Arrirn . Behav., 1975, 23, 757-765 A COMPARISON OF AGGRESSIVE PLAY AND AGGRESSION IN FREELIVING BABOONS, PAPIO ANUBIS BY N . W . OWENS* Sub-department of Animal Behaviour, High Street, Madingley, Cambridge Abstract. A quantitative comparison is given of aggressive play and aggression in terms of the duration and type of movement patterns employed, and the relationships between individuals. The mean length of contact in play was greater than in aggression, whereas chases tended to be longer in adult male aggression than in play, Linear hierarchies describing the overall direction of interactions between individuals were divisible into two sorts, according to the frequency with which roles were reversed . The regions of the body bitten and the proportions in which six types of movement pattern were used were related to the type of hierarchy involved . The results are discussed with reference to the possible functions of social play in the development of movement patterns and individual relationships . This paper is a corollary to an earlier paper (Owens 1975) on social play behaviour in baboons . Almost all the social play observed in baboons consisted of agggressive movement patterns . Aggressive play was separated from true aggression by the criterion of threat, those interactions in which intense threat gestures were absent being classed as play. This distinction appeared from qualitative observations to have some reality in terms of the nature of the interactions that occurred . This paper describes quantitatively the differences and similarities between play and non-play aggression in relation to the duration and type of movement patterns employed, and the relationships between individuals . It has been claimed that play signals, such as the `play face' (Van Hooff 1967) communicate to other animals something about the nature of the behaviour that is to follow . This has been termed 'metacommunication' (Bateson 1955 ; Altmann 1962). Qualitative observations of play have suggested to many observers lackbeen of `seriousness' or function, and this ahas
establish individual relationships (Hall 1962 ; Harlow & Harlow 1965) . No previous studies have provided hard evidence, however, as to the types of relationship established in play, nor whether these may persist into adulthood . Methods The study was carried out in the Gombe Stream National Park, Tanzania, between January and November, 1970 and April and August, 1971 . The study area, the baboon troop, and the field methods employed have already been described (Owens 1975) . Attention was focussed on the relative frequency of occurrence of different movement patterns in play and aggression . Aggression was separated from aggressive play by the criterion that at least one of the participants showed gestures of intense threat . The following details of aggressive behaviour were recorded, using a portable tape-recorder and stop-watch, and later transcribing to a data sheet . (a) The length of contacts (comprising wrestling, sparring, mauling or biting) and the length of chases . A contact or chase was considered to have ended when the sequence was interrupted by a break of 1 s or more . (b) The movement patterns that occurred in each interaction . The following six patterns were recognized : (i) Wrestling : the participants roll and grapple together on the ground : usually accompanied by mutual biting . (ii) Sparring : the partners stand facing each other, grapple with the arms and hit one another about the head ; rolling on the ground not involved .
attributed to certain characteristics of the organization of play movement patterns (e .g. Lorenz 1956 ; Loizos 1966) . Few studies have compared quantitatively the nature of interactions in play and non-play to show exactly what these differences are (but see Bekoff in press ; Loizos 1967a) . Such studies are essential to an understanding of the causation and function of play. It has been suggested that through play, primates may develop motor skills (Loizos 1966 ; Jay Dolhinow & Bishop 1970) and *Present address : 39 Caernarvon Road, Norwich, Norfolk . 757
758
ANIMAL BEHAVIOUR, 23, 4
{iii) Mutual, biting : both partners bite the other. (iv) Mauling : interactions involving contact in which one partner is inactive throughout the sequence and is mauled by its partner . (v) Non-mutual biting : only one partner bites. (vi) Approach-withdrawal : comprises chasing or being chased. The first three movement pattern categories are `mutual' categories, i .e. each baboon is equally involved in the interaction . The second three categories are `non-mutual', i .e. one baboon has an active and the other a passive role. In addition, the parts bitten in young-young and adult female aggression were recorded concurrently . The body was arbitrarily divided into twenty anatomical regions, and a symbol used to denote each region for recording purposes. Separate observations were made of the parts bitten in play and adult male aggression. To record play biting, one playing animal was watched for one bout at a time . (Note that a play bout was defined as a sequence of play uninterrupted by a break of 1 s or more) . The identity of its play partners and all the parts that received bites from the target animal were noted, regardless of the length of time that each part was bitten . The procedure was then repeated for the next bout, though sometimes one or two intervening bouts would be missed . Six males and four females were observed, ranging in age between 12 and 45 months . The data for male biting comprised about 95 per cent male-male biting and 5 per cent malefemale biting . Data for females comprised about 95 per cent female-male biting and 5 per cent female-female biting . It was not possible to record the parts bitten in aggression between adult males directly, because biting was usually too fast and too brief to see . Instead, wounds received by adult males
(both flesh wounds and pieces of fur removed) were used as an indication of the regions bitten . It is most unlikely that such wounds would be inflicted other than by an adult male baboon . Other troop members did not bite adult males except in play, and only adult males had sufficiently long canines to give such wounds . It is possible that some of the wounds may have been inflicted during fights with predators, such as chimpanzees, but such fights were never observed to result in wounding, and were relatively very infrequent. Only one of the thirty-five wounds recorded was observed at the time it was inflicted, and the others were seen up to 2 weeks afterwards. Results The Length of Instances of Contact and Chasing in Play and Aggression The mean length of contacts was greater in male-male play than in female-female play and greater overall in play than aggression (P < 0 .001 in both cases ; d test ; Table I) . The length of contacts in play also showed more variance than in aggression, owing to the occurrence of some very long contacts (up to 60 s) in play. The mean length of chases was greater in adult male aggression than in any other category of aggression or play (P < 0 .001 ; d test) . The tendency towards shorter contacts in aggression than in play was probably a result of the participants' greater fear of one another in aggression . Similarly, the long chases characteristic of adult males were probably a reflection of their fear of engaging in physical contact with one another . Even during the brief fights that did occur, wounds were often inflicted with the canine teeth. In adult female aggression however, chases were relatively short because the aggressee tended to stop and present in submission to the aggressor, rather than attempt to escape. Play chases were shorter than those in
Table L The Length of Instances of Contact and Chasing in Play and Aggression Mean
Contact (s) SD
PLAY Male-male (5-37 months) Female-female (11-37 months)
7 .56 5 .57
8 .79 5 .64
AGGRESSION Young-young (5-60 months) Adult male-male (> 7 years) Adult female-female (> 5 years)
3 .21 4.24 4 .11
1 .78 2 .83 1-75
Participants (age)
Mean
Chasing (s) SD
N
290 314
3 .87 4 .00
1 .75 1 .70
78 58
54 34 19
3 .29 12 .51 3 .56
1-75 11 .22 3 .22
32 36 16
N
OWENS : AGGRESSION AND PLAY IN BABOONS YOUNG MALE-MALE PLAY N- 288 1464 1214 100-
81O 1400
870 r-
877
759 YOUNG ADULT MALE-MALE MALE-MALE AGGRESSION AGGRESSION 78 114
373
Mauling r
Chasing
80-
----------
~~ 60-
Wrestling
40
Sparring
----------- \, \\
w \ ~ 20
mutual biting
25 AGE I MONTHS Fig. 1 . The proportions in which six movement patterns were used in play and aggression between males . Each column for play represents one individual, whose mean age during the 3 to 4 month recording period is plotted .
5
15
\ % •
10
20
YOUNG FEMALE-FEMALE PLAY N= 176
251
29989
339
149
YOUNG ADULT FEMALE- FEMALEFEMALE FEMALE AGGRESSION AGGRESSION 29 126
Mauling
rr
----------------Chasing
U a 40
J
-t =al t29 Wrestling
rrr
20 Mutual biting 0 0
35 40 25 30 AGE IMONTHS Fig . 2 . The proportions in which six movement patterns were used in play and aggression between females . Each column for play represents one individual, whose mean age during the recording period is plotted .
5
10
15
20
760
ANIMAL BEHAVIOUR, 23, 4 KEY ofpercent bites 0 1-5 6-10 11-20 21-30 31-40 41-50 51
Fig . 3 . Regions of the body bitten during play by males (above) and by females (below) . adult male aggression, probably because the chaser more often caught up with its partner, due either to the disparity in size between the participants (this also applies to young-young aggression) or to the chasee slowing down and allowing the chaser to catch up, or turning to face its oncoming partner. The Proportions in Which the Movement Patterns were Used in Play and Aggression Male-male interactions involved a greater total proportion of mutual movement patterns (mutual biting, sparring and wrestling) than did female-female interactions in play (x2 = 351-4, df-- 1, P < 0 .001 : summing data for all individuals), young-young aggression (x2 = 7 .5, df = 1, P < 0-01) and adult-adult aggression (x2 = 73 -4, df = 1, P < 0-001) : see Figs 1 and 2 . All six movement patterns occurred in both male and female play and in adult and young male-male aggression, but some mutual patterns
were absent from female-female aggression . Thus wrestling and sparring were absent from young female aggression, and no mutual patterns at all occurred in adult female aggression . Despite these parallels in the sex differences in play and aggression in the use of the six movement patterns, there were also differences between play and aggression within each sex . In males (Fig. 1), mutual patterns in play comprised a median over all age groups of 66 per cent of total patterns, compared with 14 per cent in young male aggression and 46 per cent in adult male aggression (x2 = 22 .1 and 21 .1 respectively, df = 1, P < 0-001 in both cases : summing play data for all individuals) . These differences were due to the relatively greater incidence of chasing in young and adult aggression than in play, and a relatively greater incidence of wrestling and mutual biting in play . Sparring (a mutual category) was, however, commoner in adult male aggression than in play . In females (Fig . 2), mutual patterns in play
OWENS : AGGRESSION AND PLAY IN BABOONS
Fig. 4 . Regions of the body that received wounds in adult male-male aggression (above), and the regions of the body bitten in adult female-female aggression (below) . comprised a median of 37 per cent of total patterns, compared with 3 per cent in young female aggression and 0 per cent in adult female aggression . All mutual patterns occurred relatively more and all non-mutual patterns occurred relatively less in play than in either young or adult female aggression, with the exception that mauling occurred much more in play than in adult female aggression . Sparring tended to become a more common component of male play with age (see Owens 1975 and Fig . 1), and in this respect, male play became more like male aggression with age . Female play showed no clear tendency to become more like aggression (Fig . 2). Biting in Aggression and Play In play, both males and females directed about 75 per cent of bites to the anterior regions of the body (head, neck, shoulders and arms),
761
Fig. 5. Regions of the body bitten during young-young aggression by males (above) and by females (below) . but some biting occurred in all regions (Fig . 3) . Females bit the side of the neck and the cheeks less than did males, and the shoulders, top of the head, back of the neck and hands somewhat more . Most of the data for females refer to female-male biting (see Methods) . Males bit the neck more than any other region, and since it was difficult for two baboons to bite one another's necks simultaneously, it is probable that the different distribution of female biting was due to the rougher play of males preventing females from biting male's necks. Adult male wounds occurred in most regions of the body, but more than 50 per cent were on the face (Fig. 4). The bare face is much more likely to be wounded than are parts of the body covered by fur. The neck and shoulders of adult males are protected by a thick mane, and the number of wounds observed in this region probably underestimates the amount of biting . However, most wounds were inflicted on the
ANIMAL BEHAVIOUR, 23, 4
7 62
anterior regions of the body . This is to be expected, since nearly all fighting between adult males was in the form of sparring; in which the partners stand facing each other . In aggression between adult females, biting was confined to the back of the neck, back and tail (Fig. 4). Aggressive . interactions between adult females were more stereotyped than those between adult males, and involved a `punishing' bite by the aggressor from behind, often following a short chase . The aggressee usually adopted a submissive posture, turning her rump towards the aggressor and crouching . In aggression between young males and females, although the data are rather few, the distribution of biting was clearly very similar to that in adult female aggression, bites being confined to the back of the neck, back and tail (Fig . 5) . Relationships Between Individuals in Aggression and Play The relationships between individuals in play were described in an earlier paper (Owens
1975) . In male-male play, the direction of mauling and chasing between pairs of individuals could largely be predicted by a linear hierarchy with age . The older of two male partners tended more often to maul or chase his partner than he was mauled or chased by him . Roles in play were, however, often reversed with respect to the hierarchy (Table II) . In aggression between young males, the direction of mauling and chasing was also a function of the relative age of the participants . The older male was, however, almost always the `winner' of aggressive encounters, and roles were hardly ever reversed. Thus in young male-male interactions, role reversal was a much more common feature of play than of aggression (x2 = 34 .6 ; df = 1 ; P < 0 .001) . In young female-female interactions, role reversal was again more common in play than aggression with respect to the hierarchies that best described the data in each case (x2 = 5 .9 ; df = 1 ; P < 0 .02 : Table II) . The direction of play movements between pairs of individuals was not clearly related to age, though inter-
Table U. Comparison of the Direction of Interactions (Mauling and Chasing) Between Pairs of Individuals in Aggression and Play Proportion of pairs of individuals in which the animal higher in the hierarchy was more often the mauler or the chaser than the animal lower in the hierarchy
Type of interaction PLAY Male-male Female-female
Proportion of interactions in which roles were reversed with respect to the hierarchy
12/15
No. of individuals observed 7
6 09
AGGRESSION Young male-male Young female-female Adult male-mate Adult female-female
18/87 1/19 21/77 2/190
24/36 74/74
5 13 14
Note that play and aggression were not observed between all possible pair combinations . Table III . Comparison of the Rank Order of Young Females Determined by Age, Interactions in Play and Aggression, and the Ranks of Their Mothers Age
Play
Oldest (37 months)
Gd D M L
Highest ranking
M Pb Gd D
Youngest (11 months)
Pb
Lowest ranking
L
Aggression Gd D M Pb L
Mothers D Pb M L Gd
OWENS : AGGRESSION AND PLAY IN BABOONS actions in aggression were, with the exception of individuals Pb and L . There was no apparent relationship between the ranks of young females in clay or aggression and the ranks of their mothers (Table III) . In aggression between adult males, animals could be ordered such that, in twenty-four out of thirty-six pairs of individuals for which there are data, the animal higher in the hierarchy was the mauler, chaser or biter more often than the animal lower in the hierarchy . In eight adult male pairs, aggressive movements occurred equally often in either direction. Thus despite frequent role reversal, the overall direction of interactions could be described fairly accurately by a linear hierarchy (Table II) . (The data for adult males are rather few, however, and with more data the existence of more complex relationships might emerge.) The relative ages of adult males could be estimated by the extent of wearing on the teeth and the development of the mane . Unlike male play, the highest-ranking adult males were not necessarily the oldest . The three highest-ranking males had fully mature coats but relatively unworn teeth . Adult females could be ordered in a linear hierarchy in which higher-ranking females were almost always the `winners' of aggressive encounters with lower-ranking females . Roles were hardly ever reversed with respect to the hierarchy over a period of 18 months (Table II) . As in adult males, rank did not appear to be linearly related to age, but unlike adult males, adult females did not appear to change rank as they became older . Adult female aggressive interactions were generally diadic, and it was not usual for a third female to be enlisted in support of one of the participants . Troop
763
changes were never observed in the study troop (though one example of a troop change by an adult female is known from another Gombe troop ; Nash 1973) . Discussion Play and aggression hierarchies were divisible into two sorts (1) Those in which the direction of interactions was very predictable and the subordinate rarely retaliated . Young-young and adult female aggression hierarchies were of this type. (2) Those in which the direction of interactions followed a general pattern, but reversal of roles, with respect to the hierarchies that best described the data, was common . Play and adult male aggression hierarchies were of this type . In type 1 interactions, the parts bitten were confined to the back of the neck, back and tail, whereas in type 2 interactions, nearly all parts of the body were bitten, and bites were concentrated around the anterior regions . The percentage movement patterns were2 `mutual' wasoflower in type I than that in type interactions . These conclusions are summarized in Table IV. These parallels are expected since, in those classes of interactions in which the relationship between partners was very predictable, the subordinate partner did not usually attempt to retaliate, but tended to present in submission to or run away from the dominant partner, which then often gave a `punishing' bite to the neck, back or tail. Such bites seemed to be a ritualized re-affirmation of an existing relationship . In less-predictable relationships, the subordinate more often retaliated, and instead of always
Table IV. The Extent of Role Reversal (i.e. the Percentage of Instances in which the Lowerranking Animal was the Mauler, Biter or Chaser), the Parts Bitten, and the Percentage of Movement Patterns that were `Mutual' in Six Categories of Play and Aggression Type of interaction
Per cent role reversal
Parts bitten
Per cent mutual movement patterns
PLAY Male-male Female-female
37 31
All parts All parts
66 37
AGGRESSION Adult male-male Young male-male Young female-female Adult female-female
27 1 5 1
Nearly all parts Neck, back and tail only Neck, back and tail only Neck, back and tail only
46 14 3 0
7 64
ANIMAL BEHAVIOUR, 23, 4
presenting to or running away from its partner, often turned and faced it . Thus more biting to the anterior part of the body, and more mutual interactions would be expected . In male-male aggression, interactions between young animals (less than 5 years old) were linearly related to age, and very predictable, whereas those between adults were less predictable and not linearly related to age . Between 5 and 7 years of age, therefore, as males differing in age attained their full size, the nature of aggressive interactions changed . The frequent reversal of roles in adult-male aggression probably allowed animals to re-assess the strength and fighting ability of their partners . Males which had reached full maturity were generally high in the aggression hierarchy, and older males probably gradually lost their position . Flexibility of roles probably also allowed males to take advantage of changes in supportive relationships (see Hall & DeVore 1965 ; Owens in preparation ; Saayman 1971) for example when a new male joined from another troop (Nash 1973) . Since male baboons high in the aggression hierarchy may sire the most offspring (Hall & DeVore 1965) and have greater freedom of access to food, great advantage could accrue to males that maximized their aggressive status . There are therefore likely to be strong selection pressures amongst males for the ability to assess the fighting ability of other males rapidly and accurately, to develop effective fighting strategies, and to enlist the support of other males . It seems likely that the development of these abilities may be one of the functions of male-male play, in which, as in adult male-male aggression (but not young male-male aggression), roles were frequently reversed. Role reversal in play is widespread amongst other primates (e .g. Bertrand 1969 ; Loizos 1967b ; Jay Dolhinow & Bishop 1970) . Play also provided the opportunity for more prolonged contact than aggression, and this may have facilitated the learning process . In male-male play, the proportions in which the movement patterns were used became with age somewhat more like those in aggression . Notably, there was an increase in the frequency of sparring . It did not seem, however, that play was necessary for the development of the use of sparring patterns, since sparring was already occurring regularly in young male aggression . Sparring involved less physical contact than did wrestling, and probably indicated that the participants were somewhat afraid of each other .
An increase in the `roughness' of rough-andtumble play in baboons has been previously described (Hall & DeVore 1965) . In young female-female interactions, status in play and aggression appeared to be unrelated. The adult female aggression hierarchy, unlike that in young females, did not appear to be determined by age . Thus it is possible that in females, individual relationships are established in play, and are maintained into adulthood . Adult female agonistic relations were characterized by their relative stability and inflexibility, and in contrast to play, seemed unlikely to offer much opportunity for the establishment of new social relationships . Rowell (1966), however, points out that the adult female aggression hierarchy in captive baboons is not completely static, and that changes in rank may originate from `friendly' behaviour such as grooming, in which the direction of interactions is less consistent than in agonistic behaviour . Studies of aggression in some non-primate species, for example feral goats, also indicate that interactions involving role reversal are characteristic of behaviour in which rank is being established (Shank 1972) . The selection pressures operating upon adult females are likely to be somewhat different from those operating on adult males. Adult females do not all come into oestrus at the same time (Owens, in preparation), and there is consequently less necessity to compete for mates ; all oestrous females are consorted by males . The stable rank order amongst females may serve to minimize the duration and intensity of disputes over food, sleeping places, or social companions . Although it may be advantageous to be high-ranking, there are likely also to be strong selection pressures against severe fighting, since this is likely to affect the survival of young . For example, Nash (1974) describes a premature still-birth in a baboon, apparently induced by one of the extremely rare severe fights amongst adult females. It may therefore be more beneficial for adult females to accept their rank, once established, and to gain access to desired objects by more subtle social subterfuge . Acknowledgments I wish to thank Jane and Hugo Van Lawick for allowing me to use the facilities of the Gombe Stream Research Centre, Tanzania, as a base for my field work, and for their help and generosity during the study . I also express my gratitude to my research supervisor, Professor
OWENS : AGGRESSION AND PLAY IN BABOONS R . A . Hinde for his constant advice and encouragement . The work was supported by a Medical Research Council grant for training in research methods. REFERENCES Altmann, S . A . (1962) . Social behaviour of anthropoid primates : analysis of recent concepts . In : Roots of Behaviour (Ed . by E . L. Bliss), pp . 277-285 . New York : Hoeber. Bateson, G. (1955). A theory of play and fantasy . Psychiatric Research Reports, A . 2, 39-51 . Bekoff, M . (in press) . The Communication of Play Intention : Are Play Signals Functional? Bertrand, M . (1969) . The behavioural repertoire of the stumptail macaque. Biblio. Primatol., 11 . Basel : Karger. Hall, K . R. L. (1962) . The sexual, agonistic and derived social behaviour patterns of the wild chacma baboon Papio ursinus . Proc . Zool . Soc . Lond., 139, 283-327 . Hall, K. R . L . & DeVore, 1 . (1965) . Baboon social behaviour. In : Primate Behaviour, Field Studies of Monkeys and Apes (Ed. by I . DeVore), pp. 53-110 . New York : Holt, Rinehart and Winston. Harlow, H . F. & Harlow, M . K. (1965). The affectional systems. In : Behaviour of Nonhuman Primates, II (Ed . by A . M . Schrier, H . F. Harlow & F. Stollnitz), pp . 287-334. New York and London : Academic Press . Jay Dolhinow, P. C . & Bishop, N . (1970) . The development of motor skills and social relationships among primates through play . Minnesota Symposia on Child Psychology, IV . University of Minnesota Press. Loizos, C. (1966) . Play in mammals. Symp . Zool. Soc ., Lond., 18, 1-9 .
76 5
Loizos, C . (1967a) . An ethological study of play in captive chimpanzees. Proc . 2nd International Congress of Primatologists, Atlanta, Georgia . Basel : Ranger. Loizos, C . (1967b). Play behaviour in higher primates : a review . In : Primate Ethology (Ed . by D. Morris), pp . 176-218 . London : Wiedenfield and Nicolson . Lorenz, K . (1956). Plays and vacuum activities . Symposium L'Instinct dans le comportement des Animaux et de L'Homme, 633-645 . Nash, L. T. (1973). Social behaviour and social development in baboons (Papio anubis) at the Gombe Stream National Park, Tanzania . Doctoral dissertation, University of California, Berkeley. Nash, L. T . (1974) . Parturition in a feral baboon (Papio anubis) . Primates, 15, 279-285 . Owens, N. W . (1975) . Social play behaviour in freeliving baboons, Papio anubis . Anim . Behav ., 23, 387-408 . Owens, N. W . (in preparation) . The development of sociosexual behaviour in free-living baboons, Papio anubis. Rowell, T . E . (1966) . Hierarchy in the organisation of a captive baboon troop. Anim . Behav ., 14, 430-443. Saayman, G . S. (1971) . Behaviour of adult males in a troop of free-ranging chacma, baboons (Papio ursinus) . Folia Primatol., 15, 36-57 . Shank, C . C . (1972) . Some aspects of social behaviour in a population of feral goats (Capra Hircus) . Z. Tierpsychol., 30, 488-528 . Van Hooff, J. A . (1967) . The facial expressions of the catarrhine monkeys and apes . In : Primate Ethology (Ed. by D . Morris), pp . 7-68 . (Received 24 May 1974 ; first revision 11 January 1975 ; second revision 27 January 1975 ; MS. number: 1398)
establish individual relationships (Hall 1962 ; Harlow & Harlow 1965) . No previous studies have provided hard evidence, however, as to the types of relationship established in play, nor whether these may persist into adulthood . Methods The study was carried out in the Gombe Stream National Park, Tanzania, between January and November, 1970 and April and August, 1971 . The study area, the baboon troop, and the field methods employed have already been described (Owens 1975) . Attention was focussed on the relative frequency of occurrence of different movement patterns in play and aggression . Aggression was separated from aggressive play by the criterion that at least one of the participants showed gestures of intense threat . The following details of aggressive behaviour were recorded, using a portable tape-recorder and stop-watch, and later transcribing to a data sheet . (a) The length of contacts (comprising wrestling, sparring, mauling or biting) and the length of chases . A contact or chase was considered to have ended when the sequence was interrupted by a break of 1 s or more . (b) The movement patterns that occurred in each interaction . The following six patterns were recognized : (i) Wrestling : the participants roll and grapple together on the ground : usually accompanied by mutual biting . (ii) Sparring : the partners stand facing each other, grapple with the arms and hit one another about the head ; rolling on the ground not involved .
attributed to certain characteristics of the organization of play movement patterns (e .g. Lorenz 1956 ; Loizos 1966) . Few studies have compared quantitatively the nature of interactions in play and non-play to show exactly what these differences are (but see Bekoff in press ; Loizos 1967a) . Such studies are essential to an understanding of the causation and function of play. It has been suggested that through play, primates may develop motor skills (Loizos 1966 ; Jay Dolhinow & Bishop 1970) and *Present address : 39 Caernarvon Road, Norwich, Norfolk . 757
758
ANIMAL BEHAVIOUR, 23, 4
{iii) Mutual, biting : both partners bite the other. (iv) Mauling : interactions involving contact in which one partner is inactive throughout the sequence and is mauled by its partner . (v) Non-mutual biting : only one partner bites. (vi) Approach-withdrawal : comprises chasing or being chased. The first three movement pattern categories are `mutual' categories, i .e. each baboon is equally involved in the interaction . The second three categories are `non-mutual', i .e. one baboon has an active and the other a passive role. In addition, the parts bitten in young-young and adult female aggression were recorded concurrently . The body was arbitrarily divided into twenty anatomical regions, and a symbol used to denote each region for recording purposes. Separate observations were made of the parts bitten in play and adult male aggression. To record play biting, one playing animal was watched for one bout at a time . (Note that a play bout was defined as a sequence of play uninterrupted by a break of 1 s or more) . The identity of its play partners and all the parts that received bites from the target animal were noted, regardless of the length of time that each part was bitten . The procedure was then repeated for the next bout, though sometimes one or two intervening bouts would be missed . Six males and four females were observed, ranging in age between 12 and 45 months . The data for male biting comprised about 95 per cent male-male biting and 5 per cent malefemale biting . Data for females comprised about 95 per cent female-male biting and 5 per cent female-female biting . It was not possible to record the parts bitten in aggression between adult males directly, because biting was usually too fast and too brief to see . Instead, wounds received by adult males
(both flesh wounds and pieces of fur removed) were used as an indication of the regions bitten . It is most unlikely that such wounds would be inflicted other than by an adult male baboon . Other troop members did not bite adult males except in play, and only adult males had sufficiently long canines to give such wounds . It is possible that some of the wounds may have been inflicted during fights with predators, such as chimpanzees, but such fights were never observed to result in wounding, and were relatively very infrequent. Only one of the thirty-five wounds recorded was observed at the time it was inflicted, and the others were seen up to 2 weeks afterwards. Results The Length of Instances of Contact and Chasing in Play and Aggression The mean length of contacts was greater in male-male play than in female-female play and greater overall in play than aggression (P < 0 .001 in both cases ; d test ; Table I) . The length of contacts in play also showed more variance than in aggression, owing to the occurrence of some very long contacts (up to 60 s) in play. The mean length of chases was greater in adult male aggression than in any other category of aggression or play (P < 0 .001 ; d test) . The tendency towards shorter contacts in aggression than in play was probably a result of the participants' greater fear of one another in aggression . Similarly, the long chases characteristic of adult males were probably a reflection of their fear of engaging in physical contact with one another . Even during the brief fights that did occur, wounds were often inflicted with the canine teeth. In adult female aggression however, chases were relatively short because the aggressee tended to stop and present in submission to the aggressor, rather than attempt to escape. Play chases were shorter than those in
Table L The Length of Instances of Contact and Chasing in Play and Aggression Mean
Contact (s) SD
PLAY Male-male (5-37 months) Female-female (11-37 months)
7 .56 5 .57
8 .79 5 .64
AGGRESSION Young-young (5-60 months) Adult male-male (> 7 years) Adult female-female (> 5 years)
3 .21 4.24 4 .11
1 .78 2 .83 1-75
Participants (age)
Mean
Chasing (s) SD
N
290 314
3 .87 4 .00
1 .75 1 .70
78 58
54 34 19
3 .29 12 .51 3 .56
1-75 11 .22 3 .22
32 36 16
N
OWENS : AGGRESSION AND PLAY IN BABOONS YOUNG MALE-MALE PLAY N- 288 1464 1214 100-
81O 1400
870 r-
877
759 YOUNG ADULT MALE-MALE MALE-MALE AGGRESSION AGGRESSION 78 114
373
Mauling r
Chasing
80-
----------
~~ 60-
Wrestling
40
Sparring
----------- \, \\
w \ ~ 20
mutual biting
25 AGE I MONTHS Fig. 1 . The proportions in which six movement patterns were used in play and aggression between males . Each column for play represents one individual, whose mean age during the 3 to 4 month recording period is plotted .
5
15
\ % •
10
20
YOUNG FEMALE-FEMALE PLAY N= 176
251
29989
339
149
YOUNG ADULT FEMALE- FEMALEFEMALE FEMALE AGGRESSION AGGRESSION 29 126
Mauling
rr
----------------Chasing
U a 40
J
-t =al t29 Wrestling
rrr
20 Mutual biting 0 0
35 40 25 30 AGE IMONTHS Fig . 2 . The proportions in which six movement patterns were used in play and aggression between females . Each column for play represents one individual, whose mean age during the recording period is plotted .
5
10
15
20
760
ANIMAL BEHAVIOUR, 23, 4 KEY ofpercent bites 0 1-5 6-10 11-20 21-30 31-40 41-50 51
Fig . 3 . Regions of the body bitten during play by males (above) and by females (below) . adult male aggression, probably because the chaser more often caught up with its partner, due either to the disparity in size between the participants (this also applies to young-young aggression) or to the chasee slowing down and allowing the chaser to catch up, or turning to face its oncoming partner. The Proportions in Which the Movement Patterns were Used in Play and Aggression Male-male interactions involved a greater total proportion of mutual movement patterns (mutual biting, sparring and wrestling) than did female-female interactions in play (x2 = 351-4, df-- 1, P < 0 .001 : summing data for all individuals), young-young aggression (x2 = 7 .5, df = 1, P < 0-01) and adult-adult aggression (x2 = 73 -4, df = 1, P < 0-001) : see Figs 1 and 2 . All six movement patterns occurred in both male and female play and in adult and young male-male aggression, but some mutual patterns
were absent from female-female aggression . Thus wrestling and sparring were absent from young female aggression, and no mutual patterns at all occurred in adult female aggression . Despite these parallels in the sex differences in play and aggression in the use of the six movement patterns, there were also differences between play and aggression within each sex . In males (Fig. 1), mutual patterns in play comprised a median over all age groups of 66 per cent of total patterns, compared with 14 per cent in young male aggression and 46 per cent in adult male aggression (x2 = 22 .1 and 21 .1 respectively, df = 1, P < 0-001 in both cases : summing play data for all individuals) . These differences were due to the relatively greater incidence of chasing in young and adult aggression than in play, and a relatively greater incidence of wrestling and mutual biting in play . Sparring (a mutual category) was, however, commoner in adult male aggression than in play . In females (Fig . 2), mutual patterns in play
OWENS : AGGRESSION AND PLAY IN BABOONS
Fig. 4 . Regions of the body that received wounds in adult male-male aggression (above), and the regions of the body bitten in adult female-female aggression (below) . comprised a median of 37 per cent of total patterns, compared with 3 per cent in young female aggression and 0 per cent in adult female aggression . All mutual patterns occurred relatively more and all non-mutual patterns occurred relatively less in play than in either young or adult female aggression, with the exception that mauling occurred much more in play than in adult female aggression . Sparring tended to become a more common component of male play with age (see Owens 1975 and Fig . 1), and in this respect, male play became more like male aggression with age . Female play showed no clear tendency to become more like aggression (Fig . 2). Biting in Aggression and Play In play, both males and females directed about 75 per cent of bites to the anterior regions of the body (head, neck, shoulders and arms),
761
Fig. 5. Regions of the body bitten during young-young aggression by males (above) and by females (below) . but some biting occurred in all regions (Fig . 3) . Females bit the side of the neck and the cheeks less than did males, and the shoulders, top of the head, back of the neck and hands somewhat more . Most of the data for females refer to female-male biting (see Methods) . Males bit the neck more than any other region, and since it was difficult for two baboons to bite one another's necks simultaneously, it is probable that the different distribution of female biting was due to the rougher play of males preventing females from biting male's necks. Adult male wounds occurred in most regions of the body, but more than 50 per cent were on the face (Fig. 4). The bare face is much more likely to be wounded than are parts of the body covered by fur. The neck and shoulders of adult males are protected by a thick mane, and the number of wounds observed in this region probably underestimates the amount of biting . However, most wounds were inflicted on the
ANIMAL BEHAVIOUR, 23, 4
7 62
anterior regions of the body . This is to be expected, since nearly all fighting between adult males was in the form of sparring; in which the partners stand facing each other . In aggression between adult females, biting was confined to the back of the neck, back and tail (Fig. 4). Aggressive . interactions between adult females were more stereotyped than those between adult males, and involved a `punishing' bite by the aggressor from behind, often following a short chase . The aggressee usually adopted a submissive posture, turning her rump towards the aggressor and crouching . In aggression between young males and females, although the data are rather few, the distribution of biting was clearly very similar to that in adult female aggression, bites being confined to the back of the neck, back and tail (Fig . 5) . Relationships Between Individuals in Aggression and Play The relationships between individuals in play were described in an earlier paper (Owens
1975) . In male-male play, the direction of mauling and chasing between pairs of individuals could largely be predicted by a linear hierarchy with age . The older of two male partners tended more often to maul or chase his partner than he was mauled or chased by him . Roles in play were, however, often reversed with respect to the hierarchy (Table II) . In aggression between young males, the direction of mauling and chasing was also a function of the relative age of the participants . The older male was, however, almost always the `winner' of aggressive encounters, and roles were hardly ever reversed. Thus in young male-male interactions, role reversal was a much more common feature of play than of aggression (x2 = 34 .6 ; df = 1 ; P < 0 .001) . In young female-female interactions, role reversal was again more common in play than aggression with respect to the hierarchies that best described the data in each case (x2 = 5 .9 ; df = 1 ; P < 0 .02 : Table II) . The direction of play movements between pairs of individuals was not clearly related to age, though inter-
Table U. Comparison of the Direction of Interactions (Mauling and Chasing) Between Pairs of Individuals in Aggression and Play Proportion of pairs of individuals in which the animal higher in the hierarchy was more often the mauler or the chaser than the animal lower in the hierarchy
Type of interaction PLAY Male-male Female-female
Proportion of interactions in which roles were reversed with respect to the hierarchy
12/15
No. of individuals observed 7
6 09
AGGRESSION Young male-male Young female-female Adult male-mate Adult female-female
18/87 1/19 21/77 2/190
24/36 74/74
5 13 14
Note that play and aggression were not observed between all possible pair combinations . Table III . Comparison of the Rank Order of Young Females Determined by Age, Interactions in Play and Aggression, and the Ranks of Their Mothers Age
Play
Oldest (37 months)
Gd D M L
Highest ranking
M Pb Gd D
Youngest (11 months)
Pb
Lowest ranking
L
Aggression Gd D M Pb L
Mothers D Pb M L Gd
OWENS : AGGRESSION AND PLAY IN BABOONS actions in aggression were, with the exception of individuals Pb and L . There was no apparent relationship between the ranks of young females in clay or aggression and the ranks of their mothers (Table III) . In aggression between adult males, animals could be ordered such that, in twenty-four out of thirty-six pairs of individuals for which there are data, the animal higher in the hierarchy was the mauler, chaser or biter more often than the animal lower in the hierarchy . In eight adult male pairs, aggressive movements occurred equally often in either direction. Thus despite frequent role reversal, the overall direction of interactions could be described fairly accurately by a linear hierarchy (Table II) . (The data for adult males are rather few, however, and with more data the existence of more complex relationships might emerge.) The relative ages of adult males could be estimated by the extent of wearing on the teeth and the development of the mane . Unlike male play, the highest-ranking adult males were not necessarily the oldest . The three highest-ranking males had fully mature coats but relatively unworn teeth . Adult females could be ordered in a linear hierarchy in which higher-ranking females were almost always the `winners' of aggressive encounters with lower-ranking females . Roles were hardly ever reversed with respect to the hierarchy over a period of 18 months (Table II) . As in adult males, rank did not appear to be linearly related to age, but unlike adult males, adult females did not appear to change rank as they became older . Adult female aggressive interactions were generally diadic, and it was not usual for a third female to be enlisted in support of one of the participants . Troop
763
changes were never observed in the study troop (though one example of a troop change by an adult female is known from another Gombe troop ; Nash 1973) . Discussion Play and aggression hierarchies were divisible into two sorts (1) Those in which the direction of interactions was very predictable and the subordinate rarely retaliated . Young-young and adult female aggression hierarchies were of this type. (2) Those in which the direction of interactions followed a general pattern, but reversal of roles, with respect to the hierarchies that best described the data, was common . Play and adult male aggression hierarchies were of this type . In type 1 interactions, the parts bitten were confined to the back of the neck, back and tail, whereas in type 2 interactions, nearly all parts of the body were bitten, and bites were concentrated around the anterior regions . The percentage movement patterns were2 `mutual' wasoflower in type I than that in type interactions . These conclusions are summarized in Table IV. These parallels are expected since, in those classes of interactions in which the relationship between partners was very predictable, the subordinate partner did not usually attempt to retaliate, but tended to present in submission to or run away from the dominant partner, which then often gave a `punishing' bite to the neck, back or tail. Such bites seemed to be a ritualized re-affirmation of an existing relationship . In less-predictable relationships, the subordinate more often retaliated, and instead of always
Table IV. The Extent of Role Reversal (i.e. the Percentage of Instances in which the Lowerranking Animal was the Mauler, Biter or Chaser), the Parts Bitten, and the Percentage of Movement Patterns that were `Mutual' in Six Categories of Play and Aggression Type of interaction
Per cent role reversal
Parts bitten
Per cent mutual movement patterns
PLAY Male-male Female-female
37 31
All parts All parts
66 37
AGGRESSION Adult male-male Young male-male Young female-female Adult female-female
27 1 5 1
Nearly all parts Neck, back and tail only Neck, back and tail only Neck, back and tail only
46 14 3 0
7 64
ANIMAL BEHAVIOUR, 23, 4
presenting to or running away from its partner, often turned and faced it . Thus more biting to the anterior part of the body, and more mutual interactions would be expected . In male-male aggression, interactions between young animals (less than 5 years old) were linearly related to age, and very predictable, whereas those between adults were less predictable and not linearly related to age . Between 5 and 7 years of age, therefore, as males differing in age attained their full size, the nature of aggressive interactions changed . The frequent reversal of roles in adult-male aggression probably allowed animals to re-assess the strength and fighting ability of their partners . Males which had reached full maturity were generally high in the aggression hierarchy, and older males probably gradually lost their position . Flexibility of roles probably also allowed males to take advantage of changes in supportive relationships (see Hall & DeVore 1965 ; Owens in preparation ; Saayman 1971) for example when a new male joined from another troop (Nash 1973) . Since male baboons high in the aggression hierarchy may sire the most offspring (Hall & DeVore 1965) and have greater freedom of access to food, great advantage could accrue to males that maximized their aggressive status . There are therefore likely to be strong selection pressures amongst males for the ability to assess the fighting ability of other males rapidly and accurately, to develop effective fighting strategies, and to enlist the support of other males . It seems likely that the development of these abilities may be one of the functions of male-male play, in which, as in adult male-male aggression (but not young male-male aggression), roles were frequently reversed. Role reversal in play is widespread amongst other primates (e .g. Bertrand 1969 ; Loizos 1967b ; Jay Dolhinow & Bishop 1970) . Play also provided the opportunity for more prolonged contact than aggression, and this may have facilitated the learning process . In male-male play, the proportions in which the movement patterns were used became with age somewhat more like those in aggression . Notably, there was an increase in the frequency of sparring . It did not seem, however, that play was necessary for the development of the use of sparring patterns, since sparring was already occurring regularly in young male aggression . Sparring involved less physical contact than did wrestling, and probably indicated that the participants were somewhat afraid of each other .
An increase in the `roughness' of rough-andtumble play in baboons has been previously described (Hall & DeVore 1965) . In young female-female interactions, status in play and aggression appeared to be unrelated. The adult female aggression hierarchy, unlike that in young females, did not appear to be determined by age . Thus it is possible that in females, individual relationships are established in play, and are maintained into adulthood . Adult female agonistic relations were characterized by their relative stability and inflexibility, and in contrast to play, seemed unlikely to offer much opportunity for the establishment of new social relationships . Rowell (1966), however, points out that the adult female aggression hierarchy in captive baboons is not completely static, and that changes in rank may originate from `friendly' behaviour such as grooming, in which the direction of interactions is less consistent than in agonistic behaviour . Studies of aggression in some non-primate species, for example feral goats, also indicate that interactions involving role reversal are characteristic of behaviour in which rank is being established (Shank 1972) . The selection pressures operating upon adult females are likely to be somewhat different from those operating on adult males. Adult females do not all come into oestrus at the same time (Owens, in preparation), and there is consequently less necessity to compete for mates ; all oestrous females are consorted by males . The stable rank order amongst females may serve to minimize the duration and intensity of disputes over food, sleeping places, or social companions . Although it may be advantageous to be high-ranking, there are likely also to be strong selection pressures against severe fighting, since this is likely to affect the survival of young . For example, Nash (1974) describes a premature still-birth in a baboon, apparently induced by one of the extremely rare severe fights amongst adult females. It may therefore be more beneficial for adult females to accept their rank, once established, and to gain access to desired objects by more subtle social subterfuge . Acknowledgments I wish to thank Jane and Hugo Van Lawick for allowing me to use the facilities of the Gombe Stream Research Centre, Tanzania, as a base for my field work, and for their help and generosity during the study . I also express my gratitude to my research supervisor, Professor
OWENS : AGGRESSION AND PLAY IN BABOONS R . A . Hinde for his constant advice and encouragement . The work was supported by a Medical Research Council grant for training in research methods. REFERENCES Altmann, S . A . (1962) . Social behaviour of anthropoid primates : analysis of recent concepts . In : Roots of Behaviour (Ed . by E . L. Bliss), pp . 277-285 . New York : Hoeber. Bateson, G. (1955). A theory of play and fantasy . Psychiatric Research Reports, A . 2, 39-51 . Bekoff, M . (in press) . The Communication of Play Intention : Are Play Signals Functional? Bertrand, M . (1969) . The behavioural repertoire of the stumptail macaque. Biblio. Primatol., 11 . Basel : Karger. Hall, K . R. L. (1962) . The sexual, agonistic and derived social behaviour patterns of the wild chacma baboon Papio ursinus . Proc . Zool . Soc . Lond., 139, 283-327 . Hall, K. R . L . & DeVore, 1 . (1965) . Baboon social behaviour. In : Primate Behaviour, Field Studies of Monkeys and Apes (Ed. by I . DeVore), pp. 53-110 . New York : Holt, Rinehart and Winston. Harlow, H . F. & Harlow, M . K. (1965). The affectional systems. In : Behaviour of Nonhuman Primates, II (Ed . by A . M . Schrier, H . F. Harlow & F. Stollnitz), pp . 287-334. New York and London : Academic Press . Jay Dolhinow, P. C . & Bishop, N . (1970) . The development of motor skills and social relationships among primates through play . Minnesota Symposia on Child Psychology, IV . University of Minnesota Press. Loizos, C. (1966) . Play in mammals. Symp . Zool. Soc ., Lond., 18, 1-9 .
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Loizos, C . (1967a) . An ethological study of play in captive chimpanzees. Proc . 2nd International Congress of Primatologists, Atlanta, Georgia . Basel : Ranger. Loizos, C . (1967b). Play behaviour in higher primates : a review . In : Primate Ethology (Ed . by D. Morris), pp . 176-218 . London : Wiedenfield and Nicolson . Lorenz, K . (1956). Plays and vacuum activities . Symposium L'Instinct dans le comportement des Animaux et de L'Homme, 633-645 . Nash, L. T. (1973). Social behaviour and social development in baboons (Papio anubis) at the Gombe Stream National Park, Tanzania . Doctoral dissertation, University of California, Berkeley. Nash, L. T . (1974) . Parturition in a feral baboon (Papio anubis) . Primates, 15, 279-285 . Owens, N. W . (1975) . Social play behaviour in freeliving baboons, Papio anubis . Anim . Behav ., 23, 387-408 . Owens, N. W . (in preparation) . The development of sociosexual behaviour in free-living baboons, Papio anubis. Rowell, T . E . (1966) . Hierarchy in the organisation of a captive baboon troop. Anim . Behav ., 14, 430-443. Saayman, G . S. (1971) . Behaviour of adult males in a troop of free-ranging chacma, baboons (Papio ursinus) . Folia Primatol., 15, 36-57 . Shank, C . C . (1972) . Some aspects of social behaviour in a population of feral goats (Capra Hircus) . Z. Tierpsychol., 30, 488-528 . Van Hooff, J. A . (1967) . The facial expressions of the catarrhine monkeys and apes . In : Primate Ethology (Ed. by D . Morris), pp . 7-68 . (Received 24 May 1974 ; first revision 11 January 1975 ; second revision 27 January 1975 ; MS. number: 1398)
