Many species that are highly social undergo a process, called socialization, in which they acquire different skills (i.e. reproductive behaviors, foraging, etc.) that are beneficial to their fitness within an environment. The attainment of such social skills result in higher fitness, as individuals are required to learn them prior to reaching the age of maturity and independence. As a result, socialization enables the individuals to live efficiently and adequately in group settings, contributing to more of a fitness advantage as they become better adapted to their social environments. With primates, more specifically, parental care and investment play a significant role in an individual’s acquisition of relative skills that are necessary for survival. For this experiment, differences in skill acquisition between mother-reared (presence of maternal figure during childhood) and orphaned juvenile (absence of mother during childhood) chimpanzees were examined. Ultimately, the focus was pertaining to how paternal care during the juvenile period contributed to the development of social skills by these primates later in adulthood.
Chimpanzees from the Chimfunshi Wildlife Orphanage Trust of Zambia were used as the test subjects for this experiment. The orphaned chimpanzees included 8 test subjects (4 females, 4 males), while the mother-reared group consisted of 9 test subjects (5 females, 4 males). In this study, researchers were observing the effects of maternal presence on the success of orphaned and mother-reared chimpanzees to obtain a particular social skill, based on exposure to a type of social interaction. Social play was used as the interaction, considering that, during social play, an individual that possesses social skills associated with social play would be less likely to resort to escalating behavior like aggression (i.e. biting, kicking, throwing objects). It was hypothesized that orphaned juveniles (adults who had no mother as an infant) would be less likely to engage in social play behavior than the mother-rearing juveniles, given that the orphans had less exposure to a maternal figure who would assure them that their social environment with other chimpanzees was safe. The experimenters were able to test this assumption by measuring rates of aggression using behavioral coding. Aggressive and non-aggressive behaviors were measured over time intervals that were less than 5 minutes, as social play interactions were observed within each of the two specific groups (orphan juvenile with orphan juvenile and mother reared with mother reared). The results were that the orphaned individuals participated in social play more often than mother-reared individuals, but during a shorter time period. These data rejected the part of the hypothesis that stated that orphaned juveniles would be less likely to engage in such behaviors. However, the probability that social play would result in aggression was greater for the orphans compared to the mother-reared. In the case of the orphans, this observation supports the idea that parental absence during childhood could have reduced the ability of these individuals to attain the appropriate social skills required for social play.
The findings described in the experiment suggest that early social encounters, especially maternal investment, help to facilitate social development of offspring. As demonstrated, the chimpanzees raised without a mother had an impaired ability to prevent aggressive behaviors during playful interactions. These observations are important in that they imply the significance of parental care in increasing the fitness of animals in highly social environments or group-like settings. Animals that are capable of acquiring skills that are pertinent to their interactions with other animals will become better suited for their surroundings, securing their potential to have a fitness advantage and increasing their chances of survival. The study could be applicable in real-life situations where young chimpanzees or other juvenile primates may be isolated from their families and held in captivity. The consequences of such an intruding act can thereby be similar to those explained by this experiment.
References:
van Leeuwen, E., Mulenga, I., Chidester, D. (2014). Early social deprivation negatively affects social skill acquisition in chimpanzees (Pan troglodytes). Animal Cognition, 17(2), 407-414, doi: 10.1007/s10071-013- 0672-5.
