Social behavior in aged rhesus macaques

This study investigated the relationship between chronological age and social behavior in 42 adult male and female rhesus macaques (Macaca mulatta) in three specific areas: social interactions, social roles, and social networks. While both old males and old females share behavioral differences associated with senescence, this study reports that old females and old males are distinct in their social behaviors, both from each other and from other adults. Many of these differences appear progressive across age classes, e.g., declining across age classes in females and increasing across age classes in males. Old females are less social and have smaller social networks than other females, while the opposite was found to be true of old males. An explanation for the sex-based differences in aged social behavior and social networks reported in this study may originate in rhesus matrifocal social structure.     

Male competition and its hormonal correlates in Assamese macaques (Macaca assamensis)

In polygynous mammals, where males compete over access to females, the potential of males to monopolize reproductive females largely depends on the spatio-temporal distribution of reproductive females. We investigated mechanisms of male reproductive competition and its hormonal basis in a cercopithecine species with reduced contest potential owing to female reproductive synchrony and concealed ovulation. Over 16 months including two mating seasons we collected 1218 h of observational focal animal data and 1254 fecal samples of 11-12 adult and large subadult male Assamese macaques (Macaca assamensis) living in their natural habitat in Thailand. Androgen output along with aggressive behavior showed a seasonal pattern, with highest values being obtained by all males during the mating season and by those males experiencing acute social challenges, e.g. rank change and dispersal. Individual androgen levels and rates of attacks were linked across the study period, suggesting a promoting function of androgens for aggressive behavior. Dominance rank predicted neither mating success nor androgen levels consistently, indicating a reduced selective advantage of high social status for general mating access. However, high ranking males engaged in extended consortships with reproductive females. Distribution of consortships across males followed a priority of access distribution, with the two top ranking males accounting for 75% of consort activity, suggesting that high social status also carries fitness benefits in a species characterized by low contest potential.     

A review of hormonal factors influencing the sexual and aggressive behavior of macaques

The effects of gonadal hormones on the sexual and aggressive behavior of adult macaques are reviewed. Similarities among findings from field, colony, and laboratory studies strengthen the view that testosterone facilitates the sexual and aggressive behavior of males, while sexual and perhaps aggressive behavior by the female is mainly dependent on estradiol, which increases both the sexual motivation of the female and her attractiveness to males. Differences between results from different settings help to emphasize the role of environmental and social factors in modulating the effects of hormones. © 1993 Wiley-Liss, Inc.     

Puberty in male Japanese macaques (Macaca fuscata): Social and sexual behavior in a confined troop

The social and sexual behaviors of four groups of males (4, 5, 9, and 10 years old) were compared throughout one complete mating season in a confined troop of Japanese macaques (Macaca fuscata). The aim of this research was to document social behavior changes that occurred during adolescence and to relate them to changes in sexual behavior that occurred at puberty. The 4-year-old males all mounted females and ejaculated but they had significantly fewer ejaculations and female partners than did the older males. The 4-year-old males also showed a pattern of delayed development in tail carriage and courtship, and they played more frequently than the older males. There were no significant differences in the frequency of aggression among the groups, but both 4-year-old and 5-year-old males were displaced by adult males and females more frequently than were the older males. We concluded that the development of adult patterns of social behavior in this genus is not climactic, but occurs slowly one to two years after physiological puberty has been reached.     

Suspensory behavior and its role in positional activities of Japanese macaques

Suspensory behavior of free-ranging Japanese macaques was classified based on the kinematics and situations, and incidence of the behavior recorded with the continuous focal animal sampling method was compared between different age groups. Of all age groups, infants used the various types of suspension most frequently, and the frequency declined rapidly with age. Suspension was used as 1) a safety device by infants, to prevent falling down from supports when losing balance, 2) a feeding posture and 3) a supplement for shortage of the reaching length composed of limbs and trunk lengths in young macaques. The roles of suspensory behavior in the development of positional activities in Japanese macaques are briefly discussed.     

Experiential and hormonal correlates of maternal behavior in teen and adult mothers

This study explores the role of cortisol and early life experiences in the regulation of maternal behavior and mood in teen and adult mothers. Primiparous mothers (n=119) (teen mothers < 19 years, n=42), young mothers (19-25 years, n= 4), and mature mothers, (>25 years, n=43) were assessed for their maternal behavior, mood, and hormonal profile at approximately 6 weeks postpartum. Outcome measures were analyzed as a function of age and early life experience. Results showed an interaction between age and type of maternal behavior, where teen mothers engaged in more instrumental (e.g. changing diapers, adjusting clothes) less affectionate (e.g., stroking, kissing, patting) behavior, and mature mothers engaged in more affectionate and less instrumental behavior. When groups were reassessed based on early life experience (consistency of care during the first 12 years of life: consistent care; having at least one consistent caregiver, inconsistent care; having multiple and changing caregivers), an interaction was also found between consistency of care and type of behavior shown, where mothers who received inconsistent care engaged in more instrumental and less affectionate behavior. Compared to mature mothers, teen mothers who were breast feeding also had higher salivary cortisol levels, and high cortisol in teen mothers related to decreased fatigue and increased energy. These results suggest that early life experiences are linked to mothering behavior and are consistent with the emerging human and animal literature on intergenerational effects of mothering style.     

Development of intervention behavior in Japanese macaques: Testing the targeting hypothesis

Matrilineal dominance systems, which characterize several species of cercopithecines, are determined largely by the patterning of third-party aggressive interventions in conflicts. Although the role of interventions in structuring rank relations has received much attention, very few studies have dealt specifically with the development of intervention behavior. In other words,most studies have focused on the interventions received and their effect on the recipients rather than on the interventions performed and the goals of the interveners. We analyzed the intervention behavior of 10 juvenile females in a colony of 40 Japanese macaques (Macaca fuscata)housed at the University of Montreal Laboratory of Behavioral Primatology. The analysis of 749 interventions performed by the juveniles over their first 4 years and 2425 interventions received over the same period reveals that (1) juvenile females intervened selectively against females ranking below their mother, (2) they began to intervene at about the same time that they began to challenge the latter females in dyadic contests, (3) they sided with females as well as with males against these females, (4) juvenile interveners incurred little risks in terms of aggressive retaliation from their targets, (5) they derived immediate benefits in terms of conflicts won over stronger targets, (6) interventions often did not take place when the possible recipients needed support, and (7) interveners did not conform to a pattern of mutually preferential support. These results support the view that interventions by juveniles are selfish (vs altruistic) and constitute a low-cost and effective means to target and to outrank prospectively subordinate females.     

Induction of maternal behavior and some hormonal and physiological correlates in the domestic hen

The manifestation of maternal behavior and the variations of plasmatic levels of gonadic hormones (testosterone, delta 4-androstenedione, and 17 beta-estradiol) have been studied in two groups of domestic hens (layers and nonlayers) during a forced adoption experiment. Maternal behavior appears later in actively laying hens than in nonlayers. The former hens show a higher level of androgens (T and delta 4). The appearance of typical maternal behavior coincides with a pause in laying and a decrease in all the plasmatic steroid levels measured.     

Courtship behaviour in Japanese macaques during heterosexual and homosexual consortships

Female Japanese macaques (Macaca fuscata) in the Arashiyama population near Kyoto, Japan, are unusual, in that they exhibit what many would consider to be male-typical sexual characteristics. Specifically, they mount other females within the context of temporary, but exclusive, sexual relationships (i.e., homosexual consortships) and they sometimes exhibit a preference for female sexual partners, even when given the choice of a sexually motivated male alternative. In this study, we examined whether female Japanese macaques also exhibited male-typical patterns of courtship behaviour during homosexual consortships. Data were collected on courtship behaviour during heterosexual and homosexual consortships in free-ranging Japanese macaques from the Arashiyama (Japan) population. We analyzed the occurrence of 12 different courtship behaviours during 3374 heterosexual inter-mount intervals and 1412 homosexual inter-mount intervals. Sex differences between heterosexually consorting males and females existed for only two of the 12 courtship behaviours we investigated: inclined-back presentations and sexual vocalizations. Dominant and subordinate homosexually consorting females were sex-typical in their expression of inclined-back presentations and sexual vocalizations. Consequently, facultative same-sex sexual partner preference, mounting and consortships do not co-occur with male-typical patterns of courtship behaviour in female Japanese macaques.     

Play behavior in immature moor macaques (Macaca maura) and Japanese macaques (Macaca fuscata)

Play is widespread across mammalian taxa, but species strongly vary in the ways they play. In less despotic primate species (i.e., with less steep dominance hierarchies, less severe conflicts, and more reconciliation), play has been described as being more frequent, cooperative, and freely expressed. To study the link between social play and dominance style, we compared play behavior in free-ranging infants, juveniles and subadults of more despotic Japanese macaques (Macaca fuscata, N = 24) and less despotic moor macaques (Macaca maura, N = 17). We found interspecific differences in play behavior that corresponded with the contrasting dominance styles of the study species, largely confirming our predictions. In particular, moor macaques spent a larger proportion of time in solitary and social play than Japanese macaques, while Japanese macaques spent a larger proportion of time in grooming interactions. In moor macaques, play sessions included more players, a larger variety of play behaviors, greater play face rates, a greater proportion of time in contact play, and a higher rate of reciprocal play-biting than in Japanese macaques. Aggressive escalations were not common, but more frequent in Japanese macaques. Finally, a higher frequency of play faces during play sessions predicted the occurrence of more reciprocal play-bites, but not the proportion of time spent in contact play behaviors. Additional studies on other groups and species will allow a better understanding of the link between dominance style and social play.     

Performance correlates of social behavior and organization: Social rank and reversal learning in crab-eating macaques (M. fascicularis)

Seventeen male crab-eating macaques drawn from two captive troops, were tested on a brightness discrimination, reversal learning task. Fourteen of these animals completed ten reversals. It was found that the performance of the three highest ranking animals from each troop, taken together, was poorer than that of the lower ranking animals that were tested. The high ranking animals made more errors before reaching criterion on both initial learning and the reversal problems. Analysis of error patterns revealed that, while the high ranking animals had no more difficulty than the others in withholding their responses to the previously correct stimulus following reversals, they did not adopt the correct strategy as soon as the low ranking animals. The results have been interpreted in terms of a carry-over of a hypothetical factor or factors resulting from pressures created by the ongoing social dynamics involved in establishing and maintaining a given social rank at the time laboratory testing occurred. Supported by USAMRDC Contract No. DADA 17-73-C-3007.     

Parity-related differences in suckling behavior and nipple preference among free-ranging Japanese macaques

Suckling behavior of primiparae in free-ranging Japanese macaques (Macaca fuscata) was compared with that of multiparae at Jigokudani Monkey Park, the Shiga Heights, Nagano Prefecture, Japan, from April 1984 to June 1994. The estimated rates of milk secretion in a single preferred nipple among primiparae were lower than those among multiparae from birth to 5 months of age. Milk secretion capabilities of primiparous mothers, hence, appear to be inferior to those of multiparous mothers. In nutritive sucking, although Japanese macaque infants preferred one single nipple, nipple preferences in primiparae were weaker than those in multiparae. With supplementary two-nipple use during sucking, however, the infants of primiparae appear to overcome a suckling flaw of their primiparous mothers. After infants were 5 months of age and after a drop (from approximately 10% to approximately 5%) in the rates of milk secretion, however, milk secretion rates in a single preferred nipple among primiparae were similar to those in multiparae and the supplementary two-nipple use in primiparous mother-infant dyads disappeared. Am. J. Primatol. 42:331–339, 1997. © 1997 Wiley-Liss, Inc.     

Development in Japanese macaques (Macaca fuscata): Sexually dimorphic behavior during the first year of life

We have documented several sexually dimorphic patterns of behavior that develop during the first year of life in infant Japanese macaques and their mothers. Mothers treated their infants differently by sex—mothers of males broke contact with them and retrieved them more frequently than did mothers of females. And mothers of male infants moved more frequently than did mothers of female infants. Male infants played more, played in larger groups, and mounted more frequently; female infants groomed and spent more time close to other monkeys in larger social groups than did males. Female infants were also punished by other group members more frequently than were male infants. We conclude that male and female Japanese macaque infants receive differential treatment early in life by both their own mothers and other animals, and males and females in turn treat their mothers and other animals differently. There appears to be a reciprocal relationship between the behavior of infants, mothers and other social partners that contributes to the development of sexually dimorphic patterns of behavior.     

Osteocalcin is vitamin D-dependent during the perinatal period in the rat

The vitamin D-dependence of renal calbindin D-28K and osteocalcin during the perinatal period was studied in fetuses (days 18 and 21) and neonates (days 2, 12, 17 and 22) of rats fed either a standard diet (0.85% Ca-0.7% P; "high Ca-P diet" rats) or a mildly Ca-P restricted diet (0.2% Ca-0.2% P; "low Ca-P diet" rats). Body weight and plasma calcium levels were identical in both groups. Plasma 1,25(OH)2D concentrations were markedly higher in the low Ca-P diet rats at all stages of fetal and neonatal life (in 22-day-old neonates: 536 +/- 58 pg/ml versus 126 +/- 12 pg/ml). 1,25(OH)2D concentrations increased between day 18 and 21 of fetal life, remained constant between day 21 of fetal and day 12 of neonatal life, and increased sharply between day 12 and 17 in both groups; after day 17, 1,25(OH)2D concentrations increased further in pups fed the low Ca-P diet. Renal calbindin D-28K reached peak concentrations on day 12 of neonatal life; calbindin D-28K levels were similar in the high and low Ca-P diet rats at all stages of perinatal development. Plasma osteocalcin levels increased steadily during the perinatal period; at most stages of perinatal life, and already from the fetal period was osteocalcin higher in the low Ca-P diet rats than in the high Ca-P diet rats (in 22-day-old pups: 1106 +/- 47 ng/ml versus 429 +/- 14 ng/ml). Femoral osteocalcin concentrations were also increased in fetal and early neonatal (days 2 and 12) low Ca-P diet rats, while the femoral calcium content and concentration of these rats were decreased in the late neonatal period (days 12, 17 and 22). These studies indicate that osteocalcin is vitamin D-dependent in the fetal and neonatal rat.     

Mitochondrial oxidative phosphorylation in the rat kidney during the perinatal period

Oxidative metabolism in the developing rat kidney has been studied on isolated mitochondria. An increase of about 50% in state 3 respiration has been observed at birth, using succinate, glutamate, or palmitoyl-L-carnitine as a substrate. The rate of respiration in the presence of 2,4-dinitrophenol was found identical to state 3 respiration in all cases. Cytochrome oxidase activity did not change between the fetal and newborn stages. The increase of mitochondrial respiration revealed here, which is not linked to a modification of the respiratory chain, could be involved in the rise of kidney ATP level and energy charge observed at birth.