Comparing infant and juvenile behavior in bonobos (Pan paniscus) and chimpanzees (Pan troglodytes): a preliminary study

Abstract

The dichotomy between the two Pan species, the bonobo (Pan paniscus) and chimpanzee (Pan troglodytes) has been strongly emphasized until very recently. Given that most studies were primarily based on adult individuals, we shifted the "continuity versus discontinuity" discussion to the infant and juvenile stage. Our aim was to test quantitatively, some conflicting statements made in literature considering species differences between immature bonobos and chimpanzees. On one hand it is suggested that infant bonobos show retardation in motor and social development when compared with chimpanzees. Additionally it is expected that the weaning process is more traumatic to chimpanzee than bonobo infants. But on the other hand the development of behaviors is expected to be very similar in both species. We observed eight mother-infant pairs of each species in several European zoos. Our preliminary research partially confirms that immature chimpanzees seem spatially more independent, spending more time at a larger distance from their mother than immature bonobos. However, the other data do not seem to support the hypothesis that bonobo infants show retardation of motor or social development. The development of solitary play, environmental exploration, social play, non-copulatory mounts and aggressive interactions do not differ between the species. Bonobo infants in general even groom other group members more than chimpanzee infants. We also found that older bonobo infants have more nipple contact than same aged chimpanzees and that the weaning process seems to end later for bonobos than for immature chimpanzee. Additionally, although immature bonobos show in general more signs of distress, our data suggest that the weaning period itself is more traumatic for chimpanzees.

Nutritional Phases in Prader-Willi Syndrome: Evolutionary and Clinical Interpretations

“…Adrenarche occurs at around the age of weaning in great apes: bonobos wean after four years [22] with increases in adrenal androgens after five years [23]; orangutans wean after seven years [24] with increases in adrenal androgens after eight years [25]. Campbell noted that increased production of adrenal androgens accompanies independence from mothers at weaning in rodents and monkeys but occurs much later than weaning in humans [26].…”

Stable and fluctuating social preferences and implications for cooperation among female bonobos at LuiKotale, Salonga National Park, DRC

“…We used LMMs with Gaussian error structure to determine whether variation in social preference indices (response variables) was influenced by the following dyadic attributes (test predictors): (1) Putative maternal relatedness, based on results of the genetic analyses; (2) Scaled rank distance, calculated as: (Dyadic rank distance AB − Dyadic rank distance min )/(Dyadic rank distance max − Dyadic rank distance min ); (3) Duration of observation time during which both females had offspring less than four years of age, based on evidence that most young are weaned by that age (De Lathouwers & Van Elsacker, ; Oelze, ); and (4) Dyadic co‐residency time at the beginning of the study, categorized as short (1 year), intermediate (4 years) or long (8+ years). To account for potential influences of adult sons on female social behavior (e.g., Surbeck, Mundry, & Hohmann, ), we included whether each female had an adult son (categorical) as a control predictor.…”

Successful behavioural adaptation of an orphaned juvenile Bonobo Pan paniscus: a case study at the Primate Park Apenheul, the Netherlands

“…Hence, there are no clear indications that the solitary play behaviour of the juvenile ♀ was affected by the loss of her mother. The same can be said for the evolution in exploration of the environment and for the initiated social play; these behaviours follow the expected developmental pattern (De Lathouwers & Van Elsacker, 2006) and seem, therefore, not to be affected by the mother's death. It is possible that the play and exploration behaviour of the juvenile may have been affected shortly after her mother's death.…”

“…The juvenile groomed other members of the social group significantly more in the orphan period. Although grooming normally increases with age (De Lathouwers & Van Elsacker, 2006), the orphaned juvenile spent twice as much of her time grooming other group members compared with other Bonobo juveniles of a similar age. Grooming is a highly important social skill.…”

“…Solitary play in immature Bonobo is known to increase until c. 30 months of age. After that time, mainly owing to greater inter-individual variation, the relationship between solitary play and age becomes less clear (De Lathouwers & Van Elsacker, 2006).…”