxa.

Throughout the book, the authors cor-rectly point out that macroecology restsheavily on the use of the comparativemethodology — the description of patternsand the development and testing of hypothe-ses using information on the distributionand covariation of traits (such as abundanceand body size) across species. In this kind ofanalysis, species are not independent realiza-

tions but are linked to each other by sharedancestry, which raises the statistical problemof non-independence of data. The authorsacknowledge this, cautioning on the need toremove the potentially confounding effect ofshared ancestry by using phylogeneticallyindependent comparisons, which supposed-ly remove the phylogenetic component fromthe pattern.

This is a contentious issue, however, asthe phylogenetic history of taxa is not in-dependent of their ecology. To some extent,what we call history is the history of the ecological interactions between species and their environments, and that is reflectedin extinction and diversification patternsthrough time. When phylogenetic signals are removed from the data, their ecologicalcorrelates are also removed. Further, even ifwe could assume that ecology and phylogenyare independent, too much emphasis isplaced on removing potential phylogeneticeffects on patterns and too little on actuallyquantifying how much variance in the pattern is explained by phylogeny and why itis stronger in some groups or for some traitsthan others.

Macroecology is in essence a discipline ofsynthesis, whose main aim is the search forgeneral principles or natural laws underly-ing the seemingly endless variability of lifein its many forms of organization. Afterreading Gaston and Blackburn’s book, however, it is clear there is still a long way to go. Macroecology is becoming stuck in

contingent explanations for many of thelarge-scale patterns it addresses. However manageable this contingency could be,more effort should be directed to get beyond it.

The structure and function of present-day ecological systems can be regarded as theresults of the unfolding process that startedwith the biotic Big Bang that was the emergence of life on Earth. The task of theecologist is to disclose the hidden order andthe rules that govern this process of unfold-ing. Gaston and Blackburn’s book is animportant step along this path — an auth-oritative characterization of the status of this research programme in ecology, a thorough pattern-by-pattern analysis and aprovocative statement on what macroecolo-gy is and what we should expect from it. ■

Pablo A. Marquet is in the Department of Ecology,Universidad Católica de Chile, Casilla 114-D,Santiago, Chile.

What you see …Visual Disturbances followingGunshot Wounds of the Cortical Visual Areaby Tatsuji Inouye (translated by M. Glickstein & M. Fahle)Oxford University Press: 2000 (Germanoriginal published by Wilhelm Engelmann:1909). 101 pp. $25

Daniel L. Adams and Jonathan C. Horton

The cerebral cortex is divided into dozens ofareas, each devoted to processing some element in the human repertoire, such asvision, hearing, touch or movement. A basic principle of neuroscience is that many areas contain an orderly, topogra-phical representation of the function thatthey serve.

The first such map was made for the visual cortex by a brilliant young Japanese ophthalmologist, Tatsuji Inouye. On 8 February 1904, shortly after his graduationfrom Tokyo University, the Russo-Japanesewar erupted. Inouye’s duty was to assessvisual loss in Japanese soldiers followingbrain injury so that their pensions could beadjusted suitably. Dissatisfied with thismundane task, Inouye set out to discoverexactly how the visual world is represented in the brain. The resulting monograph was published in German in 1909. Unfortu-nately, only a handful of copies were printed,and Inouye left science soon afterwards topursue medicine. His seminal contributionwas lost, until Glickstein and Fahle providedthis translation of a photocopy of the original, which they had discovered in the

book reviews

482 NATURE | VOL 412 | 2 AUGUST 2001 | www.nature.com

A page from the sixth-century Byzantine CodexAniciae Julianae, the oldestilluminated copy of thewritings of Dioscorides,ancient botanist andpharmacognosist.

This is one of around500 botanical illustrations,covering 15 centuries, in thetrilingual book Ein GartenEden, which accompanies anexhibition of some of theAustrian National Library’sextensive collection.

The exhibition runs until31 October 2001 at theAustrian National Library inVienna.

Garden Eden: Masterpiecesof Botanical Book Illustrationby H. Walter Lack (available inEnglish, German and French;Austrian National Library,US$39.99, £19.99, DM49.95,FF262.50).

The art of botany

© 2001 Macmillan Magazines Ltd

library of the Institute of Neurology in London.

To map the primary visual cortex, Inouyehad to overcome the problem posed by individual variation in head size and brain anatomy. This variability still dogs researchers today, especially those who use functional imaging techniques. Inouye’ssolution was to compile an average headmodel by measuring cranial landmarksusing a stereotactic instrument he in-vented called a cranio-coordinometer.Cadaver brains, cut sagittally, were photo-graphed and projected onto the head model to establish the coordinates of the calcarine fissure, which contains the pri-mary visual cortex.

The map was constructed by examining28 soldiers (selected from 80,000 wounded)who had suffered bullet wounds to the occipital lobe. The site of brain damage wascorrelated with the defect in the visual fieldto compile a retinotopic map — the ‘projection’ of the retina on the visual cortex.The Russians used a high-velocity rifle, theMosin–Nagant Model 91, that fired a 7.62-mm hard-jacketed bullet which pierced theskull without shattering it. It left tidyentrance and exit wounds, along a straighttrajectory, that could be measured using atape measure and translated onto the headmodel to plot the swath of destructionthrough the visual cortex.

Inouye showed an innovative flair andanalytical rigour that were absent in his contemporaries. Among many insightfulobservations, his study contained the firstaccurate description of the arrangement ofthe visual field map in the primary visual

cortex. The fovea was placed correctly at theoccipital pole, and the peripheral field at theanterior end of the calcarine sulcus. Theupper and lower visual quadrants weremapped onto the lower and upper calcarinebanks, respectively. Inouye illustrated theretinotopic map as a quarter-sphere, distort-ed into the shape of a trapezoid and projectedonto the surface of the visual cortex. Hebelieved that the distortion followed a mathematical function defined as the ‘area-true representation’.

His map magnified the most central,foveal portion of the visual field. Selectivemagnification of maps is a common themein the cerebral cortex. For example, in thesomatosensory cortex, which receives tactileinformation from the surface of the body, the fingers are represented by more brain tissue than the arm, although they are smaller in surface area. Inouye also recog-nized that the occipital lobe contains neighbouring visual areas, with less precisetopographic maps.

Credit for first describing the retinotopicmap in the human brain is often mistakenlygiven to a British medical officer, GordonHolmes, who performed a similar study during the First World War. It is unfortunatethat war has often been the instrument of scientific progress. In his foreword, Inouyewrote: “The hardship and ferocity of the lastwar led me to publish these observations.The awfulness and horror of the experience,of which those who did not take part cannothave the slightest appreciation, at the sametime raised the hope in me and in all other physicians that in the future, war may,if possible, be prevented.” Tragically, as

Inouye wrote these words, the world stood on the brink of the bloodiest centuryin history. ■

Daniel L. Adams and Jonathan C. Horton are in the Department of Ophthalmology, University of California at San Francisco, 10 Kirkham Street, San Francisco, California 94143-0730, USA.

Supersymmetricalphysics The Quantum Theory of Fields:Volume III. Supersymmetryby Steven WeinbergCambridge University Press: 2000. 419 pp.£32.50, $49.95

Hans Peter Nilles

The concept of quantum field theory, which arose in the 1930s from the com-bining of quantum theory with special relativity, enables us to describe all knownphenomena of particle physics. The first two volumes of Steven Weinberg’s bookThe Quantum Theory of Fields explain thisbrilliantly and have by now become classictextbooks.

As these two volumes showed, sym-metries have had a crucial role throughoutthe development of quantum field theory.They allow a simpler formulation of thesetheories and lead to the appearance of conservation laws for physical quantities.The rotational invariance in three-dimen-sional space leads, for example, to the con-servation of angular momentum, and theorigin of conserved electric charge can befound in a symmetry that transforms thephase of the electron wavefunction. Some-times new symmetries have been discoveredby direct experimental observation; some-times their presence has been imposed on physicists by demands for mathematicalconsistency and elegance. A cornerstone ofthe present-day ‘standard model of particlephysics’ is the concept of gauge symmetry,which is used to describe electromagneticinteractions as well as the weak and strongnuclear forces.

Weinberg’s third volume in the series,entitled Supersymmetry, describes a symme-try that was discovered as a mathematicalcuriosity some 30 years ago. Although thereis no convincing evidence yet for its existencein nature, supersymmetry is one of the mostdiscussed themes in modern particlephysics. Intrigued by the uniqueness andtheoretical beauty of this symmetry, practi-tioners in the field are confident that interestwill continue in the coming years and evendecades.

Supersymmetry relates two differentclasses of particles: bosons (which have

book reviews

NATURE | VOL 412 | 2 AUGUST 2001 | www.nature.com 483

The cranio-coordinometer (left), used to plot the trajectory of bullets through the head (right).

© 2001 Macmillan Magazines Ltd