BOOK REVIEWS 949

gram would not have yielded a more succinct description of the preferences. But that could still be done.

jUAN D. DEHUS Experimentelle Tierpsychologie, Psyehologisches Institut, Ruhr-Universitiit Bochum, Federal Republic of Germany.

The Explanation of Organic Diversity: the Comparative Method and Adaptations Jor Mating. By MARK PdDLEY. Oxford: Oxford University Press/Clarendon Press (1983). Pp. viii+272. Price s

i t is a truth insufficiently acknowledged, that the com- parative method provides the most effective tool available for explaining the diversity of life. Animals adapt to changing environments as evolution proceeds, but the niches available are limited. This means that the same adaptations are likely to evolve time and again as differ- ent taxa respond to similar selective pressures. Such evolutionary convergence results in repeated associations between the same morphological and behavioural traits. Bright coloration and distastefulness among insects is an example. Some adaptive explanations for the presence of particular traits predict certain correlations that other explanations would be hard put to accotmt for.

Used properly, the comparative raethod is powerful and incisive, but in the wrong hands it leads to a night- mare world of invalid inference. One of the main prob- lems about many applications of the method is a failure to identify independent evolutionary events. When we search for an association between bright coloration and distastefulness in insects, what should we use as our data points ? Obviously individuals are out because individuals of a species are the same. But a similar argument could be used for species, since congenerics tend to have the same methods for anti-predator defence. The answer is to identify single evolutionary origins of both bright coloration and distastefulness. It could be that some genera contain cryptic and conspicuous species as well as palatable and unpalatable species, whereas all the species belonging to other genera are identical on both measures. There is no single taxonomic level for analysing such data. Evolutionary change can have occurred at any time in the past, but taxonomic identity is not independent of time.

In an extremely hnportant contribution to the com- parative literature, Mark Ridley identifies tiffs problem and provides a method for dealing with it. His method is not altogether new, but his comprehensive treatment of it is unparalleled. He uses the cladistic technique of out- group analysis in a rather unconventional way. Sensible cladists use outgroup analysis for identifying phylo- genetic relationships. Ridley applies the technique to phylogenies that have been derived by other means. Variation is found at one taxonomic level, and then the outgroup is defined in order to identify the primitive state of the character. The key assumption used is parsimony (others might argue for maximum likelihood). It is all very well to describe a method, but it is quite another thing to apply it. Few would have such confidence in their method to apply it first, and without reservation, to a very difficult case. Yet Ridley does just that. In fact, he applies the method to two conceptually quite different cases.

The first and most comprehensive application is to pre-copulatory mate guarding. The hypothesis tested is that pre-copulatory mate guarding should be found only when females will become sexually receptive during a short, predictable interval. A model co-authored with

Alan Grafen provides the them'etical basis for the pre- diction. Ridley applies his method to the animal king- dom: not only to crustaceans or to amphibians but to everything. (Somehow, he manages to exclude pre- copulatory mate guarding in birds and mammals-- fur example, consorting in primates. I could not understand why, but he does. I, for one, am willing to forgive this oversight of some minor taxa for his detailed treatment of the Flabellifera which, incidentally, make no inde- pendent contribution to his test.) As with the application of any new method, there are numerous problems that the practitioner must meet head on. Ridley meets more than his fair share of them. But the problems are not insurmountable, although the literature review would be for the common mortal. Ridley wins the day, so does his hypothesis, and so does his method.

After pre-copulatory mate guarding we get homogamy (some would call it assortative mating but homogamy 'has priority, is shorter, is etymologically preferable, and more populist'. It will never catch on but he's right). The idea here is that larger males in a population tend to mate with larger females. This would be expected if larger females lay more eggs, larger males win fights against smaller nmles, and mating takes a long time. Fortunately for reader and author alike, the relevant literature is not so extensive. And the theory goes a long way towards explaining it.

My main worry about this book is that it will not get read. If that turns out to be the case, it will not be the author 's fault. Too many papers dealing with the com- parative method are fundamentally flawed, while those that claim methodological advances usually ignore the practicalities of their favoured approach. Mark Ridley presents a method (he would argue the method) and, after exposing many of its weakest assumptions (one important weakness that he does not discuss is the enormous amount of information lost when continuously variable characters are artificially dichotomized), he shows how it can be made to work. He is bold in Iris assertions, and those who wish to pursue comparative studies would be well-advised to read his book from cover to cover. For if they disagree with him, and I do not, they should understand why. If they agree with him, then they should probably be using the method them- selves.

PAUL H. HARVEY School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, U.K.

Advances in Analysis of Behaviour. Vol. 3, Biological Factors in Learning. Edited by MICHAEL D. ZEILER Pm'ER HAaZEM. Chichester, Sussex: John Wiley (1983). Pp. ix+410. Price s

The publication of this book 10 years after Constraints on Learning by Hinde & Hinde invites one to see it as a report on progress made in this area over the last decade. Of course, the phrase 'biological factors in learning' need not be interpreted in this way. It can encompass the dis- cussion by Maier and his seven co-authors of the neuro- physiology of learned helplessness, and the chapter by Terman showing how circadian rhythms can influence performance in the Skinner box in ways unsuspected by most experimenters. The chapter by Perkins, apart from its brief discussion of 'preparedness' is solely devoted to presenting a Skinnerian theory (that is, a theory that avoids postulating mechanisms) of conditioned perfor-

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mance and does seem somewhat out of place. The re- maining seven chapters, however, are concerned in one way or another with what one of them (by Timberlake) refers to as the fundamental division between the eco- logical and arbitrary approaches to learning. (Timberlake apologizes for these labels as most of the other authors do for their own alternatives--perhaps we should take up his suggestion of calling them the clean-shaven and bearded approaches.)

Three chapters present discussions of possibly 'specialized' forms of learning: Hoffman & Segal provide a useful review of Hoffman's work on imprinting; Logan supplies a comprehensive review of the diversity seen in song-learning among passerines; and Rovee-Coliier describes her work on operant conditioning in the human infant. Shettleworth puts work of this sort into context when, in her excellent introductory chapter, she argues that specialized functions need not be served by specia- 1/zed mechanisms and, on analysis, have often proved not to be. Imprinting (along with flavour aversion learning) is a case in point here; of song-learning Shettleworth points out that here the ways in which experience affects be- haviour are so remote from traditional paradigms for the study of learning as to have had little impact on theorizing about the topic, More generally, Shettleworth's message is that much of the strident tone of the early days of the debate over 'constraints on learning' had its roots in a failure to make a proper distinction between function and mechanism. Timberlake's 'fundamental division' is some- thing of a throwback, but progress is surely evident in Shettleworth's prediction of a 'rich and productive interplay' between biological considerations and tra- ditional analyses of learning.

Perhaps such an interplay can be discerned in the three remaining chapters of the book. Collier's analysis of the rat 's lever-pressing for food, attempts to marry notions from operant psychology with others from the ethological analysis of foraging, an interplay that Shettleworth picks out for special commendation. It may be premature, however, for psychologists and ethologists to congratulate themselves about this union. The linking of Skinnerian psychology with ethological foraging theory has long seemed to me a match made in heaven. Both partners are keen to provide descriptive, often mathematical, accounts of behaviour and both have eschewed theorizing about detailed, 'molecular' mech- anisms. The link between traditional (associative) learning theory and biological considerations may prove harder to forge. The chapter by Timberlake takes pains to demonstrate that the form of the conditioned response generated by using the presentation of another anflnal as the conditioned stimulus is not that predicted by current associative theories. And the elegant experimental analysis provided by Lohordo & Jacobs of avoidance learning in the rat, although it puts paid to any simple analysis in terms of constraints on learning, leaves learning theory with a number of outstanding prob- lems. But I suppose the learning theorist should be pleased that experiments based on 'biological' con- siderations have thrown up phenomena that are new grist for his theoretical mill, and we may hope that he will go on to develop new theories that will accommodate these phenomena as they have done others.

GEOFFREY HALL Department of Psychology, University of York, York Y01 5DD,

�9 U.K.

JPrimate Social Relationships: An Integrated Approach. Edited by ROBERT A. H~YOE. Oxford: Blaekwell (1983). Pp. xv+ 384. Price s hardback, s paperback.

Thanks to the diligence of both field and laboratory workers over the last 29 years we now have an enormous amount of detailed information on the social behaviom- of primates. The problem that faces us is how to cope with all this detail. For example, it has become clear that each individual rhesus monkey in a group differs in its be- haviour in inaportant ways from each of the other members in its group, and that each social group can differ in important ways from its neighbours. In the face of such individual variation, how can one begin to ex- tract general principles about primate social behaviour ? How can one progress beyond presenting the behaviour one observes as no more than a series of case histories ? Primate Social Relationships, edited by Robert Hinde, is the first book on primate social behaviour to make a major attempt to tackle this problem. It concentrates on three well-studied species, the rhesus monkey, Macaea mulatta, the savannah baboon, Papio eynoeephalus, and the vervet monkey, Cercopitheeus aethiops, and deals with fundamental problems such as the description of social behaviour, the analysis of individual differences in be- haviour, the changes in relationships that occur during infant development or at other times of social change, and so on.

The design of the book is unusual in that each chapter is written by several authors. Most start with a short, theoretical section by Hinde, followed by from one to several short contributions by different authors that amplify or illustrate the themes of the introductory section. For example, the chapter on the development and dynamics of relationships begins with a discussion by Hinde on the respective contributions that participants make to social relationships, and to changes in these relationships; on the role that primates' advanced cognitive abilities play in their relationships; and on the extent to which developmental changes in relationships can be described in terms of positive or negative feedback. The next section, also by Hinde, presents data illustrating the last of these points. There then follow case studies by five different authors on topics such as the differentiation of relationships among rhesus monkey infants (by Carol Barman), the acquisition of rank in rhesus monkeys (by Saroj Datta) and so on. This multi-authored arrangement could easily have been disastrous, but in fact the plan works extremely well. In almost all instances, the case studies genuinely exemplify the issues discussed in the introductory sections of the respective chapters, and what could have been a disjointed assortment of poorly- related articles, proves to be a well-integrated treatment of the major issues of primate social behaviour.

The book is full of interesting new information and insights, and not just about features such as dominance rank, kinship, age and sex that are well known to be important in primate social behaviour. John Colvin, for example, provides convincing data to show that ado- lescent male non-siblings can have two different kinds of relationship with each other, and that these in turn differ from the relationships that the adolescent males have with their brothers. Similarly, Barbara Smuts shows that female baboons have enduring relationships outside the period when they are sexually receptive with specific adult or subadult male 'special friends'. Saroj Datta shows that immature rhesus monkeys behave as if they know whom they 'ought ' to outrank in their group, even if they do not yet do so, and so on. It is possible, as