In common marmosets, the brain regions that process social interactions develop very slowly, extending until early adulthood, like in humans. During this time, all group members are involved in raising the infants, which contributes to the species’ strong socio-cognitive skills.
The development of primate brains is shaped by various inputs. However, these inputs differ between independent breeders, such as great apes, and cooperative breeders, such as the common marmoset (Callithrix jacchus) and humans. In these species, group members other than the parents contribute substantially to raising the infants from birth onwards.
A group of international researchers led by Paola Cerrito from the University of Zurich’s Department of Evolutionary Anthropology studied how such social interactions map onto brain development in common marmosets. The study provides new insights into the relationship between the timing of brain development and the socio-cognitive skills of marmosets, in particular their prosocial and cooperative behaviors.
Prolonged learning from social interactions
The research team analyzed brain development using magnetic resonance data and showed that in marmosets, the brain regions involved in the processing of social interactions exhibit protracted development — in a similar way to humans. These brain regions only reach maturity in early adulthood, allowing the animals to learn from social interactions for longer.
Like humans, immature marmosets are surrounded and cared for by multiple caregivers from birth and are therefore exposed to intense social interaction. Feeding is also a cooperative business: the immature animals are fed by group members and as they get older, they have to beg for food because their mothers are already busy with the next offspring. According to the study, the need to elicit care from several group members significantly shapes brain development and contributes to the sophisticated socio-cognitive motivation (and observed skills) of these primates.
A model for human evolution
Given their similarities with humans, marmosets are an important model for studying the evolution of social cognition. “Our findings underscore the importance of social experiences to the formation of neural and cognitive networks, not only in primates, but also in humans,” explains Cerrito.
The early-life social inputs that characterize infants’ life in cooperatively breeding species may be a driving force in the development of humans’ marked social motivation. “This insight could have an impact on various fields, ranging from evolutionary biology to neuroscience and psychology,” adds Cerrito.