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Early social deprivation in highly social mammals interferes with their varying needs for security and stimulation. Toleration of social stimulation was studied in 18 adult ex-laboratory chimpanzees, who had been deprived for 16 to 27 years, during their 1st year after resocialization into 1 of 3 social groups. For this, a model of social competence was developed with 5 grades of social stimulation. The chimpanzees were classified as either early deprived (EDs; M = 1.2 years) or late deprived (LDs; M = 3.6 years) according to their age at entering the laboratory. EDs did not differ significantly from LD chimpanzees in the first 3 grades of social stimulation (i.e., the toleration of stationary vicinity, initiation of brief sociopositive contacts and gentle social play). LDs, however, clearly exceeded EDs in the 4th and 5th grade of social stimulation (i.e., their engagement in allogrooming and their toleration of passive close proximity). Furthermore, LDs showed greater social initiative in changing a social Situation and had more expanded grooming networks compared with EDs. Moreover, in LDs and ED females, but not in ED males, toleration of stationary vicinity increased from the 1st to the 2nd year of group living. [ABSTRACT FROM AUTHOR]

Simple Summary: Experiences during infancy and as a juvenile are very influential on the lives of primates into adulthood. In this sense, the living conditions of chimpanzees kept as pets or performing in circuses cannot fulfil the three basic requirements needed for these animals to develop properly: adequate functioning of the organism (physical well-being); an optimal emotional state with the absence of sensations such as fear, pain, grief or apathy (mental well-being); and the ability to express species-specific behaviours (social well-being). In this study, we compare the activity budgets of three chimpanzees approximately one-decade post-rescue, to historical activity data before their rehabilitation. We found changes in behavior patterns in accordance with the sanctuary rehabilitation objectives. All chimpanzees improved their social competence by adding new members to their social network. Vigilance behavior also declined, and time spent resting increased when living at the sanctuary. Our results support previous studies conducted with rehabilitated chimpanzees in sanctuaries and highlight the important work of dedicated professionals during the rehabilitation process for these chimpanzees housed in captivity for the rest of their life. Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions from early infancy onwards. The preferred option for ending their existence as pet or circus chimpanzees is their rescue and transfer to a primate sanctuary that will provide them with optimal living and social conditions, so that they can thrive. In this case study, we had the rare opportunity to compare the activity budgets of three chimpanzees from their time as pets in 2004 to their time living at the MONA sanctuary in 2020, after almost a decade in the centre. We found their behaviour patterns changed in accordance with the sanctuaries' rehabilitation objectives. Resting periods increased considerably while vigilance simultaneously declined sharply. Moreover, the chimpanzees' social competence increased as allogrooming became the predominant social behaviour, and agonistic interactions diminished even though they were living within a larger social group at the sanctuary. All three chimpanzees expanded their allogrooming and proximity networks at the sanctuary, which included new group members, but they maintained the closest relationships to those conspecifics who they were rescued with. In conclusion, these findings suggest that the sanctuary environment and social group setting made it possible for these three chimpanzees to improve their social competence and increase their well-being over time. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]