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“Aunt”-infant interaction in captive rhesus monkeys
"AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS BY T . E . ROWELL,* R. A . HINDE & Y . SPENCER-BOOTH
Sub-Department of Animal Behaviour, Cambridge University, Madingley . are presented separately from those for the other 5 . These 2 infants lived in pen I with an adolescent female who interacted with them much more than any other aunt in the population, and repeatedly "stole" them . As a result their mothers became restrictive and some measures of their behaviour fell well outside the range for the others . For instance, these 2 babies practically never went more than 2 feet from their mothers until they were 4 to 5 months old, while the others would be spending 10 to 55 per cent. of their waking hours more than 2 feet away when this age .
Introduction Recent studies have shown that in some species of mammals "maternal" behaviour towards young is shown not only by lactating females but by nearly all older animals (e .g . Dieterlin, 1959, 1962 ; Beniest-Noirot, 1958 ; Rowell, 1962) . In man this is taken for granted ; the only other primate in which it has been described (Jay, 1962) is the langur . While studying the development of behaviour in young rhesus monkeys living in small social groups, we found that the behaviour of animals other than the mother has a profound effect on the interaction between mother and infant (Hinde, Rowell & Spencer-Booth, 1964) . Since the rest of the group forms so important a part of the environment of the developing infant, we must know what sorts of behaviour its different members show to the infant, and whether they affect its development . The influence of interaction with peers on the development of social behaviour has been shown by Harlow (1962). Here we are especially concerned with the behaviour of females other than the infant's mother and more than two years of age, which we refer to as "aunts" . Some data on interaction with males and other young are also included, but play and aggression between young are not discussed .
Aunt Behaviour a. Birth and Puerperium Early in labour the mothers usually kept away from the other animals in the group, and were ignored by them . In the 2 live births observed, however, the mother was attended closely by another female in the final stages . The other 6 babies were not seen until they were a few hours old, but in 3 of these cases an aunt was then associating closely with the mother. The attendant aunt was always childless . Four of the infants were born into groups already including infants : 2 of these mothers were attended by childless aunts, and the other 2 were unattended during the hours following birth . In some cases the placenta and birth fluids were investigated by other animals who fingered, smelled and tasted them (only nulliparous females have been observed to do this) . Those mothers who did not eat the placenta, merely dragging it behind until it dropped off, nevertheless protected it from investigating monkeys, threatening them or pulling the placenta away by the cord . At one birth 2 childless females arched their backs and fingered their own vulvae as soon as they saw the baby . In 2 cases the final stages of birth excited sexual behaviour from males : in addition one female was repeatedly mounted while her baby was still wet, and a year-old male mounted a female frequently during her puerperium . During the first day or two of its life, all animals present attempted to inspect each new baby, peering into its face and reaching to touch
Material and Methods This paper is based on observation of 8 infants throughout their first year of life . They were born into 3 groups of monkeys, each consisting of a male, 3 or 4 females, and their young. The adults had been introduced as strangers : for details see Table I . Each group was kept in an outside run, 18 feet x 10 feet x 8 feet, communicating with an inside room approximately 6 feet x 6 feet x 8 feet (see Hinde & Rowell, 1962) . The behaviour of the infants themselves is described in Hinde, Rowell & Spencer-Booth (1964) . Quantitative material was not available for the first baby, so that the figures are based on the other 7 animals . In some of the following sections quantitative data for 2 of the infants *Present address : Makerere University College, Kampala Uganda . 219
220
ANIMAL BEHAVIOUR, XII,
2 -3
Table I . Composition of Groups in which Infant-Adult Interactions Described took place . Each pen had one adult male . Female Pen I
Date introduced 8 .1 .60
8 .1 .60
Age/status at introduction 1 . Multipare
Young Y b .29.8 .60
2 . ? Nullipare d b .11 .8 .62
19 .8.60
II
3 . Nullipare c . 3 yrs .
6 .2 .61
4 . ? 10+ yrs .
14 .9 .60
1 . ? Nullipare
2 . Multipare
1 .3 .61
3 . c . 3 yrs.
Died 8.4 .61 . Dominant Y and d's favourite. Aunt to later babies . Stillbirth 25 .10.60, Adopted baby after death of mother
d b .25 .7 .62
d b .16 .4 .61 S b . 6 .6.62 25.8 .60
Remarks
Dominant Y to autumn 1962.
Dominant / from autY b .10 .4 .61 umn 1962 (d b .16 .4 .63 . Baby not included in this paper) Y b .15 .4 .62
III
1 .3 .61
4 . c . 3 yrs .
3 .11 .59
1 . Adult ? Nullipare
3.11 .59
2. Adult Nullipare
7.11 .60
3.
c. 4 yrs . Nullipare
30 .11 .60
4.
c . 3 yrs . Nullipare
29.9 .62
5 . c. 3J yrs . Nullipare
it . The mothers responded as would any rhesus with a highly desirable object-clutching the baby to them, turning their backs and threatening or hitting out at those inferior in rank . Favoured individuals were sometimes allowed to display close interest in the baby, but the mothers allowed others to huddle to them or groom them only if no obvious attention was paid to the baby .
Removed from pen 19 .2.63 . Gave birth 7 .3 .63 .
Died 12 .6 .62 (abortion) Stillbirth 24 .6 .61 . Y b .22.5 .62 Abortions 10 .4 .62 (c . 3 mths .) 14 .5.62 (c . 3 mths .) (y b .23 .3 .63 . Baby not included in this paper)
b . Interaction with Babies (i) Contact During the first few weeks after birth, aunts continued to approach the infants, examining them closely or reaching out to touch them . Their behaviour was tentative, and the mother was liable to respond aggressively to their approaches . While a baby was on its mother, the aunts often seemed to use subterfuge in order
ROWELL et al. : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS to approach it-sidling up to the mother while ostensibly foraging, or grooming her until her attention was distracted, and then surreptitiously grooming the baby until she looked again . When a baby first left its mother, other monkeys watched, motionless-at their slightest move the mother was likely to pick it up again . The babies' first attempts to crawl were directed towards nearby monkeys, and as the expeditions became more frequent and prolonged, the mothers became less protective and the aunts would edge towards the babies or reach out to touch them . These tentative approaches and touches were difficult to interpret . Usually they seemed to be attempts to groom or pick up the baby, but sometimes they appeared more aggressive . When an aunt went to a baby which was off its mother, she often crouched over it, putting her arms round it as though to pick it up, and perhaps putting her muzzle to its head . The aunt walked or climbed near the baby, hovering over it, and sometimes she actually picked it up and held it to her belly, though often it faced outwards . She then occasionally appeared to be trying to mount the infant, and made pelvic thrusts . The infants, except for the 2 restricted babies mentioned, did not cling to an aunt as for normal mother-infant carrying until they were old enough to escape and return to their mothers ; on the rare occasions when an aunt did attempt to carry them away they usually fell off and were retrieved by their mothers . Later they were sometimes carried in play (see below) . Adult animals showed the same play patterns with babies as Harlow (loc . cit .) has described for infant-infant interactions . However, rough-and-tumble was not as common as preliminary enticement gestures-crouching chest to ground with mouth open, or tugging gently at the babies' arms . Older aunts especially included cuddling and mounting in play with babies, and seemed more gentle in their movements than is usual in infant-infant play . ii . Communication The noises and gestures referred to in this section are described in Hinde & Rowell (1962), Rowell & Hinde (1962) and Rowell (1962). Aunts sitting watching babies made short series of coughing grunts, at the same time bobbing their heads and wagging their tails . They did this especially when a baby first set out from its mother to explore, or when it re-
221
turned to her after exploring . Females in other cages would sometimes line the wire to watch a baby, cough-grunting as they did so . Mothers made no apparent response to cough-grunting aunts, but babies would occasionally approach them . The cough-grunt was restricted to the situation described, except for a single occasion when an aunt cough-grunted to a female in labour . Aunts often lip-smacked to a baby when it was facing towards them, and they sometimes presented their hindquarters . The latter response was given both to mother and baby during the first few days of life, and later to infants away from their mothers . The younger babies did not respond, but older ones often stood up to sniff at the aunt's rump, and by 6 months they would sometimes attempt to groom or mount in adult fashion . Aunts also presented to the mother when they had frightened a baby, or when the mother was beginning to stop the aunt interacting with her baby . Infants also occasionally presented to aunts, the earliest record being in week 16 . This became more common after the end of the first year . Aunts responded to many of the noises and gestures made by the babies . Cries of fear were nearly always reacted to instantly by the mother going to the baby, but aunts often started towards it as well, and cough-grunted loudly when the mother rescued it . As the babies began to develop adult communication patterns, such as greeting growls or soliciting-for-grooming postures, the aunts responded appropriately, often making loud "pleasure noises" themselves . iii . Protection Aunts attendant on a newly parturient mother threatened other animals in the group, Males, too, were more than usually protective to new mothers, and in some cases defended them from females which they normally supported . As the infants grew, aunts sometimes watched them when they tried new physical feats and hovered anxiously nearby, going to the rescue if necessary . They seemed to be aware of dangers to young infants-for instance showing care when using the heavy swing door connecting the two parts of the pen if babies were near, and occasionally holding it open for an infant to scramble through . When a baby approached the observer an aunt would sometimes threaten, with the result that the baby went away, and on a few occasions an aunt punished another female
222
ANIMAL BEHAVIOUR, XII, 2- 3
who had been aggressive to a baby . Occasionally a baby rejected by its mother would go to an aunt and be cuddled . Some mothers used aunts as "baby-minders", leaving their baby near an aunt while they foraged . Most of the time, however, the infants were in close touch with their mother and protection by aunts was more a constant possibility than a frequent occurrence . iv . Aggression
descriptively and functionally distinct follow each other rapidly, so that the animal's behaviour appears to be highly ambivalent . In addition the pattern of interaction between an adultinfant pair changes from week to week as the baby develops ; and each mother-infant-aunt relationship has its own characteristics, depending on the history and composition of the group . In the next section some of these variations are
I.
Older babies were often a nuisance to aunts in their play, jumping over them or colliding with them . On the whole, the aunts were tolerant of such behaviour-perhaps because they were afraid of retaliation from the mother . Sometimes, however, and especially when the mother was some distance away, the baby was cuffed, bitten gently or threatened, always with one eye on the mother . Mothers were often aggressive to infants playing with their own, and drove them away if play became rough . They always drove off a baby that tried to play with their own when it was suckling or sleeping . The aggressive actions of some aunts seemed to be un- Fig. 1 . Change in incidence of various types of aunt-infant interaction with age related to the infant's behav- of infant . iour, and should perhaps be in- Ordinates indicate mean number of records per 100 minutes observation . Abscissa 6 hours a week for terpreted as an expression of the indicates age of infant : each infant was watched for at; least first six weeks, and 6 hours a fortnight thereafter the data were lumped by aunt's dominance . For instance, the fortnights for the first 6 weeks and then by months . one aunt, herself a mother, In (a) to (e) the thick line refers to the five "normal" young and the discontinwould sometimes pull and tweek uous line to the two restricted young . In (f) the aggressive responses made to the five young by aunts with infants of less than one year of their own (dotted at the 2 other babies born into first have been separated from those made by aunts without such infants (thick her group while they were on lines) line) . their own mothers . Males punished irritating babies by holding analysed. them down to the ground with one hand, and Variations in Aunt/Infant Interaction sometimes mouthing them gently, for a few (a) Age of Baby seconds . The frequencies of the various behaviour patterns shown by the aunts to the babies v . General changed as the babies grew . The changes for 5 In the preceding sections we have described of the babies are illustrated by the thick lines a number of patterns of behaviour shown by in Fig . 1, and the 2 restricted babies by the disolder rhesus monkeys towards infants. One of continuous lines (see legend to figure for conthe most striking characteristics of "aunt" beventions used in (f) . The numbers of animals haviour, however, is that patterns which are (a)
TENTATIVE APPROACHES
01
I/7
4157
WEEKS
WEEKS
ROWELL et al . : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS
from which these data were derived are small, but certain differences between the variations of the several patterns with age of infant are suggested . In the first 5 infants tentative approaches (Fig . la) were common in the first 2 to 3 weeks, but stopped by about 5 months . Brief touches (Fig . lb) were rare in the first week, became commonest in weeks 3 to 10, and ceased by the end of the year . Grooming (Fig . lc) became common after the fifth week, and was especially so in weeks 15 to 30 . Grooming of aunts by infants started later, and in the first year was common in weeks 30 to 40. Carrying and cuddling by aunts (Fig . ld) increased up to 10 to 13 weeks and then fell to a low level . It was usually associated with touching, grooming, etc . Towards the end of the year carrying again increased, but was then associated mainly with play . Play invitations (Fig. le) rose to a peak: in the third month, and then decreased . Aggression by childless aunts (Fig . If, thick line) began at about 12 weeks, and became more frequent during the fourth month . For individual babies, aggression began at different ages, between 12 and 18 weeks . The babies' mothers became aggressive or began to reject the baby at about the same time as its aunts became aggressive, or slightly earlier . Aunts with their own young (Fig . If, dotted line) were more frequently aggressive to young babies, especially in the second month . The drop in their aggressiveness at about 12 weeks may be related to decreasing protectiveness towards their own babies, rather than to the age of the attacked infant ; because births mainly occurred within a restricted breeding season, young babies tended to have aunts with young babies, and we were not able to separate these effects . The frequencies of tentative approaches and brief touches for the 2 restricted babies were similar to those for the other 5 . The frequencies of grooming and carry/cuddling were on average greater throughout, due to the activity of the female whose attentions made the mother restrictive .* The peaks of grooming, carry/ The frequency of grooming for one of the two-restricted babies was greater than that for all the others in 11 out of 13 periods in which any infant was groomed (see Fig . 1), and greater than that for 4 of them in the other 2 periods . The frequency for the other restricted baby was greater than at least 4 of the others in 9 out of these periods . The frequency of carry/cuddling for one of the restricted babies was greater than that for any other baby in 9 of the 10 periods after weeks 11 to 14 . The frequency of the other was equal to or greater than at least 4 of the non-restricted babies in 8 out of these 9 periods .
223
cuddling, play and aggression were all later than for the non-restricted infants . It will be seen that the various types of auntinfant interaction have different time courses in relation to the infant's age . The changes in response frequencies can be related partly to changes in the behaviour of the babies as they develop locomotor skills (see Hinde, Rowell & Spencer-Booth, 1964) . Thus tentative approaches were commonest when the babies were spending most of their time on their mothers, and the frequency of brief touches parallels the proportion of time the baby spent within 2 feet of its mother . Carrying/cuddling, play and grooming all increased with the amount of time the baby spent away from its mother, and therefore was available for interaction . Grooming increased especially at the time the babies began to make grooming-invitation postures (10 to 14 weeks) . These complementary changes in aunt behaviour and babies' behaviour also occurred for the two restricted babies although much later in the lives of the babies because of the restrictiveness of the mothers . The 5 "normal" babies had acquired most of their skills by the end of the third month, and the time they spent away from their mothers, after a rapid increase in the second and third months, increased only slowly up to 6 months . The frequency of some of the aunts' responses, however, changed markedly during the fourth and fifth month ; in particular the activities by which the aunts made contact with the babies decreased, and grooming, which is the behaviour typical of adult "friendly" interaction, increased . During this period the appearance of the baby changes . The new-born rhesus has a very soft coat, rather like thin-pile velvet . On its head there are two tufts of hair, separated by a centre parting . This coat is replaced at five months by a thicker one . The centre parting is lost, and the head comes to look round . (This juvenile fur is replaced by the adult grey and brown coat at just over a year .) The change in appearance and texture is gradual, but begins to be apparent at about 12 weeks . It is possible that the characteristics of the young babies may play an important part in eliciting attempts to make contact by adults . b . Difference Between Aunts i . Age and Reproductive Status
The behaviour patterns described in the preceding sections were not shown equally often by all aunts . We may now consider some data
224
ANIMAL BEHAVIOUR, XII,
2 -3
Table IL Frequency of Interaction Between Aunts and Infants when Infants were in the Age-ranges Shown, expressed as the
Median Number of Records per 1000 Minutes Observation . i Tentative Carry/ Aunt approach Touch cuddle Play grooming
Grooms aunt Aggression
Weeks over which assessed
1-14
3-52
3-52
9-44
9-44
9-44
3-52
Childless females (over 2 yrs .) (N=11)
1 . 92
0 . 17
0 . 40
0 . 73
0 . 62
0 . 11
0 . 17
Mothers with young under 2yrs . (N=8)
0 . 27
0 . 25
0
0
0 . 11
0 . 11
0 . 37
Young under 1 year (N = 6)
0
0
0
0 . 16
0 . 11
1 . 59
0
7823
7823
7823
11575
-9624
-9624
-9624
-13093
Young 1-2 yrs . (N=4)
0 . 60
0 . 08
0 . 12
No . of mins . observations, range of all aunt/infant pairs
3529
11575
11575
-6145
-13093 -13093
on the relations of the age and status of aunts to their behaviour . Females over 2 years old were divided according to whether they did or did not have infants of their own younger than two years old . The frequency of each pattern of behaviour was considered only for the age-range of the infant during which that pattern was most frequent, as indicated in Fig . 1 and Table II . The number of times which each female showed each pattern to each infant per 1,000 minutes observation over the age-range concerned was calculated, and the median values of the individual frequencies are shown in Table II . The N's in this table indicate the number of relationships in each category : clearly each infant has relationships with several aunts, and some aunts with several infants (see Table I) . For some patterns, responses of animals of both sexes under 2 years old to the infants are also included in Table II . Differences were taken as significant at P<0 .05 on a Mann & Whitney 2-tailed U test . "Tentative approaches" were made more frequently by childless females than by mothers with infants of their own or by infants of less than 1 year . The difference from infants of 1 to 2 years of age was in the same direction but not significant . "Touching", as defined above, was less frequent by young of less than l year than by females over 2 years, but otherwise differences between the groups were not significant . "Carrying/cuddling" and play were shown significantly more often by childless females than by any other category . Carrying/cuddling by aunts with infants of their own was extremely rare . When it occurred, their own infants appeared to resent it, and pushed the intruder
away . Amongst the childless females, the younger individuals tended to play more than the older (see also below) . Grooming of infants was more frequent by the childless females than by any of the other categories except I to 2 year old young, though the difference from the mothers with young was not quite significant owing to an abnormally high score by one mother . Grooming of aunts by infants was rare, and did not differ significantly between the categories of aunts . Aggression, unlike any of the other types of behaviour, was shown more frequently by mothers with young than by any of the other categories, though the difference was not significant (see above) . Aggression and play were not assessed for young under 2 years old owing to the difficulty of distinguishing between them . Amongst 1 to 2 year old animals play was the most common interaction with babies, and the 2 year old female which succeeded in stealing babies when they were too young to play, seemed to dislike their clinging and tried to push them away while trying to make them play . 3 to 4 year olds played with babies old enough to respond properly but old females only cuddled and groomed . Adult males take little part in the life of young babies . They begin to mount their daughters during the first year, the first record being at 18 weeks . A young male was mounted at 47 weeks . ii . Relative Dominance of Aunts
it was easy to assess the relative dominance of all aunts interacting with each particular infant by noting precedence at food and supplanting on perches . Whenever 2 aunts fell
ROWELL et al . : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS into the same category (Table II) for a particular infant, the frequencies with which each showed the various patterns listed in Table II were compared . Animals under 2 years old were not included . Table III shows a marked tendency for dominant aunts to interact with infants more than subordinate ones . Table III. Relation between Frequencies of Various Types of Aunt-Infant Interaction and Relative Dominance of Aunts. More dominant animal's frequency compared with that of subordinate (Greater Tentative approaches
t
Equal
Less
7
0
2
Touches
7
1
1
Carry/cuddle
5
1
3
Play
5
2
2
Aunt grooming
6
1
2
Grooms aunt
4
2
3
7
0
2
Aggression I
iii . Relationship of Aunt to Mother The aunts which showed most carrying and cuddling towards each of the first 5 infants were all subordinate to the mothers, and it appeared that mothers permitted their infants to go to subordinate females rather than dominant ones . For the 2 restricted babies, however, the reverse was the case, the adolescent taking the babies by virtue of her dominance over the mothers . Because of such complexities in the relationships between adults, we were unable to find consistent differences in the frequencies of the various behaviour patterns between dominant and subordinate aunts . High-ranking females were able to control the interaction of others with their babies by low intensity threats, and so seemed more willing to allow the interaction to be initiated . Low-ranking females tried to control interaction by grinning or presenting to dominant aunts, and only rarely by threatening them ; usually they picked up the baby and took it away . In all 6 cases where there were both dominant and subordinate aunts for one infant, the dominant aunt showed higher aggressive scores than the subordinate one . This is an indication that the mother's rank influenced the behaviour
225
of aunts to the baby from a very early age . Relative rank was not the only factor controlling the amount of interaction with a particular aunt ; indeed it is probable that its effect is exaggerated in artificially established colonies . Nearly all mothers eventually accepted one aunt with whom they were willing to leave their baby, and this was usually the female which had previously been her chief sitting and grooming companion . Sometimes other factors complicated the issue-e .g . one mother tried repeatedly, but unsuccessfully, to leave her baby with an aunt and at the same time to keep the aunt's own daughter away . In one case a mother allowed her "best friend" to hold the baby at 6 days, and thereafter the aunt often cared for the infant : this was the infant for which quantitative data were not available . The adaptiveness of this arrangement was later shown, for the mother died when the baby was 8 months old, and the aunt adopted it with minimum disturbance . (The baby never attempted to suckle from the aunt, before or after the death of its mother .) . The aunts in turn differentiated between babies of similar age, apparently on the basis of their relationship with the babies' mothersthus occasionally an aunt would break up a playfight between babies in support of their "friend's'' child . Interactions were further complicated by relationships outside the mother-infant-aunt triangle . Thus an aunt attacked by a mother might be defended by her friend, or the mother might try to re-direct the aggressiveness of a dominant aunt on to an animal inferior to both . A usually playful aunt might threaten an infant which approached when she was with the male . Discussion These observations show that, in rhesus monkeys, aunts may interact with infants in diverse ways-with maternal, aggressive, sexual, play and "social" responses . Furthermore, they influence the babies not only through direct interaction with them, but also by affecting the relation of the mother with her own infant . Whether the differences between the social environment caused by the presence of aunts have any detectable long-term effects on the characteristics of the young is a matter for further investigation . Many of the interactions between infants and adults other than their mothers which we have described could be highly adaptive in nature . The survival rate of infants would be increased if animals besides the mother protected them
226
ANIMAL BEHAVIOUR, XII,
from hazards, and if aunts were available to carry an infant whose own mother had died . There is no information on the incidence of aunt behaviour in the wild, but it is unlikely to be entirely an artifact of captivity since similar behaviour has been seen in wild langurs (Jay, 1962) and baboons (Rowell, pers . obs .) . On the other hand, the acute aunt-infant interaction which led to the mothers becoming so restrictive in Group I may well have been exacerbated by captivity . Further, the composition of artificially constructed groups differs from the natural troop ; in the latter most animals are known to each other from birth, and there is in particular the possibility of mother/daughter/grandchild/sibling relationships,which we have not yet been able to observe, and which seem to be of great importance in other species (Imanishi, 1957, 1960) for Macaca fuscata . Summary 1 . The paper is concerned with interrelations between infant rhesus monkeys, born into groups each consisting of a male, a few females and their young, with females other than their own mothers . 2. Various types of interaction are described . They include attempts to touch, carry, cuddle, mount, groom, play with and attack the infants. Most patterns were incomplete due to inferference by, or fear of, the mother . 3 . The different types of aunt-infant interaction vary in frequency with the age of the young (Fig. 1) . 4. The frequency of aunt-infant interaction is also related to the age and status of the aunt .
2- 3
Acknowledgements This work was supported by the Medical Research Council and the Mental Health Research Fund . REFERENCES Beniest-Noirot, E . (1958) . Analyse du comportement dit maternal chez la souris . Monogr . Franc. Psych ., 1, 1-114 . Dieterlin, von F. (1959) . Das Verhalten des syrischen Goldhamsters (Mesocricetus auratus Waterhouse) Z. Tierpsychol ., 16, 47-103 . Dieterlin, von F . (1962) . Geburt and Geburtshilfe bei der Stachelmaus . Z . Tierpsychol., 19, 191-222 . Harlow, H . F . (1962) . Development of the second and third affectional systems in macaque monkeys . Research Approaches to Psychiatric Problems (ed ., Tourlentes, T. T ., Pollack, S . L . & Himwick, H . E .), 209-229 . Hinde, R. A . & Rowell, T. E . (1962) . Communication by postures and facial expressions in the rhesus monkey (Macaca mulatta) . Proc . zool. Soc ., Lond., 138, 1-21 . Hinde, R . A ., Rowell, T . E . & Spencer-Booth, Y . (1964) . Behaviour of socially living rhesus monkeys in their first six months . Proc . Zool. Soc . Lond. (in press) . Imanishi, K . (1957) . Social behaviour in Japanese monkeys, Macaca fuscata . Psychologia, 1, 47-54 . Imanishi, K . (1960) . Social organisation of subhuman Primates in their natural habitat . Current Anthropol ., 1, 393-407 . Jay, P . C. (1962) . Aspects of maternal behaviour among Langurs . Proc . N. Y. Acad . Sci., 102,468-476 . Rowell, T . E . (1962) . Agonistic noises of the rhesus monkey (Macaca mulatta). Symp. zool . Soc . Lond., 8, 91-96 . Rowell, T . E . & Hinde, R . A . (1962) . Vocal communication by the rhesus monkey (Macaca mulatto) . Proc . zool. Soc . Lond ., 138, 279-294. (Accepted for publication 19th November, 1963 ; Ms . number : 422) .
Sub-Department of Animal Behaviour, Cambridge University, Madingley . are presented separately from those for the other 5 . These 2 infants lived in pen I with an adolescent female who interacted with them much more than any other aunt in the population, and repeatedly "stole" them . As a result their mothers became restrictive and some measures of their behaviour fell well outside the range for the others . For instance, these 2 babies practically never went more than 2 feet from their mothers until they were 4 to 5 months old, while the others would be spending 10 to 55 per cent. of their waking hours more than 2 feet away when this age .
Introduction Recent studies have shown that in some species of mammals "maternal" behaviour towards young is shown not only by lactating females but by nearly all older animals (e .g . Dieterlin, 1959, 1962 ; Beniest-Noirot, 1958 ; Rowell, 1962) . In man this is taken for granted ; the only other primate in which it has been described (Jay, 1962) is the langur . While studying the development of behaviour in young rhesus monkeys living in small social groups, we found that the behaviour of animals other than the mother has a profound effect on the interaction between mother and infant (Hinde, Rowell & Spencer-Booth, 1964) . Since the rest of the group forms so important a part of the environment of the developing infant, we must know what sorts of behaviour its different members show to the infant, and whether they affect its development . The influence of interaction with peers on the development of social behaviour has been shown by Harlow (1962). Here we are especially concerned with the behaviour of females other than the infant's mother and more than two years of age, which we refer to as "aunts" . Some data on interaction with males and other young are also included, but play and aggression between young are not discussed .
Aunt Behaviour a. Birth and Puerperium Early in labour the mothers usually kept away from the other animals in the group, and were ignored by them . In the 2 live births observed, however, the mother was attended closely by another female in the final stages . The other 6 babies were not seen until they were a few hours old, but in 3 of these cases an aunt was then associating closely with the mother. The attendant aunt was always childless . Four of the infants were born into groups already including infants : 2 of these mothers were attended by childless aunts, and the other 2 were unattended during the hours following birth . In some cases the placenta and birth fluids were investigated by other animals who fingered, smelled and tasted them (only nulliparous females have been observed to do this) . Those mothers who did not eat the placenta, merely dragging it behind until it dropped off, nevertheless protected it from investigating monkeys, threatening them or pulling the placenta away by the cord . At one birth 2 childless females arched their backs and fingered their own vulvae as soon as they saw the baby . In 2 cases the final stages of birth excited sexual behaviour from males : in addition one female was repeatedly mounted while her baby was still wet, and a year-old male mounted a female frequently during her puerperium . During the first day or two of its life, all animals present attempted to inspect each new baby, peering into its face and reaching to touch
Material and Methods This paper is based on observation of 8 infants throughout their first year of life . They were born into 3 groups of monkeys, each consisting of a male, 3 or 4 females, and their young. The adults had been introduced as strangers : for details see Table I . Each group was kept in an outside run, 18 feet x 10 feet x 8 feet, communicating with an inside room approximately 6 feet x 6 feet x 8 feet (see Hinde & Rowell, 1962) . The behaviour of the infants themselves is described in Hinde, Rowell & Spencer-Booth (1964) . Quantitative material was not available for the first baby, so that the figures are based on the other 7 animals . In some of the following sections quantitative data for 2 of the infants *Present address : Makerere University College, Kampala Uganda . 219
220
ANIMAL BEHAVIOUR, XII,
2 -3
Table I . Composition of Groups in which Infant-Adult Interactions Described took place . Each pen had one adult male . Female Pen I
Date introduced 8 .1 .60
8 .1 .60
Age/status at introduction 1 . Multipare
Young Y b .29.8 .60
2 . ? Nullipare d b .11 .8 .62
19 .8.60
II
3 . Nullipare c . 3 yrs .
6 .2 .61
4 . ? 10+ yrs .
14 .9 .60
1 . ? Nullipare
2 . Multipare
1 .3 .61
3 . c . 3 yrs.
Died 8.4 .61 . Dominant Y and d's favourite. Aunt to later babies . Stillbirth 25 .10.60, Adopted baby after death of mother
d b .25 .7 .62
d b .16 .4 .61 S b . 6 .6.62 25.8 .60
Remarks
Dominant Y to autumn 1962.
Dominant / from autY b .10 .4 .61 umn 1962 (d b .16 .4 .63 . Baby not included in this paper) Y b .15 .4 .62
III
1 .3 .61
4 . c . 3 yrs .
3 .11 .59
1 . Adult ? Nullipare
3.11 .59
2. Adult Nullipare
7.11 .60
3.
c. 4 yrs . Nullipare
30 .11 .60
4.
c . 3 yrs . Nullipare
29.9 .62
5 . c. 3J yrs . Nullipare
it . The mothers responded as would any rhesus with a highly desirable object-clutching the baby to them, turning their backs and threatening or hitting out at those inferior in rank . Favoured individuals were sometimes allowed to display close interest in the baby, but the mothers allowed others to huddle to them or groom them only if no obvious attention was paid to the baby .
Removed from pen 19 .2.63 . Gave birth 7 .3 .63 .
Died 12 .6 .62 (abortion) Stillbirth 24 .6 .61 . Y b .22.5 .62 Abortions 10 .4 .62 (c . 3 mths .) 14 .5.62 (c . 3 mths .) (y b .23 .3 .63 . Baby not included in this paper)
b . Interaction with Babies (i) Contact During the first few weeks after birth, aunts continued to approach the infants, examining them closely or reaching out to touch them . Their behaviour was tentative, and the mother was liable to respond aggressively to their approaches . While a baby was on its mother, the aunts often seemed to use subterfuge in order
ROWELL et al. : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS to approach it-sidling up to the mother while ostensibly foraging, or grooming her until her attention was distracted, and then surreptitiously grooming the baby until she looked again . When a baby first left its mother, other monkeys watched, motionless-at their slightest move the mother was likely to pick it up again . The babies' first attempts to crawl were directed towards nearby monkeys, and as the expeditions became more frequent and prolonged, the mothers became less protective and the aunts would edge towards the babies or reach out to touch them . These tentative approaches and touches were difficult to interpret . Usually they seemed to be attempts to groom or pick up the baby, but sometimes they appeared more aggressive . When an aunt went to a baby which was off its mother, she often crouched over it, putting her arms round it as though to pick it up, and perhaps putting her muzzle to its head . The aunt walked or climbed near the baby, hovering over it, and sometimes she actually picked it up and held it to her belly, though often it faced outwards . She then occasionally appeared to be trying to mount the infant, and made pelvic thrusts . The infants, except for the 2 restricted babies mentioned, did not cling to an aunt as for normal mother-infant carrying until they were old enough to escape and return to their mothers ; on the rare occasions when an aunt did attempt to carry them away they usually fell off and were retrieved by their mothers . Later they were sometimes carried in play (see below) . Adult animals showed the same play patterns with babies as Harlow (loc . cit .) has described for infant-infant interactions . However, rough-and-tumble was not as common as preliminary enticement gestures-crouching chest to ground with mouth open, or tugging gently at the babies' arms . Older aunts especially included cuddling and mounting in play with babies, and seemed more gentle in their movements than is usual in infant-infant play . ii . Communication The noises and gestures referred to in this section are described in Hinde & Rowell (1962), Rowell & Hinde (1962) and Rowell (1962). Aunts sitting watching babies made short series of coughing grunts, at the same time bobbing their heads and wagging their tails . They did this especially when a baby first set out from its mother to explore, or when it re-
221
turned to her after exploring . Females in other cages would sometimes line the wire to watch a baby, cough-grunting as they did so . Mothers made no apparent response to cough-grunting aunts, but babies would occasionally approach them . The cough-grunt was restricted to the situation described, except for a single occasion when an aunt cough-grunted to a female in labour . Aunts often lip-smacked to a baby when it was facing towards them, and they sometimes presented their hindquarters . The latter response was given both to mother and baby during the first few days of life, and later to infants away from their mothers . The younger babies did not respond, but older ones often stood up to sniff at the aunt's rump, and by 6 months they would sometimes attempt to groom or mount in adult fashion . Aunts also presented to the mother when they had frightened a baby, or when the mother was beginning to stop the aunt interacting with her baby . Infants also occasionally presented to aunts, the earliest record being in week 16 . This became more common after the end of the first year . Aunts responded to many of the noises and gestures made by the babies . Cries of fear were nearly always reacted to instantly by the mother going to the baby, but aunts often started towards it as well, and cough-grunted loudly when the mother rescued it . As the babies began to develop adult communication patterns, such as greeting growls or soliciting-for-grooming postures, the aunts responded appropriately, often making loud "pleasure noises" themselves . iii . Protection Aunts attendant on a newly parturient mother threatened other animals in the group, Males, too, were more than usually protective to new mothers, and in some cases defended them from females which they normally supported . As the infants grew, aunts sometimes watched them when they tried new physical feats and hovered anxiously nearby, going to the rescue if necessary . They seemed to be aware of dangers to young infants-for instance showing care when using the heavy swing door connecting the two parts of the pen if babies were near, and occasionally holding it open for an infant to scramble through . When a baby approached the observer an aunt would sometimes threaten, with the result that the baby went away, and on a few occasions an aunt punished another female
222
ANIMAL BEHAVIOUR, XII, 2- 3
who had been aggressive to a baby . Occasionally a baby rejected by its mother would go to an aunt and be cuddled . Some mothers used aunts as "baby-minders", leaving their baby near an aunt while they foraged . Most of the time, however, the infants were in close touch with their mother and protection by aunts was more a constant possibility than a frequent occurrence . iv . Aggression
descriptively and functionally distinct follow each other rapidly, so that the animal's behaviour appears to be highly ambivalent . In addition the pattern of interaction between an adultinfant pair changes from week to week as the baby develops ; and each mother-infant-aunt relationship has its own characteristics, depending on the history and composition of the group . In the next section some of these variations are
I.
Older babies were often a nuisance to aunts in their play, jumping over them or colliding with them . On the whole, the aunts were tolerant of such behaviour-perhaps because they were afraid of retaliation from the mother . Sometimes, however, and especially when the mother was some distance away, the baby was cuffed, bitten gently or threatened, always with one eye on the mother . Mothers were often aggressive to infants playing with their own, and drove them away if play became rough . They always drove off a baby that tried to play with their own when it was suckling or sleeping . The aggressive actions of some aunts seemed to be un- Fig. 1 . Change in incidence of various types of aunt-infant interaction with age related to the infant's behav- of infant . iour, and should perhaps be in- Ordinates indicate mean number of records per 100 minutes observation . Abscissa 6 hours a week for terpreted as an expression of the indicates age of infant : each infant was watched for at; least first six weeks, and 6 hours a fortnight thereafter the data were lumped by aunt's dominance . For instance, the fortnights for the first 6 weeks and then by months . one aunt, herself a mother, In (a) to (e) the thick line refers to the five "normal" young and the discontinwould sometimes pull and tweek uous line to the two restricted young . In (f) the aggressive responses made to the five young by aunts with infants of less than one year of their own (dotted at the 2 other babies born into first have been separated from those made by aunts without such infants (thick her group while they were on lines) line) . their own mothers . Males punished irritating babies by holding analysed. them down to the ground with one hand, and Variations in Aunt/Infant Interaction sometimes mouthing them gently, for a few (a) Age of Baby seconds . The frequencies of the various behaviour patterns shown by the aunts to the babies v . General changed as the babies grew . The changes for 5 In the preceding sections we have described of the babies are illustrated by the thick lines a number of patterns of behaviour shown by in Fig . 1, and the 2 restricted babies by the disolder rhesus monkeys towards infants. One of continuous lines (see legend to figure for conthe most striking characteristics of "aunt" beventions used in (f) . The numbers of animals haviour, however, is that patterns which are (a)
TENTATIVE APPROACHES
01
I/7
4157
WEEKS
WEEKS
ROWELL et al . : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS
from which these data were derived are small, but certain differences between the variations of the several patterns with age of infant are suggested . In the first 5 infants tentative approaches (Fig . la) were common in the first 2 to 3 weeks, but stopped by about 5 months . Brief touches (Fig . lb) were rare in the first week, became commonest in weeks 3 to 10, and ceased by the end of the year . Grooming (Fig . lc) became common after the fifth week, and was especially so in weeks 15 to 30 . Grooming of aunts by infants started later, and in the first year was common in weeks 30 to 40. Carrying and cuddling by aunts (Fig . ld) increased up to 10 to 13 weeks and then fell to a low level . It was usually associated with touching, grooming, etc . Towards the end of the year carrying again increased, but was then associated mainly with play . Play invitations (Fig. le) rose to a peak: in the third month, and then decreased . Aggression by childless aunts (Fig . If, thick line) began at about 12 weeks, and became more frequent during the fourth month . For individual babies, aggression began at different ages, between 12 and 18 weeks . The babies' mothers became aggressive or began to reject the baby at about the same time as its aunts became aggressive, or slightly earlier . Aunts with their own young (Fig . If, dotted line) were more frequently aggressive to young babies, especially in the second month . The drop in their aggressiveness at about 12 weeks may be related to decreasing protectiveness towards their own babies, rather than to the age of the attacked infant ; because births mainly occurred within a restricted breeding season, young babies tended to have aunts with young babies, and we were not able to separate these effects . The frequencies of tentative approaches and brief touches for the 2 restricted babies were similar to those for the other 5 . The frequencies of grooming and carry/cuddling were on average greater throughout, due to the activity of the female whose attentions made the mother restrictive .* The peaks of grooming, carry/ The frequency of grooming for one of the two-restricted babies was greater than that for all the others in 11 out of 13 periods in which any infant was groomed (see Fig . 1), and greater than that for 4 of them in the other 2 periods . The frequency for the other restricted baby was greater than at least 4 of the others in 9 out of these periods . The frequency of carry/cuddling for one of the restricted babies was greater than that for any other baby in 9 of the 10 periods after weeks 11 to 14 . The frequency of the other was equal to or greater than at least 4 of the non-restricted babies in 8 out of these 9 periods .
223
cuddling, play and aggression were all later than for the non-restricted infants . It will be seen that the various types of auntinfant interaction have different time courses in relation to the infant's age . The changes in response frequencies can be related partly to changes in the behaviour of the babies as they develop locomotor skills (see Hinde, Rowell & Spencer-Booth, 1964) . Thus tentative approaches were commonest when the babies were spending most of their time on their mothers, and the frequency of brief touches parallels the proportion of time the baby spent within 2 feet of its mother . Carrying/cuddling, play and grooming all increased with the amount of time the baby spent away from its mother, and therefore was available for interaction . Grooming increased especially at the time the babies began to make grooming-invitation postures (10 to 14 weeks) . These complementary changes in aunt behaviour and babies' behaviour also occurred for the two restricted babies although much later in the lives of the babies because of the restrictiveness of the mothers . The 5 "normal" babies had acquired most of their skills by the end of the third month, and the time they spent away from their mothers, after a rapid increase in the second and third months, increased only slowly up to 6 months . The frequency of some of the aunts' responses, however, changed markedly during the fourth and fifth month ; in particular the activities by which the aunts made contact with the babies decreased, and grooming, which is the behaviour typical of adult "friendly" interaction, increased . During this period the appearance of the baby changes . The new-born rhesus has a very soft coat, rather like thin-pile velvet . On its head there are two tufts of hair, separated by a centre parting . This coat is replaced at five months by a thicker one . The centre parting is lost, and the head comes to look round . (This juvenile fur is replaced by the adult grey and brown coat at just over a year .) The change in appearance and texture is gradual, but begins to be apparent at about 12 weeks . It is possible that the characteristics of the young babies may play an important part in eliciting attempts to make contact by adults . b . Difference Between Aunts i . Age and Reproductive Status
The behaviour patterns described in the preceding sections were not shown equally often by all aunts . We may now consider some data
224
ANIMAL BEHAVIOUR, XII,
2 -3
Table IL Frequency of Interaction Between Aunts and Infants when Infants were in the Age-ranges Shown, expressed as the
Median Number of Records per 1000 Minutes Observation . i Tentative Carry/ Aunt approach Touch cuddle Play grooming
Grooms aunt Aggression
Weeks over which assessed
1-14
3-52
3-52
9-44
9-44
9-44
3-52
Childless females (over 2 yrs .) (N=11)
1 . 92
0 . 17
0 . 40
0 . 73
0 . 62
0 . 11
0 . 17
Mothers with young under 2yrs . (N=8)
0 . 27
0 . 25
0
0
0 . 11
0 . 11
0 . 37
Young under 1 year (N = 6)
0
0
0
0 . 16
0 . 11
1 . 59
0
7823
7823
7823
11575
-9624
-9624
-9624
-13093
Young 1-2 yrs . (N=4)
0 . 60
0 . 08
0 . 12
No . of mins . observations, range of all aunt/infant pairs
3529
11575
11575
-6145
-13093 -13093
on the relations of the age and status of aunts to their behaviour . Females over 2 years old were divided according to whether they did or did not have infants of their own younger than two years old . The frequency of each pattern of behaviour was considered only for the age-range of the infant during which that pattern was most frequent, as indicated in Fig . 1 and Table II . The number of times which each female showed each pattern to each infant per 1,000 minutes observation over the age-range concerned was calculated, and the median values of the individual frequencies are shown in Table II . The N's in this table indicate the number of relationships in each category : clearly each infant has relationships with several aunts, and some aunts with several infants (see Table I) . For some patterns, responses of animals of both sexes under 2 years old to the infants are also included in Table II . Differences were taken as significant at P<0 .05 on a Mann & Whitney 2-tailed U test . "Tentative approaches" were made more frequently by childless females than by mothers with infants of their own or by infants of less than 1 year . The difference from infants of 1 to 2 years of age was in the same direction but not significant . "Touching", as defined above, was less frequent by young of less than l year than by females over 2 years, but otherwise differences between the groups were not significant . "Carrying/cuddling" and play were shown significantly more often by childless females than by any other category . Carrying/cuddling by aunts with infants of their own was extremely rare . When it occurred, their own infants appeared to resent it, and pushed the intruder
away . Amongst the childless females, the younger individuals tended to play more than the older (see also below) . Grooming of infants was more frequent by the childless females than by any of the other categories except I to 2 year old young, though the difference from the mothers with young was not quite significant owing to an abnormally high score by one mother . Grooming of aunts by infants was rare, and did not differ significantly between the categories of aunts . Aggression, unlike any of the other types of behaviour, was shown more frequently by mothers with young than by any of the other categories, though the difference was not significant (see above) . Aggression and play were not assessed for young under 2 years old owing to the difficulty of distinguishing between them . Amongst 1 to 2 year old animals play was the most common interaction with babies, and the 2 year old female which succeeded in stealing babies when they were too young to play, seemed to dislike their clinging and tried to push them away while trying to make them play . 3 to 4 year olds played with babies old enough to respond properly but old females only cuddled and groomed . Adult males take little part in the life of young babies . They begin to mount their daughters during the first year, the first record being at 18 weeks . A young male was mounted at 47 weeks . ii . Relative Dominance of Aunts
it was easy to assess the relative dominance of all aunts interacting with each particular infant by noting precedence at food and supplanting on perches . Whenever 2 aunts fell
ROWELL et al . : "AUNT"-INFANT INTERACTION IN CAPTIVE RHESUS MONKEYS into the same category (Table II) for a particular infant, the frequencies with which each showed the various patterns listed in Table II were compared . Animals under 2 years old were not included . Table III shows a marked tendency for dominant aunts to interact with infants more than subordinate ones . Table III. Relation between Frequencies of Various Types of Aunt-Infant Interaction and Relative Dominance of Aunts. More dominant animal's frequency compared with that of subordinate (Greater Tentative approaches
t
Equal
Less
7
0
2
Touches
7
1
1
Carry/cuddle
5
1
3
Play
5
2
2
Aunt grooming
6
1
2
Grooms aunt
4
2
3
7
0
2
Aggression I
iii . Relationship of Aunt to Mother The aunts which showed most carrying and cuddling towards each of the first 5 infants were all subordinate to the mothers, and it appeared that mothers permitted their infants to go to subordinate females rather than dominant ones . For the 2 restricted babies, however, the reverse was the case, the adolescent taking the babies by virtue of her dominance over the mothers . Because of such complexities in the relationships between adults, we were unable to find consistent differences in the frequencies of the various behaviour patterns between dominant and subordinate aunts . High-ranking females were able to control the interaction of others with their babies by low intensity threats, and so seemed more willing to allow the interaction to be initiated . Low-ranking females tried to control interaction by grinning or presenting to dominant aunts, and only rarely by threatening them ; usually they picked up the baby and took it away . In all 6 cases where there were both dominant and subordinate aunts for one infant, the dominant aunt showed higher aggressive scores than the subordinate one . This is an indication that the mother's rank influenced the behaviour
225
of aunts to the baby from a very early age . Relative rank was not the only factor controlling the amount of interaction with a particular aunt ; indeed it is probable that its effect is exaggerated in artificially established colonies . Nearly all mothers eventually accepted one aunt with whom they were willing to leave their baby, and this was usually the female which had previously been her chief sitting and grooming companion . Sometimes other factors complicated the issue-e .g . one mother tried repeatedly, but unsuccessfully, to leave her baby with an aunt and at the same time to keep the aunt's own daughter away . In one case a mother allowed her "best friend" to hold the baby at 6 days, and thereafter the aunt often cared for the infant : this was the infant for which quantitative data were not available . The adaptiveness of this arrangement was later shown, for the mother died when the baby was 8 months old, and the aunt adopted it with minimum disturbance . (The baby never attempted to suckle from the aunt, before or after the death of its mother .) . The aunts in turn differentiated between babies of similar age, apparently on the basis of their relationship with the babies' mothersthus occasionally an aunt would break up a playfight between babies in support of their "friend's'' child . Interactions were further complicated by relationships outside the mother-infant-aunt triangle . Thus an aunt attacked by a mother might be defended by her friend, or the mother might try to re-direct the aggressiveness of a dominant aunt on to an animal inferior to both . A usually playful aunt might threaten an infant which approached when she was with the male . Discussion These observations show that, in rhesus monkeys, aunts may interact with infants in diverse ways-with maternal, aggressive, sexual, play and "social" responses . Furthermore, they influence the babies not only through direct interaction with them, but also by affecting the relation of the mother with her own infant . Whether the differences between the social environment caused by the presence of aunts have any detectable long-term effects on the characteristics of the young is a matter for further investigation . Many of the interactions between infants and adults other than their mothers which we have described could be highly adaptive in nature . The survival rate of infants would be increased if animals besides the mother protected them
226
ANIMAL BEHAVIOUR, XII,
from hazards, and if aunts were available to carry an infant whose own mother had died . There is no information on the incidence of aunt behaviour in the wild, but it is unlikely to be entirely an artifact of captivity since similar behaviour has been seen in wild langurs (Jay, 1962) and baboons (Rowell, pers . obs .) . On the other hand, the acute aunt-infant interaction which led to the mothers becoming so restrictive in Group I may well have been exacerbated by captivity . Further, the composition of artificially constructed groups differs from the natural troop ; in the latter most animals are known to each other from birth, and there is in particular the possibility of mother/daughter/grandchild/sibling relationships,which we have not yet been able to observe, and which seem to be of great importance in other species (Imanishi, 1957, 1960) for Macaca fuscata . Summary 1 . The paper is concerned with interrelations between infant rhesus monkeys, born into groups each consisting of a male, a few females and their young, with females other than their own mothers . 2. Various types of interaction are described . They include attempts to touch, carry, cuddle, mount, groom, play with and attack the infants. Most patterns were incomplete due to inferference by, or fear of, the mother . 3 . The different types of aunt-infant interaction vary in frequency with the age of the young (Fig. 1) . 4. The frequency of aunt-infant interaction is also related to the age and status of the aunt .
2- 3
Acknowledgements This work was supported by the Medical Research Council and the Mental Health Research Fund . REFERENCES Beniest-Noirot, E . (1958) . Analyse du comportement dit maternal chez la souris . Monogr . Franc. Psych ., 1, 1-114 . Dieterlin, von F. (1959) . Das Verhalten des syrischen Goldhamsters (Mesocricetus auratus Waterhouse) Z. Tierpsychol ., 16, 47-103 . Dieterlin, von F . (1962) . Geburt and Geburtshilfe bei der Stachelmaus . Z . Tierpsychol., 19, 191-222 . Harlow, H . F . (1962) . Development of the second and third affectional systems in macaque monkeys . Research Approaches to Psychiatric Problems (ed ., Tourlentes, T. T ., Pollack, S . L . & Himwick, H . E .), 209-229 . Hinde, R. A . & Rowell, T. E . (1962) . Communication by postures and facial expressions in the rhesus monkey (Macaca mulatta) . Proc . zool. Soc ., Lond., 138, 1-21 . Hinde, R . A ., Rowell, T . E . & Spencer-Booth, Y . (1964) . Behaviour of socially living rhesus monkeys in their first six months . Proc . Zool. Soc . Lond. (in press) . Imanishi, K . (1957) . Social behaviour in Japanese monkeys, Macaca fuscata . Psychologia, 1, 47-54 . Imanishi, K . (1960) . Social organisation of subhuman Primates in their natural habitat . Current Anthropol ., 1, 393-407 . Jay, P . C. (1962) . Aspects of maternal behaviour among Langurs . Proc . N. Y. Acad . Sci., 102,468-476 . Rowell, T . E . (1962) . Agonistic noises of the rhesus monkey (Macaca mulatta). Symp. zool . Soc . Lond., 8, 91-96 . Rowell, T . E . & Hinde, R . A . (1962) . Vocal communication by the rhesus monkey (Macaca mulatto) . Proc . zool. Soc . Lond ., 138, 279-294. (Accepted for publication 19th November, 1963 ; Ms . number : 422) .