Enhancement of attachment and cognitive development of young nursery-reared chimpanzees in responsive versus standard care

The Lasting Impact of Social Isolation: Behavioral Insights From Former Pet and Entertainer Chimpanzees in a Sanctuary in Spain

Human fascination with chimpanzees has driven extensive research on the species, but also led to exploitation by private owners and entertainment industries. These animals often suffer species-specific inadequate conditions, which can result in the development and display of abnormal behaviors even after rescue. These behaviors highlight the importance for zoos and sanctuaries to actively prevent worsening the effects of previous inadequate treatment by providing apes with social and stimulating environments that support their recovery. We conducted a 2-month behavioral survey on two groups of former pet and entertainment chimpanzees (n = 10) at the Fundación MONA sanctuary in Spain. From 116 h of instantaneous scan observations, we documented individual abnormal behaviors (e.g., self-poking, overgrooming, self-scratching). We assessed the association between the occurrence of these behaviors and individuals' origin, early history, age at rescue, and pre-rescue social conditions. We found no significant difference in the frequency of abnormal behavior between pet and entertainer chimpanzees, and between individuals born in captivity versus in the wild. Moreover, we observed that the frequency of abnormal behaviors increased with age at rescue for previously isolated individuals, but the correlation disappeared for those socially housed pre-rescue. These findings suggest that early social isolation and a late age at rescue may impose long-term changes on chimpanzees' behavior, and they emphasize the importance of accounting for age at rescue and previous housing conditions in care management and rehabilitation procedures.

The Development of Feeding Competence in Rehabilitant Orphaned Orangutans and How to Measure It

For critically endangered species, restorative conservation becomes increasingly important. Successful re-introduction of rescued wild orangutan orphans requires rehabilitation mimicking maternal rearing in the wild. Feeding competence-what to eat, where and when to find food-needs to be learned before re-introduction. We observed seven orphans (2-10 years old) for a period of 3 years during their rehabilitation at the Yayasan Jejak Pulang forest school. Of the 111 plant genera eaten by the orphans, 92 percent were known orangutan food plants. Five plant genera were eaten by all orphans in over 90 percent of the months within the observation period. The Fruit Availability Index (FAI) was used to predict which parts of a plant were consumed by the orphans. We found that the orphans ate primarily fruit when the FAI was high, but consumed more young leaves, cambium, and pith when FAI was low. Thus, the orphans exhibited food choices very similar to mature wild orangutans and appropriate to forest productivity. The orphans' acquisition of feeding competence was facilitated by their immersion into a natural forest environment in combination with possibilities for observational learning from conspecifics as well as caregivers modelling food processing and consumption.

Early Trauma Leaves No Social Signature in Sanctuary-Housed Chimpanzees (Pan troglodytes)

Negative early experiences can have detrimental effects on social functioning in later life, both in humans as well as in other socially-living animals. In zoo-housed chimpanzees, recent evidence suggests that there may be a lingering signature of early trauma on individuals' social interaction tendencies as measured by social proximity and grooming. Here, we address whether a similar effect would be observable in chimpanzees living under semi-wild conditions in an African sanctuary. By analysing party size, close proximity and social grooming, we show that in this specific sanctuary, chimpanzees that suffered early trauma (n = 42) were socially indistinguishable from chimpanzees who were born and raised by their mothers in the sanctuary (n = 36). Our findings indicate that chimpanzees may not be irreversibly affected by early social trauma, possibly owing to rehabilitation in stable social groups in a semi-natural environment. Beyond identifying sanctuaries as valuable rehabilitation centres for orphaned chimpanzees, this study demonstrates a remarkable social flexibility in one of our closest living relatives.

Joint Attention in Human and Chimpanzee Infants in Varied Socio-Ecological Contexts

Joint attention (JA) is an early manifestation of social cognition, commonly described as interactions in which an infant looks or gestures to an adult female to share attention about an object, within a positive emotional atmosphere. We label this description the JA phenotype. We argue that characterizing JA in this way reflects unexamined assumptions which are, in part, due to past developmental researchers' primary focus on western, middle-class infants and families. We describe a range of cultural variations in caregiving practices, socialization goals, and parenting ethnotheories as an essential initial step in viewing joint attention within inclusive and contextualized perspectives. We begin the process of conducting a decolonized study of JA by considering the core construct of joint attention (i.e., triadic connectedness) and adopting culturally inclusive definitions (labeled joint engagement [JE]). Our JE definitions allow for attention and engagement to be expressed in visual and tactile modalities (e.g., for infants experiencing distal or proximal caregiving), with various social partners (e.g., peers, older siblings, mothers), with a range of shared topics (e.g., representing diverse socialization goals, and socio-ecologies with and without toys), and with a range of emotional tone (e.g., for infants living in cultures valuing calmness and low arousal, and those valuing exuberance). Our definition of JE includes initiations from either partner (to include priorities for adult-led or child-led interactions). Our next foundational step is making an ecological commitment to naturalistic observations (Dahl, 2017, Child Dev Perspect, 11(2), 79-84): We measure JE while infants interact within their own physical and social ecologies. This commitment allows us to describe JE as it occurs in everyday contexts, without constraints imposed by researchers. Next, we sample multiple groups of infants drawn from diverse socio-ecological settings. Moreover, we include diverse samples of chimpanzee infants to compare with diverse samples of human infants, to investigate the extent to which JE is unique to humans, and to document diversity both within and between species. We sampled human infants living in three diverse settings. U.K. infants (n = 8) were from western, middle-class families living near universities in the south of England. Nso infants (n = 12) were from communities of subsistence farmers in Cameroon, Africa. Aka infants (n = 10) were from foraging communities in the tropical rain forests of Central African Republic, Africa. We coded behavioral details of JE from videotaped observations (taken between 2004 and 2010). JE occurred in the majority of coded intervals (Mdn = 68%), supporting a conclusion that JE is normative for human infants. The JA phenotype, in contrast, was infrequent, and significantly more common in the U.K. (Mdn = 10%) than the other groups (Mdn < 3%). We found significant within-species diversity in JE phenotypes (i.e., configurations of predominant forms of JE characteristics). We conclude that triadic connectedness is very common in human infants, but there is significant contextualization of behavioral forms of JE. We also studied chimpanzee infants living in diverse socio-ecologies. The PRI/Zoo chimpanzee infants (n = 7) were from captive, stable groups of mixed ages and sexes, and included 4 infants from the Chester Zoo, U.K. and 3 from the Primate Research Institute, Kyoto University, Japan. The Gombe chimpanzee infants (n = 12) were living in a dynamically changing, wild community in the Gombe National Park, Tanzania, Africa. Additionally, we include two Home chimpanzee infants who were reared from birth by a female scientist, in the combined U.S., middle-class contexts of home and university cognition laboratory. JE was coded from videotaped observations (taken between 1993 and 2006). JE occurred during the majority of coded intervals (Mdn = 64%), consistent with the position that JE is normative for chimpanzee infants. The JA phenotype, in contrast, was rare, but more commonly observed in the two Home chimpanzee infants (in 8% and 2% of intervals) than in other chimpanzee groups (Mdns = 0%). We found within-species diversity in the configurations comprising the JE phenotypes. We conclude that triadic connectedness is very common in chimpanzee infants, but behavioral forms of joint engagement are contextualized. We compared JE across species, and found no species-uniqueness in behavioral forms, JE characteristics, or JE phenotypes. Both human and chimpanzee infants develop contextualized social cognition. Within-species diversity is embraced when triadic connectedness is described with culturally inclusive definitions. In contrast, restricting definitions to the JA phenotype privileges a behavioral form most valued in western, middle-class socio-ecologies, irrespective of whether the interactions involve human or chimpanzee infants. Our study presents a model for how to decolonize an important topic in developmental psychology. Decolonization is accomplished by defining the phenomenon inclusively, embracing diversity in sampling, challenging claims of human-uniqueness, and having an ecological commitment to observe infant social cognition as it occurs within everyday socio-ecological contexts. It is essential that evolutionary and developmental theories of social cognition are re-built on more inclusive and decolonized empirical foundations.

Two wild female bonobos adopted infants from a different social group at Wamba

Adoption, the act of taking another individual's offspring and treating it as one's own, is rare but widely observed in various mammal species and may increase the survival of adoptees. Adoption may also benefit adoptive mothers, for example they might care for close kin to gain indirect fitness or to learn caregiving behaviours. Here, we report two cases of a wild bonobo adopting an infant from a different social group, the first report of cross-group adoption in great apes. In one case, the adoptive mother was already a mother of two dependent offspring. In the other case, the adoptive mother was an old parous female whose own offspring had already emigrated into a different social group. The adoptive mothers provided various maternal care to the adoptees, such as carrying, grooming, nursing, and sharing food. No aggression was observed by group members towards the out-group adoptees. In both cases, adoptees had no maternal kin-relationship with their adoptive mothers. Both adoptive mothers already had experience of rearing their own offspring. Instead, these cases of adoption may have been driven by other evolutionary adaptive traits of bonobos, such as their strong attraction to infants and high tolerance towards immatures and out-group individuals.

Learning to Be an Orangutan-Implications of Life History for Orangutan Rehabilitation

Simple Summary

Like humans, great apes have extended childhoods during which they depend on maternal pedagogy. To help rescued orphans recover from maternal loss our rehabilitation programme is modelled on the natural infant development of orangutans. Orphaned apes cannot be released back into freedom before they have learned the skills necessary to survive alone. To prevent suffering after release we documented the development of survival skills during the rehabilitation process. Seven orangutan orphans aged 1.5–9 years were observed over 18 months in their forest school, immersed in a natural forest environment with human surrogate mothers and other orphans. Social interactions deviated from wild mother-reared immatures: Infant orphans spent more time playing with peers, rested less, and were far from their human surrogate mothers earlier and often than wild immatures are from their biological mothers. Around weaning age, 4- to 7-year-old orphans took up a typical orangutan life-style: they interacted less with human surrogate mothers and peers, stayed high in the trees and slept in nests in the forest. Their time budgets resembled those of wild adults. We conclude that it is not only ethical but also possible to assess survival competences of rehabilitant orphans before release and choose release candidates accordingly.

Abstract

Orangutans depend on social learning for the acquisition of survival skills. The development of skills is not usually assessed in rescued orphans’ pre-release. We collected data of seven orphans over an 18-months-period to monitor the progress of ontogenetic changes. The orphans, 1.5–9 years old, were immersed in a natural forest environment with human surrogate mothers and other orphans. Social interactions deviated significantly from those of wild mother-reared immatures. Infants spent more time playing socially with peers, at the expense of resting and solitary play. Infants were also more often and at an earlier age distant from their human surrogate mothers than wild immatures are from their biological mothers. We found important changes towards an orangutan-typical lifestyle in 4- to 7-year-old orphans, corresponding to the weaning age in maternally reared immatures. The older orphans spent less time interacting with human surrogate mothers or peers, started to use the canopy more than lower forest strata and began to sleep in nests in the forest. Their time budgets resembled those of wild adults. In conclusion, juvenile orphans can develop capacities that qualify them as candidates for release back into natural habitat when protected from humanising influences and immersed in a species-typical environment.

Perinatal risk factors and reactive attachment disorder: A nationwide population-based study

AIM

To examine the association between several perinatal and obstetric risk factors and reactive attachment disorder in children diagnosed in specialised services.

METHODS

In this nested case-control study, 614 cases with reactive attachment disorder and 2423 controls matched with age and sex were identified from Finnish national registers. Conditional logistic regression was used to examine the association between a number of perinatal risk factors and reactive attachment disorder.

RESULTS

In the adjusted analysis, a low birthweight of <2500 g was associated with an increased odds of reactive attachment disorder, with an odds ratio (OR) of 1.96 and 95% confidence interval (CI) of 1.17, 3.30 and a birthweight of 4000-4499 grams was associated with decreased odds OR 0.49 (95% CI 0.31, 0.75). The odds for being diagnosed with reactive attachment disorder increased with a gestational age of <32 weeks OR 3.72 (95% CI 1.52, 9.10), induced labour OR 1.34 (95% CI 1.03, 1.75) and monitoring in a neonatal intensive care unit (NICU) OR 1.67 (95% CI 1.09, 2.55).

CONCLUSION

We found associations between low birthweight, preterm birth, NICU admission and reactive attachment disorder. The findings add to the current literature on the understanding of the development of reactive attachment disorder in children.

Bringing up baby: Maternal responsiveness, secondary attachments, and the development of infant social competence in wild olive baboons (Papio anubis)

Caregiver responsiveness and presence of secondary attachments play a crucial role in children's socio-cognitive and emotional development, but little is known of their effect on the development of non-human primates. Here we present the results of a 16-month behavioral study conducted on 22 wild infant olive baboons (Papio anubis) at the Uaso Ngiro Baboon Project, Kenya. This is the first study to examine the effects of maternal responsiveness and secondary attachments on the development of infant social behavior in a wild primate species that does not breed cooperatively. The data track maternal responsiveness and the rates of two behavioral indicators of infant social competence-orienting toward interactions and social play-over the course of the first year of life. Maternal responsiveness decreased as infants grew older, while infant orientation toward interactions and play behavior increased. Infants with poorly responsive mothers were more likely to have secondary attachments, and infants with secondary attachments to siblings oriented more frequently to social interactions than those with secondary attachments to adult/subadult males or with no secondary attachments. These findings indicate that variation in maternal responsiveness and presence of secondary attachments can influence the development of social competence in olive baboon infants.

Early-life adversity and neurological disease: age-old questions and novel answers

Neurological illnesses, including cognitive impairment, memory decline and dementia, affect over 50 million people worldwide, imposing a substantial burden on individuals and society. These disorders arise from a combination of genetic, environmental and experiential factors, with the latter two factors having the greatest impact during sensitive periods in development. In this Review, we focus on the contribution of adverse early-life experiences to aberrant brain maturation, which might underlie vulnerability to cognitive brain disorders. Specifically, we draw on recent robust discoveries from diverse disciplines, encompassing human studies and experimental models. These discoveries suggest that early-life adversity, especially in the perinatal period, influences the maturation of brain circuits involved in cognition. Importantly, new findings suggest that fragmented and unpredictable environmental and parental signals comprise a novel potent type of adversity, which contributes to subsequent vulnerabilities to cognitive illnesses via mechanisms involving disordered maturation of brain 'wiring'.

Heterochrony in chimpanzee and bonobo spatial memory development

OBJECTIVES

The emergence of human-unique cognitive abilities has been linked to our species' extended juvenile period. Comparisons of cognitive development across species can provide new insights into the evolutionary mechanisms shaping cognition. This study examined the development of different components of spatial memory, cognitive mechanisms that support complex foraging, by comparing two species with similar life history that vary in wild ecology: bonobos (Pan paniscus) and chimpanzees (Pan troglodytes).

MATERIALS AND METHODS

Spatial memory development was assessed using a cross-sectional experimental design comparing apes ranging from infancy to adulthood. Study 1 tested 73 sanctuary-living apes on a task examining recall of a single location after a 1-week delay, compared to an earlier session. Study 2 tested their ability to recall multiple locations within a complex environment. Study 3 examined a subset of individuals from Study 2 on a motivational control task.

RESULTS

In Study 1, younger bonobos and chimpanzees of all ages exhibited improved performance in the test session compared to their initial learning experience. Older bonobos, in contrast, did not exhibit a memory boost in performance after the delay. In Study 2, older chimpanzees exhibited an improved ability to recall multiple locations, whereas bonobos did not exhibit any age-related differences. In Study 3, both species were similarly motivated to search for food in the absence of memory demands.

DISCUSSION

These results indicate that closely related species with similar life history characteristics can exhibit divergent patterns of cognitive development, and suggests a role of socioecological niche in shaping patterns of cognition in Pan.

Bushmeat trade consequences predict higher anxiety, restraint, and dominance in chimpanzees

More data are needed for a better understanding of the long-term influence of wider and combined stressful events in chimpanzee personality development. We evaluated the effects of bushmeat trade outcomes on the personality development in 84 African sanctuary chimpanzees. The chimpanzees presented different backgrounds regarding maternal care, social exposure, and abuse. We evaluated personality traits in chimpanzees using the Cattell 16PF personality questionnaire, the first application of this questionnaire in this species. We found that chimpanzees were rated as higher in anxiety after long social deprivation during infancy and juvenility, and if high human exposure was experienced. Mother-reared chimpanzees were rated as lower in restraint than hand-reared chimpanzees. Finally, mother-reared chimpanzees were rated as less dominant than hand-reared chimpanzees and rated higher when they had experienced severe mistreatment. Results suggest a wide range of possible stressful events could be potentially shaping rescued chimpanzees' personality and demonstrating the detrimental outcomes and consequences of the bushmeat and pet trade.

Attachment security in companion dogs: adaptation of Ainsworth's strange situation and classification procedures to dogs and their human caregivers

This exploratory study describes the development of a classification system for dogs’ attachment security to caregivers that adheres closely to Ainsworth’s seminal methodology. Fifty-nine adult dogs and caregivers participated in a mildly threatening laboratory encounter with a stranger (TS) and the Strange Situation (SSP). Dog and attachment experts adapted Ainsworth’s classification system  for the behavioral repertoire of the dog. Four potentially comparable patterns of attachment were identified. The proportions of secure and insecure classifications (61% and 39%) were similar to those found in human toddlers. Caregivers’ sensitivity to their dogs during the TS procedure significantly differentiated dogs with secure vs. insecure classifications Lower scores on the Active/excited personality scale on the Monash Canine Personality Questionnaire-Revised (MCPQ-R) also were related to secure classification. This system now makes it possible to compare directly the effects of human and dog attachment patterns on the health and emotional well-being of humans and dogs.

Early Socioemotional Intervention Mediates Long-Term Effects of Atypical Rearing on Structural Covariation in Gray Matter in Adult Chimpanzees

Atypical rearing has deleterious effects on chimpanzee behavior during development, some of which can be ameliorated with a responsive care intervention (RCI). Here, we obtained in vivo magnetic resonance images of adult brains of 27 chimpanzees given institutional care, with and without RCI, and compared them with those of 16 chimpanzees mother-reared from birth. We found significant long-term rearing effects on structural covariation and gray matter volume, specifically in the basal forebrain (i.e., caudate, putamen, nucleus accumbens, rectus gyrus, and orbital prefrontal cortex), indicating that RCI prevented brain changes due to atypical rearing. A significant correlation between covariation in these brain areas and caregiver nurturing, experienced in the first month of life, suggests a possible developmental mechanism for the effect of early experience on brain networks. We identified an early intervention that prevents changes in the basal forebrain that otherwise emerge as a consequence of institutionalized rearing without species-typical socioemotional experiences.

Play and optimal welfare: Does play indicate the presence of positive affective states?

Play is commonly used to assess affective states in both humans and non-human animals. Play appears to be most common when animals are well-fed and not under any direct threats to fitness. Could play and playfulness therefore indicate pre-existing positive emotions, and thence optimal animal welfare? We examine this question by surveying the internal and external conditions that promote or suppress play in a variety of species, starting with humans. We find that negative affective states and poor welfare usually do suppress play (although there are notable exceptions where the opposite occurs). Furthermore, research in children suggests that beyond the frequency or total duration of play, poor welfare may additionally be reflected in qualitative aspects of this heterogeneous behaviour (e.g. display of solitary over social play; and the 'fragmentation' of play bouts) that are often overlooked in animals. There are surprisingly few studies of play in subjects with pre-existing optimal welfare or in unambiguously highly positive affective states, making it currently impossible to determine whether play can distinguish optimal or good welfare from merely neutral welfare. This therefore represents an important and exciting area for future research.

Mother-infant interactions in captive and wild chimpanzees

We review studies on mother-infant interactions in chimpanzees, our closest living relatives, in captive and wild environments. Infant cognitive development is formed through mother-infant interactions during the long dependent period, which is approximately 5 years. Patterns of interaction between mothers and infants are different from those observed in adult chimpanzees. Mother-infant interactions are relatively altruistic, although solicitation by infants is almost always required. Active teaching has rarely been reported in chimpanzees; instead, infants socially learn new skills through long-term observation. Case studies describing rearing of a disabled infant by a multiparous but inexperienced chimpanzee, and the carrying of dead infants in the wild chimpanzees of Bossou reveal the strong affectionate bond between mothers and infants. Characteristics of human mother-infant interaction are highlighted through comparisons with chimpanzees.

Early maternal loss affects social integration of chimpanzees throughout their lifetime

The long-term effects of early adverse experiences on later psychosocial functioning are well described in humans, but sparsely documented for chimpanzees. In our earlier studies, we investigated the effects of maternal and social deprivation on three groups of ex-laboratory chimpanzees who experienced either an early or later onset of long-term deprivation. Here we expand our research by adding data on subjects that came from two stable zoo groups. The groups comprised of early maternally deprived wild-caught chimpanzees and non-deprived zoo-born chimpanzees. We found that compared to zoo chimpanzees, ex-laboratory chimpanzees were more restricted regarding their association partners in the newly formed groups, but not during their second year of group-life, indicating that social stability has an important influence on the toleration of association partners close-by. Social grooming activity, however, was impaired in early long-term deprived ex-laboratory chimpanzees as well as in early maternally deprived zoo chimpanzees compared to non-deprived zoo chimpanzees. Thus, we conclude that early maternal loss has lifelong effects on the social integration of chimpanzees which becomes evident in their grooming networks. Although the retrospective nature of our study prevents a clear causal explanation, our results are of importance for understanding the development of social competence in chimpanzees.

Domestic Cats (Felis silvestris catus) Do Not Show Signs of Secure Attachment to Their Owners

The Ainsworth Strange Situation Test (SST) has been widely used to demonstrate that the bond between both children and dogs to their primary carer typically meets the requirements of a secure attachment (i.e. the carer being perceived as a focus of safety and security in otherwise threatening environments), and has been adapted for cats with a similar claim made. However methodological problems in this latter research make the claim that the cat-owner bond is typically a secure attachment, operationally definable by its behaviour in the SST, questionable. We therefore developed an adapted version of the SST with the necessary methodological controls which include a full counterbalance of the procedure. A cross-over design experiment with 20 cat-owner pairs (10 each undertaking one of the two versions of the SST first) and continuous focal sampling was used to record the duration of a range of behavioural states expressed by the cats that might be useful for assessing secure attachment. Since data were not normally distributed, non-parametric analyses were used on those behaviours shown to be reliable across the two versions of the test (which excluded much cat behaviour). Although cats vocalised more when the owner rather the stranger left the cat with the other individual, there was no other evidence consistent with the interpretation of the bond between a cat and its owner meeting the requirements of a secure attachment. These results are consistent with the view that adult cats are typically quite autonomous, even in their social relationships, and not necessarily dependent on others to provide a sense of security and safety. It is concluded that alternative methods need to be developed to characterise the normal psychological features of the cat-owner bond.

Primate sociality to human cooperation. Why us and not them?

Developmental psychologists identify propensities for social engagement in human infants that are less evident in other apes; Sarah Hrdy links these social propensities to novel features of human childrearing. Unlike other ape mothers, humans can bear a new baby before the previous child is independent because they have help. This help alters maternal trade-offs and so imposes new selection pressures on infants and young children to actively engage their caretakers' attention and commitment. Such distinctive childrearing is part of our grandmothering life history. While consequences for other cooperative activities must surely follow, the novel rearing environments set up by helpful grandmothering can explain why natural selection escalated preferences and motivations for interactivity in our lineage in the first place, and why, unlike other aspects of infant development, social sensitivities are not delayed in humans compared with genus Pan.

The Importance of Development for Comparative Primatology

It is a truism to say that primates develop, but it is also important to acknowledge that development occurs across many domains, including motor behavior, socioemotional behavior, communication, and cognition. In this review, we focus on those aspects of development that impact social cognition outcomes in infancy. Triadic engagements, such as those of joint attention, cooperation, and intentional communication, develop in the first year of life in chimpanzees and humans. Joint attention, for example, occurs when infants coordinate their attention to a social partner while also attending to an object or event. Hominoids are strongly influenced by experiences during early development, especially experiences that are foundational for these coordinated triadic engagements. Purported species differences in triadic engagements are highlighted in current evolutionary theories of primate social cognition, but conclusions about species differences are unfounded when development is ignored. Developmental experiences must be matched, controlled, or systematically varied in experimental designs that make cross-species comparisons. Considerations of development, across species and across rearing experiences, would contribute to more accurate evolutionary theories of primate social cognition.

The impact of atypical early histories on pet or performer chimpanzees

It is widely accepted that an animal's early history, including but not limited to its rearing history, can have a profound impact on later behavior. In the case of captive animals, many studies have used categorical measures such as mother reared or human reared that do not account for both the influence of human and conspecific interaction. In order to account for the influence of both human and conspecific early exposure to later behavior, we collected 1385 h of data on 60 chimpanzees, of which 36 were former pets or performers, currently housed at accredited zoos or sanctuaries. We developed a unique metric, the Chimpanzee-Human Interaction (CHI) Index that represented a continuous measure of the proportion of human and chimpanzee exposure subjects experienced and here focused on their exposure during the first four years of life. We found that chimpanzees who experienced less exposure to other chimpanzees as infants showed a lower frequency of grooming and sexual behaviors later in life which can influence social dynamics within groups. We also found chimpanzees who experienced more exposure to other chimpanzees as infants showed a higher frequency of coprophagy, suggesting coprophagy could be a socially-learned behavior. These results help characterize some of the long-term effects borne by chimpanzees maintained as pets and performers and may help inform managers seeking to integrate these types of chimpanzees into larger social groups, as in zoos and sanctuaries. In addition, these results highlight the necessity of taking into account the time-weighted influence of human and conspecific interactions when assessing the impact that humans can have on animals living in captivity.

Imitation promotes affiliation in infant macaques at risk for impaired social behaviors

Parental responsiveness and synchronization during early face-to-face interactions between mother and infant have been theorized to affect a broad spectrum of positive developmental outcomes in social and cognitive infant growth and to facilitate the development of a sense of self in the baby. Here we show that being imitated can significantly affect the behavior of nursery-reared infant monkeys, which are at an increased risk for developing aberrant social behaviors. Infants look longer and lipsmack more at an experimenter both during imitation and after being imitated. These results demonstrate that from early in life imitation might be used as a privileged form of communication by adults to enhance infants' visual engagement and their social communication. Imitation may therefore be useful to counteract the negative effects of early social adversities.

Emotional engagements predict and enhance social cognition in young chimpanzees

Social cognition in infancy is evident in coordinated triadic engagements, that is, infants attending jointly with social partners and objects. Current evolutionary theories of primate social cognition tend to highlight species differences in cognition based on human-unique cooperative motives. We consider a developmental model in which engagement experiences produce differential outcomes. We conducted a 10-year-long study in which two groups of laboratory-raised chimpanzee infants were given quantifiably different engagement experiences. Joint attention, cooperativeness, affect, and different levels of cognition were measured in 5- to 12-month-old chimpanzees, and compared to outcomes derived from a normative human database. We found that joint attention skills significantly improved across development for all infants, but by 12 months, the humans significantly surpassed the chimpanzees. We found that cooperativeness was stable in the humans, but by 12 months, the chimpanzee group given enriched engagement experiences significantly surpassed the humans. Past engagement experiences and concurrent affect were significant unique predictors of both joint attention and cooperativeness in 5- to 12-month-old chimpanzees. When engagement experiences and concurrent affect were statistically controlled, joint attention and cooperation were not associated. We explain differential social cognition outcomes in terms of the significant influences of previous engagement experiences and affect, in addition to cognition. Our study highlights developmental processes that underpin the emergence of social cognition in support of evolutionary continuity.

Arousal regulation and affective adaptation to human responsiveness by a robot that explores and learns a novel environment

In the context of our work in developmental robotics regarding robot-human caregiver interactions, in this paper we investigate how a "baby" robot that explores and learns novel environments can adapt its affective regulatory behavior of soliciting help from a "caregiver" to the preferences shown by the caregiver in terms of varying responsiveness. We build on two strands of previous work that assessed independently (a) the differences between two "idealized" robot profiles-a "needy" and an "independent" robot-in terms of their use of a caregiver as a means to regulate the "stress" (arousal) produced by the exploration and learning of a novel environment, and (b) the effects on the robot behaviors of two caregiving profiles varying in their responsiveness-"responsive" and "non-responsive"-to the regulatory requests of the robot. Going beyond previous work, in this paper we (a) assess the effects that the varying regulatory behavior of the two robot profiles has on the exploratory and learning patterns of the robots; (b) bring together the two strands previously investigated in isolation and take a step further by endowing the robot with the capability to adapt its regulatory behavior along the "needy" and "independent" axis as a function of the varying responsiveness of the caregiver; and (c) analyze the effects that the varying regulatory behavior has on the exploratory and learning patterns of the adaptive robot.

Development of socio-emotional competence in bonobos

Social and emotional skills are tightly interlinked in human development, and both are negatively impacted by disrupted social development. The same interplay between social and emotional skills, including expressions of empathy, has received scant attention in other primates however, despite the growing interest in caring, friendships, and the fitness benefits of social skills. Here we examine the development of socio-emotional competence in juvenile bonobos (Pan paniscus) at a sanctuary in the Democratic Republic of the Congo, focusing on the interplay between various skills, including empathy-related responding. Most subjects were rehabilitated orphans, but some were born at the sanctuary and mother-reared there. We observed how juveniles with different rearing backgrounds responded to stressful events, both when the stress affected themselves (e.g., a lost fight) or others (e.g., witnessing the distress of others). The main dependent variable was the consolation of distressed parties by means of calming body contact. As in children, consolation was predicted by overall social competence and effective emotion regulation, as reflected in the speed of recovery from self-distress and behavioral measures of anxiety. Juveniles more effective at self-regulation were more likely to console others in distress, and such behavior was more typical of mother-reared juveniles than orphans. These results highlight the interplay between the development of social and emotional skills in our ape relatives and the importance of the mother-offspring bond in shaping socio-emotional competence.

Does the attachment system towards owners change in aged dogs?

Changes during senescence can significantly affect both the emotional and relational needs of old individuals and the characteristics of the attachment system. In order to determine whether the emotional response of dogs is affected by old age, we compared the behavioural parameters of adult (AD <7 years of age, n=25) and aged (AG ≥7 years of age, n=25) dogs in a distressing situation, which gives rise to attachment behaviour patterns (Strange Situation Test, SST). The physiological response of dogs was assessed by measurement of salivary cortisol variations in samples collected both at the dogs' homes and at the study location, before and after the SST. Both groups of dogs expressed clear-cut patterns of attachment to their owners. During the initial part of the procedure, AG dogs sought more physical contact, but behaved more passively and showed less interest in an unknown person during separation from their owners. Compared with AD dogs, AG ones showed a significant increase in salivary cortisol concentrations after the SST. The combination of physiological and behavioural data of the present study supports the hypothesis that, later in life, dogs cope less efficiently with emotional distress caused by mild social challenge.

Bonobos respond to distress in others: consolation across the age spectrum

How animals respond to conflict provides key insights into the evolution of socio-cognitive and emotional capacities. Evidence from apes has shown that, after social conflicts, bystanders approach victims of aggression to offer stress-alleviating contact behavior, a phenomenon known as consolation. This other-orientated behavior depends on sensitivity to the other's emotional state, whereby the consoler acts to ameliorate the other's situation. We examined post-conflict interactions in bonobos (Pan paniscus) to identify the determinants of consolation and reconciliation. Thirty-six semi-free bonobos of all ages were observed at the Lola ya Bonobo Sanctuary, DR Congo, using standardized Post-conflict/Matched Control methods. Across age and sex classes, bonobos consoled victims and reconciled after conflicts using a suite of affiliative and socio-sexual behaviors including embracing, touching, and mounting. Juveniles were more likely to console than adults, challenging the assumption that comfort-giving rests on advanced cognitive mechanisms that emerge only with age. Mother-reared individuals were more likely to console than orphans, highlighting the role of rearing in emotional development. Consistent with previous studies, bystanders were more likely to console relatives or closely bonded partners. Effects of kinship, affiliation and rearing were similarly indicated in patterns of reconciliation. Nearby bystanders were significantly more likely to contact victims than more distal ones, and consolation was more likely in non-food contexts than during feeding. The results did not provide convincing evidence that bystander contacts served for self-protection or as substitutes for reconciliation. Overall, results indicate that a suite of social, developmental and contextual factors underlie consolation and reconciliation in bonobos and that a sensitivity to the emotions of others and the ability to provide appropriate consolatory behaviors emerges early in development.

Vocal signature in wild infant chimpanzees

A large array of communication signals supports the fission/fusion social organization in chimpanzees, and among them the acoustic channel plays a large part because of their forest habitat. Adult vocalizations convey social and ecological information to their recipients allowing them to obtain cues about an ongoing event from calls only. In contrast to adult vocalizations, information encoded in infant calls had been hardly investigated. Studies mainly focused on vocal development. The present article aims at assessing the acoustic cues that support individual identity coding in infant chimpanzees. By analyzing recordings performed in the wild from seven 3-year-old infant chimpanzees, we showed that their calls support a well-defined individual vocal signature relying on spectral cues. To assess the reliability of the signature across the calls of an individual, we defined two subsets of recordings on the basis of the characteristics of the frequency modulation (whimpers and screams) and showed that both call types present a reliable vocal signature. Early vocal signature may allow the mother and other individuals in the group to identify the infant caller when visual contact is broken. Chimpanzee mothers may have developed abilities to cope with changing vocal signatures while their infant, still vulnerable, gains in independence in close habitat.

Anxiety-related behavior of orphan chimpanzees (Pan troglodytes schweinfurthii) at Gombe National Park, Tanzania

This study examined the anxiety levels and social interactions of two orphan and four mother-reared adolescent chimpanzees (Pan troglodytes schweinfurthii) in the Kasekela community at Gombe National Park, Tanzania. We used focal sampling in the field at Gombe to observe these adolescent individuals. Their social interactions and anxious behavior, measured as rough scratching, were recorded. The two orphans differed from others of a similar age by exhibiting higher levels of anxiety and lower levels of play. These results suggest that a mother's absence, even in naturalistic conditions in which other members of the community are available to the orphan, may have long-lasting impact on an adolescent's anxiety and its ability to engage in complex social interactions, such as play.

Psychological health of orphan bonobos and chimpanzees in African sanctuaries

BACKGROUND

Facilities across Africa care for apes orphaned by the trade for "bushmeat." These facilities, called sanctuaries, provide housing for apes such as bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) who have been illegally taken from the wild and sold as pets. Although these circumstances are undoubtedly stressful for the apes, most individuals arrive at the sanctuaries as infants and are subsequently provided with rich physical and social environments that can facilitate the expression of species-typical behaviors.

METHODS AND FINDINGS

We tested whether bonobo and chimpanzee orphans living in sanctuaries show any behavioral, physiological, or cognitive abnormalities relative to other individuals in captivity as a result of the early-life stress they experience. Orphans showed lower levels of aberrant behaviors, similar levels of average cortisol, and highly similar performances on a broad battery of cognitive tests in comparisons with individuals of the same species who were either living at a zoo or were reared by their mothers at the sanctuaries.

CONCLUSION

Taken together, these results support the rehabilitation strategy used by sanctuaries in the Pan-African Sanctuary Alliance (PASA) and suggest that the orphans we examined did not show long-term signs of stress as a result of their capture. Our findings also show that sanctuary apes are as psychologically healthy as apes in other captive settings and thus represent a valuable resource for non-invasive research.

Environmental Influences on Joint Attention in Great Apes: Implications for Human Cognition

In humans, cultural differences in advanced social cognition have been well demonstrated. In tasks pertaining to theory of mind, for instance, individuals pass standard assessments of false-belief understanding at substantially different ages in different cultural environments. Less well-studied are more basic sociocognitive capacities, such as joint attention, which are held by many to constitute the foundational skill set for advanced sociocognitive reasoning. Here, we review the striking group differences in joint attention displayed by great apes as a consequence of being raised in different cultural environments, including wild habitats, institutional settings such as zoos and biomedical research centers, and home-rearing or language-training settings. Like humans, apes develop tactics for joint attention that are adaptive to the particular environments of their early rearing experiences. Great apes serve as animal models for environmental influences on sociocognitive capacities in our own species.

Neurobehavioral Integrity of Chimpanzee Newborns: Comparisons across groups and across species reveal gene-environment interaction effects

The aims of this article are to describe the neurobehavioral integrity of chimpanzee newborns, to investigate how early experiences affect the neurobehavioral organization of chimpanzees, and to explore species differences by comparing chimpanzee newborns to a group of typically developing human newborns. Neurobehavioral integrity related to orientation, motor performance, arousal, and state regulation of 55 chimpanzee (raised in four different settings) and 42 human newborns was measured with the Neonatal Behavioral Assessment Scale (NBAS) a semi-structured 25-minute interactive assessment. Thirty-eight chimpanzees were tested every other day from birth, and analyses revealed significant developmental changes in 19 of 27 NBAS scores. The cross-group and cross-species comparisons were conducted at 2 and 30 days of age. Among the 4 chimpanzee groups, significant differences were found in 23 of 24 NBAS scores. Surprisingly, the cross-species comparisons revealed that the human group was distinct in only 1 of 25 NBAS scores (the human group had significantly less muscle tone than all the chimpanzee groups). The human group was indistinguishable from at least one of the chimpanzee groups in the remaining 24 of 25 NBAS scores. The results of this study support the conclusion that the interplay between genes and environment, rather than genes alone or environment alone, accounts for phenotypic expressions of newborn neurobehavioral integrity in hominids.

Children with disrupted attachment histories: interventions and psychophysiological indices of effects

Diagnosis and treatment of children affected by disruptions of attachment (out of home placement, multiple changes of primary caregiver) is an area of considerable controversy. The possible contribution of psychobiological theories is discussed in three parts. The first part relates the attachment theoretical perspective to major psychobiological theories on the developmental associations of parent-child relationships and emotional response. The second part reviews studies of autonomic reactivity and HPA-axis activity with foster children, showing that foster children show more reactivity within physiological systems facilitating fight or flight behaviours rather than social engagement, especially foster children with atypical attachment behaviour. The third part is focused on treatment of children suffering from the consequences of disrupted attachment, based on a psychotherapy study with psychophysiological outcome measures. Implications are discussed for theory, diagnosis, and intervention.