Social play in primates

Anim. Behav., 1979, 27, 963-965

BOOK REVIEWS The World's Cats . Volume 3, Number 2 : Contributions to Biology, Ecology, Behavior and Evolution . Volume 3, Number 3 : Contributionss to Breeding Biology, Behavior and Husbandry. Edited by RANDALL L . EATON. Seattle, Wash. : Carnivore Research Institute, Burke Museum (1976, 1977) . Pp. vi + 179, 144 . The world's cats exemplify evolution of behavioural and ecological diversity within tight morphological constraints . As the papers in these volumes indicate, the basically conservative felid body plan allows considerable ecological variation as a result of differences in size and behaviour. Fells margarita, the sand cat, is a tiny (ca . 3 kg) Old World desert dweller . A dense mat of long hair on the soles of the sand cat's feet may improve traction or even tactile reception on a sandy substrate, and the sand cat's large external ears and grossly enlarged tympanic bullae serve to receive and to amplify sounds and soil vibrations (Hemmer, World's Cats 3 (3)) . Felis(Leopardus) wiedii, the margay, is a semi-arboreal Neotropical felid . The margay has elaborate morphological and behavioural adaptations for climbing and manoeuvring in three dimensions . Margays have a mobile ankle joint allowing up to 180' supination . They descend vertical supports head-first, can jump 2. 5 m vertically from a standing position and 3 . 5 m horizontally, remain highly playful throughout life in confinement, and exhibit unusual problem-solving ability (Petersen, World's Cats 3(2) and 3(3)). Margays' large brains, reduced litter size and slow development (Hemmer, World's Cats 3(2)) represent a probable instance of mammalian neoteny outside the order Primates (Fagen, R . and Wiley, K . Carnivore, 1, 72-81, 1978) . The sand cat and the margay are only two of the eight cat species covered by full-length original papers presented in these two excellent volumes . Other species treated in depth include Acinonyx jubatus (cheetah), Fells nigripes (blackfooted cat), Panthera leo (lion), Panthera pardus (leopard), and Panthera uncia (snow leopard) . The papers represent a balance between studies of free-ranging and of captive cats as well as a good blend of behaviour, ecology, morphology, and physiology . Especially noteworthy is the wealth of important new information on the smaller cats. In addition, excellent review articles treat fossil history, cytogenetics, sociality, gestation and post-natal development, diet, disease, and management . The editor's two theoretical contributions are among the most interesting of these reviews . Eaton's central argument, based on earlier work by Kleiman and Eisenberg, that felid sociality probably began with association of females, probably mother and daughter(s), is of renewed interest now that several independent field studies (e .g. J. Laundre. Anim. Behav., 25, 990, 1977) have demonstrated that free-ranging domestic cats frequently form enduring social groups organized along maternal lines of descent . The supposedly solitary and aloof domestic cat proves to be not so solitary, after all . The Felidae may hold additional surprises for students of behavioural evolution . These volumes help focus attention on a carnivore family that, now as ever, critically needs additional conservation efforts and scientific study . It is hoped that the new journal Carnivore, edited by Dr . Eaton as a successor to The World's Cats, will continue the tradition of excellence in feline biology established by these volumes . I highly recommend these two volumes of The World's Cats to students of behaviour, particularly of social

behaviour, and to ethologists and sociobiologists interested in mammalian behavioural development and evolution . ROBERT M . FAGEN

School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 . Social Play in Primates. Edited by EUCLID O . SMITH . New York, San Fransisco, London : Academic Press (1978) . Pp . xii + 324. Price $ 18 . 00, 11 . 70 . Because rigorous biological theory on animal play is conceptually and technically difficult to formulate and to test, tight hypothetico-deductive analyses of play tend to be scarce . Instead, descriptions of play are made for their own sake, verbal analyses of play are often confusing, and play itself remains poorly understood . Under these circumstances, various perspectives persist . Smith's edited collection of papers from an Animal Behavior Society symposium is a case in point . These contrasting approaches to primate play range from descriptive mathematics and statistics through social biology and ethology to more traditional and less formal approaches based on such psychological and sociological concepts as arousal, cohesion, and group adaptation . Smith restricts his editorial commentary on these papers to a brief but thoughtful preface . His own chapter, entitled `A historical view on the study of play : statement of the problem', cites important distinctions between structural and functional approaches, and between different types and levels of explanation, that informatively highlight and contrast the different approaches to play represented in the volume . The papers in this work represent ethological, behavioural-physiological, psychological, or social biological points of view . In addition to Donald Symons's important essay on the concept of behavioural function in play research, two other papers held this reviewer's interest . Play between non-human adults is seldom discussed at any length in the literature, and Breuggeman's ethological contextual analysis of play in adult rhesus monkeys of both sexes is a welcome contribution on this topic . The author's theoretical discussion neglects the obvious point that enduring effects of regular physical exercise and varied, non-aversive sensory stimulation could benefit adult monkeys . If so (and additional arguments are necessary to justify why this should be so in an evolutionary sense), play should decrease but not necessarily disappear with age, as I demonstrated some years ago using a theoretical model (R . M. Fagen . Am. Nat ., 111, 395-414, 1976) . However, an even more interesting point made by Breuggeman's study is that play can function in social manipulation in adult rhesus and therefore, presumably, in infants and juveniles as well . Maple & Zucker's description of play in captive great apes emphasizes orang-utan behaviour . The high frequency, complexity, and variety of play observed in captive orangs contrasts strikingly with early field reports that orangs play little if at all . Experiments by Maple & Zucker on interspecific (orang-chimpanzee) play demonstrate that these animals' play-signals are mutually intelligible and that heterospecific play can go on despite species differences in anatomy and play style . The ways in which young apes of different species overcome anatomical and behavioural differences and achieve stable play relationships are an especially interesting 963



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aspect of this paper . This unnatural combination of partners serves as an interesting experiment indicating kinds of adjustments that could also occur in more subtle ways in conspecific play. Smith & Fraser define play objectively and quantitatively using multivariate analysis techniques . Bramblett applies regression analysis to quantitative measures of play . Candland et al. offer fascinating descriptions of captive Japanese macaques constructing a swing and playing on it . Baldwin & Baldwin attempt a biologically unsatisfactory stimulus-response, reinforcement, arousal analysis of play . A very weak discussion of possible group-adaptive functions of play by Poirier et al . misses the crucial point that a behaviour may well benefit a group although it was selected because those individuals performing it left more surviving offspring . In fact, many social behaviours, including play, might benefit a group but would probably be counterselected at the individual level in any simple formal model . Poirier et al ., like Loy et al. in another paper in the same volume, misleadingly claim to employ an 'evolutionary perspective' (p . 144) or to employ 'sociobiological theory' (p . 72), while in fact these papers reveal ignorance of evolution and sociobiology. For example, Loy et al . separated all sibling pairs in order to perform a 'controlled' gonadectomy experiment on play. Were these authors at all familiar with sociobiological theory, they would have been aware that theory predicts, and that observations confirm, preferential play relationships among kin, especially siblings . Sib separation into experimental and control groups is therefore a potential confounding factor in this experiment . To make matters worse, Loy et al . incorrectly describe their analysis as 'sociobiological theory' . Ignoring the survivorship, growth, time, and energy costs of play in juveniles, this seriously flawed analysis likewise fails to recognize the obvious possibility that potential play partners, particularly older animals and nonkin, could be selected to resist play solicitation. The work includes a single contribution on human play, 'A longitudinal study of social play in Synanon/ peer-reared children' (Hamer & Missakian) . This study of effects of child-rearing practices on social play is flawed by lack of an appropriate control group . By editing this volume, Smith has made an interesting and welcome contribution to existing literature on primate play. The volume successfully conveys a variety of points of view. It is generally free of typographical errors, it includes a serviceable index, and it is readable . Most papers included would be of interest only to specialists . However, contributions by Symons, by Breuggeman, and by Maple & Zucker are valuable in a broader context . Symons's paper in particular should be required reading for all primatologists . Even if the sole reason for the publication of Social Play in Primates had been to make this paper available, that justification would be sufficient . ROBERT M . FAGEN

School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104 . Caste and Ecology in the Social Insects . By G . F. OSTER & E . O . WnsoN . Princeton : Princeton University Press (1978). Pp . xv + 352 . Price $20.00 cloth ; $8 .95 paper . As number 12 in a series of books on population ecology, this is not concerned with the morphogenesis of castes, nor with the ecology of social insects, but with the way polymorphism affects the efficiency of societies and,

through this, their evolutionary fitness. Most attention is given to the females of social Hymenoptera ; much less to termites. A set of algebraic models is constructed and their properties explored using mathematical methods largely derived from cybernetics and economics (58/240 references are to mathematical theory). The essential notion is that of optimization, and for balance the authors commendably conclude the book with a criticism of this approach and a list of unsolved problems . A brief list of subjects treated goes as follows : reproductive strategies, sexual investment, male parentage (whether from the queen or the worker), resource and caste distribution functions, efficient caste ratios (including situations of inter-colony competition), task diversity in relation to caste number, and the virtue of using big workers as soldiers. Many analyses provide for environmental uncertainty . The doses of maths are given at two levels : in the text (difficult) and in appendices to each chapter (very difficult) . This is wise, but I think most biologists will still need a little help from their mathematical colleagues. A new and improved sex investment model is given that takes into account the difficult question of colonylevel selection and the fact that males arise from workers as well as from queens . There are several interesting consequences : one is that evolution toward the production of males either by queens or by workers is more likely than an intermediate condition ; I think this is now near to being verified. It is interesting, too, that where workers produce the males, both female castes 'agree' on the sexual investment that is best for them, though they both disagree with the colony, which 'requires' more males . Where queens produce both sexes there is conflict with the workers (who 'want' more females) but agreement with the colony . There is very little discussion of how these investment ratios might be achieved, and much modern work on the influence that queens have on worker brood-rearing in relation to gyne production (the authors use the rather quaint 'virgin queens' for gyne) and in relation to the nature of the eggs laid by workers (whether reproductive or trophic) is not even summarized . An odd feature of the book is the distinction made between an 'ergonomic' stage, when the population is growing almost exponentially, and a 'reproductive' stage, when the colony is reproducing and not growing so fast . If 'ergonomic' refers to the efficiency with which the collection and presentation of food to larvae is ordered, then this is an important aspect of all stages of colony development whether immature or not, and as such is of no diagnostic value . The authors show that not all population growth is of the bang-bang type ; in the case of perennial societies, for example, as long as energy gain is not increasing mixed strategies may occur . The analysis of optimal caste ratios (chapter 6) produces many interesting ideas : on how many castes are worthwhile, on the forces affecting caste proliferation, on the optimum size frequency distribution and the effect of uncertain environments on caste specialization . It concludes that the usefulness of a specialized caste depends on 'the presence of occasional, but severe, contingencies' . The chapter on caste in the service of foraging strategy (chapter 7) also gives some interesting analyses, including this time quite simple models of bee and ant foraging . It starts by outlining the techniques used in foraging by various social insects, considers caste and the evolution of foraging behaviour, discusses how to measure task efficiency, builds models of the foraging